granicus.if.org Git - imagemagick/blob - magick/quantize.c

   1 /*
   2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   3 %                                                                             %
   4 %                                                                             %
   5 %                                                                             %
   6 %           QQQ   U   U   AAA   N   N  TTTTT  IIIII   ZZZZZ  EEEEE            %
   7 %          Q   Q  U   U  A   A  NN  N    T      I        ZZ  E                %
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  11 %                                                                             %
  12 %                                                                             %
  13 %    MagickCore Methods to Reduce the Number of Unique Colors in an Image     %
  14 %                                                                             %
  15 %                           Software Design                                   %
  16 %                             John Cristy                                     %
  17 %                              July 1992                                      %
  18 %                                                                             %
  19 %                                                                             %
  20 %  Copyright 1999-2011 ImageMagick Studio LLC, a non-profit organization      %
  21 %  dedicated to making software imaging solutions freely available.           %
  22 %                                                                             %
  23 %  You may not use this file except in compliance with the License.  You may  %
  24 %  obtain a copy of the License at                                            %
  25 %                                                                             %
  26 %    http://www.imagemagick.org/script/license.php                            %
  27 %                                                                             %
  28 %  Unless required by applicable law or agreed to in writing, software        %
  29 %  distributed under the License is distributed on an "AS IS" BASIS,          %
  30 %  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
  31 %  See the License for the specific language governing permissions and        %
  32 %  limitations under the License.                                             %
  33 %                                                                             %
  34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  35 %
  36 %  Realism in computer graphics typically requires using 24 bits/pixel to
  37 %  generate an image.  Yet many graphic display devices do not contain the
  38 %  amount of memory necessary to match the spatial and color resolution of
  39 %  the human eye.  The Quantize methods takes a 24 bit image and reduces
  40 %  the number of colors so it can be displayed on raster device with less
  41 %  bits per pixel.  In most instances, the quantized image closely
  42 %  resembles the original reference image.
  43 %
  44 %  A reduction of colors in an image is also desirable for image
  45 %  transmission and real-time animation.
  46 %
  47 %  QuantizeImage() takes a standard RGB or monochrome images and quantizes
  48 %  them down to some fixed number of colors.
  49 %
  50 %  For purposes of color allocation, an image is a set of n pixels, where
  51 %  each pixel is a point in RGB space.  RGB space is a 3-dimensional
  52 %  vector space, and each pixel, Pi,  is defined by an ordered triple of
  53 %  red, green, and blue coordinates, (Ri, Gi, Bi).
  54 %
  55 %  Each primary color component (red, green, or blue) represents an
  56 %  intensity which varies linearly from 0 to a maximum value, Cmax, which
  57 %  corresponds to full saturation of that color.  Color allocation is
  58 %  defined over a domain consisting of the cube in RGB space with opposite
  59 %  vertices at (0,0,0) and (Cmax, Cmax, Cmax).  QUANTIZE requires Cmax =
  60 %  255.
  61 %
  62 %  The algorithm maps this domain onto a tree in which each node
  63 %  represents a cube within that domain.  In the following discussion
  64 %  these cubes are defined by the coordinate of two opposite vertices:
  65 %  The vertex nearest the origin in RGB space and the vertex farthest from
  66 %  the origin.
  67 %
  68 %  The tree's root node represents the entire domain, (0,0,0) through
  69 %  (Cmax,Cmax,Cmax).  Each lower level in the tree is generated by
  70 %  subdividing one node's cube into eight smaller cubes of equal size.
  71 %  This corresponds to bisecting the parent cube with planes passing
  72 %  through the midpoints of each edge.
  73 %
  74 %  The basic algorithm operates in three phases: Classification,
  75 %  Reduction, and Assignment.  Classification builds a color description
  76 %  tree for the image.  Reduction collapses the tree until the number it
  77 %  represents, at most, the number of colors desired in the output image.
  78 %  Assignment defines the output image's color map and sets each pixel's
  79 %  color by restorage_class in the reduced tree.  Our goal is to minimize
  80 %  the numerical discrepancies between the original colors and quantized
  81 %  colors (quantization error).
  82 %
  83 %  Classification begins by initializing a color description tree of
  84 %  sufficient depth to represent each possible input color in a leaf.
  85 %  However, it is impractical to generate a fully-formed color description
  86 %  tree in the storage_class phase for realistic values of Cmax.  If
  87 %  colors components in the input image are quantized to k-bit precision,
  88 %  so that Cmax= 2k-1, the tree would need k levels below the root node to
  89 %  allow representing each possible input color in a leaf.  This becomes
  90 %  prohibitive because the tree's total number of nodes is 1 +
  91 %  sum(i=1, k, 8k).
  92 %
  93 %  A complete tree would require 19,173,961 nodes for k = 8, Cmax = 255.
  94 %  Therefore, to avoid building a fully populated tree, QUANTIZE: (1)
  95 %  Initializes data structures for nodes only as they are needed;  (2)
  96 %  Chooses a maximum depth for the tree as a function of the desired
  97 %  number of colors in the output image (currently log2(colormap size)).
  98 %
  99 %  For each pixel in the input image, storage_class scans downward from
 100 %  the root of the color description tree.  At each level of the tree it
 101 %  identifies the single node which represents a cube in RGB space
 102 %  containing the pixel's color.  It updates the following data for each
 103 %  such node:
 104 %
 105 %    n1: Number of pixels whose color is contained in the RGB cube which
 106 %    this node represents;
 107 %
 108 %    n2: Number of pixels whose color is not represented in a node at
 109 %    lower depth in the tree;  initially,  n2 = 0 for all nodes except
 110 %    leaves of the tree.
 111 %
 112 %    Sr, Sg, Sb: Sums of the red, green, and blue component values for all
 113 %    pixels not classified at a lower depth. The combination of these sums
 114 %    and n2  will ultimately characterize the mean color of a set of
 115 %    pixels represented by this node.
 116 %
 117 %    E: the distance squared in RGB space between each pixel contained
 118 %    within a node and the nodes' center.  This represents the
 119 %    quantization error for a node.
 120 %
 121 %  Reduction repeatedly prunes the tree until the number of nodes with n2
 122 %  > 0 is less than or equal to the maximum number of colors allowed in
 123 %  the output image.  On any given iteration over the tree, it selects
 124 %  those nodes whose E count is minimal for pruning and merges their color
 125 %  statistics upward. It uses a pruning threshold, Ep, to govern node
 126 %  selection as follows:
 127 %
 128 %    Ep = 0
 129 %    while number of nodes with (n2 > 0) > required maximum number of colors
 130 %      prune all nodes such that E <= Ep
 131 %      Set Ep to minimum E in remaining nodes
 132 %
 133 %  This has the effect of minimizing any quantization error when merging
 134 %  two nodes together.
 135 %
 136 %  When a node to be pruned has offspring, the pruning procedure invokes
 137 %  itself recursively in order to prune the tree from the leaves upward.
 138 %  n2,  Sr, Sg,  and  Sb in a node being pruned are always added to the
 139 %  corresponding data in that node's parent.  This retains the pruned
 140 %  node's color characteristics for later averaging.
 141 %
 142 %  For each node, n2 pixels exist for which that node represents the
 143 %  smallest volume in RGB space containing those pixel's colors.  When n2
 144 %  > 0 the node will uniquely define a color in the output image. At the
 145 %  beginning of reduction,  n2 = 0  for all nodes except a the leaves of
 146 %  the tree which represent colors present in the input image.
 147 %
 148 %  The other pixel count, n1, indicates the total number of colors within
 149 %  the cubic volume which the node represents.  This includes n1 - n2
 150 %  pixels whose colors should be defined by nodes at a lower level in the
 151 %  tree.
 152 %
 153 %  Assignment generates the output image from the pruned tree.  The output
 154 %  image consists of two parts: (1)  A color map, which is an array of
 155 %  color descriptions (RGB triples) for each color present in the output
 156 %  image;  (2)  A pixel array, which represents each pixel as an index
 157 %  into the color map array.
 158 %
 159 %  First, the assignment phase makes one pass over the pruned color
 160 %  description tree to establish the image's color map.  For each node
 161 %  with n2  > 0, it divides Sr, Sg, and Sb by n2 .  This produces the mean
 162 %  color of all pixels that classify no lower than this node.  Each of
 163 %  these colors becomes an entry in the color map.
 164 %
 165 %  Finally,  the assignment phase reclassifies each pixel in the pruned
 166 %  tree to identify the deepest node containing the pixel's color.  The
 167 %  pixel's value in the pixel array becomes the index of this node's mean
 168 %  color in the color map.
 169 %
 170 %  This method is based on a similar algorithm written by Paul Raveling.
 171 %
 172 */
 173 \f
 174 /*
 175   Include declarations.
 176 */
 177 #include "magick/studio.h"
 178 #include "magick/cache-view.h"
 179 #include "magick/color.h"
 180 #include "magick/color-private.h"
 181 #include "magick/colormap.h"
 182 #include "magick/colorspace.h"
 183 #include "magick/enhance.h"
 184 #include "magick/exception.h"
 185 #include "magick/exception-private.h"
 186 #include "magick/histogram.h"
 187 #include "magick/image.h"
 188 #include "magick/image-private.h"
 189 #include "magick/list.h"
 190 #include "magick/memory_.h"
 191 #include "magick/monitor.h"
 192 #include "magick/monitor-private.h"
 193 #include "magick/option.h"
 194 #include "magick/pixel-private.h"
 195 #include "magick/quantize.h"
 196 #include "magick/quantum.h"
 197 #include "magick/string_.h"
 198 \f
 199 /*
 200   Define declarations.
 201 */
 202 #if !defined(__APPLE__) && !defined(TARGET_OS_IPHONE)
 203 #define CacheShift  2
 204 #else
 205 #define CacheShift  3
 206 #endif
 207 #define ErrorQueueLength  16
 208 #define MaxNodes  266817
 209 #define MaxTreeDepth  8
 210 #define NodesInAList  1920
 211 \f
 212 /*
 213   Typdef declarations.
 214 */
 215 typedef struct _RealPixelPacket
 216 {
 217   MagickRealType
 218     red,
 219     green,
 220     blue,
 221     opacity;
 222 } RealPixelPacket;
 223
 224 typedef struct _NodeInfo
 225 {
 226   struct _NodeInfo
 227     *parent,
 228     *child[16];
 229
 230   MagickSizeType
 231     number_unique;
 232
 233   RealPixelPacket
 234     total_color;
 235
 236   MagickRealType
 237     quantize_error;
 238
 239   size_t
 240     color_number,
 241     id,
 242     level;
 243 } NodeInfo;
 244
 245 typedef struct _Nodes
 246 {
 247   NodeInfo
 248     *nodes;
 249
 250   struct _Nodes
 251     *next;
 252 } Nodes;
 253
 254 typedef struct _CubeInfo
 255 {
 256   NodeInfo
 257     *root;
 258
 259   size_t
 260     colors,
 261     maximum_colors;
 262
 263   ssize_t
 264     transparent_index;
 265
 266   MagickSizeType
 267     transparent_pixels;
 268
 269   RealPixelPacket
 270     target;
 271
 272   MagickRealType
 273     distance,
 274     pruning_threshold,
 275     next_threshold;
 276
 277   size_t
 278     nodes,
 279     free_nodes,
 280     color_number;
 281
 282   NodeInfo
 283     *next_node;
 284
 285   Nodes
 286     *node_queue;
 287
 288   ssize_t
 289     *cache;
 290
 291   RealPixelPacket
 292     error[ErrorQueueLength];
 293
 294   MagickRealType
 295     weights[ErrorQueueLength];
 296
 297   QuantizeInfo
 298     *quantize_info;
 299
 300   MagickBooleanType
 301     associate_alpha;
 302
 303   ssize_t
 304     x,
 305     y;
 306
 307   size_t
 308     depth;
 309
 310   MagickOffsetType
 311     offset;
 312
 313   MagickSizeType
 314     span;
 315 } CubeInfo;
 316 \f
 317 /*
 318   Method prototypes.
 319 */
 320 static CubeInfo
 321   *GetCubeInfo(const QuantizeInfo *,const size_t,const size_t);
 322
 323 static NodeInfo
 324   *GetNodeInfo(CubeInfo *,const size_t,const size_t,NodeInfo *);
 325
 326 static MagickBooleanType
 327   AssignImageColors(Image *,CubeInfo *),
 328   ClassifyImageColors(CubeInfo *,const Image *,ExceptionInfo *),
 329   DitherImage(Image *,CubeInfo *),
 330   SetGrayscaleImage(Image *);
 331
 332 static size_t
 333   DefineImageColormap(Image *,CubeInfo *,NodeInfo *);
 334
 335 static void
 336   ClosestColor(const Image *,CubeInfo *,const NodeInfo *),
 337   DestroyCubeInfo(CubeInfo *),
 338   PruneLevel(const Image *,CubeInfo *,const NodeInfo *),
 339   PruneToCubeDepth(const Image *,CubeInfo *,const NodeInfo *),
 340   ReduceImageColors(const Image *,CubeInfo *);
 341 \f
 342 /*
 343 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 344 %                                                                             %
 345 %                                                                             %
 346 %                                                                             %
 347 %   A c q u i r e Q u a n t i z e I n f o                                     %
 348 %                                                                             %
 349 %                                                                             %
 350 %                                                                             %
 351 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 352 %
 353 %  AcquireQuantizeInfo() allocates the QuantizeInfo structure.
 354 %
 355 %  The format of the AcquireQuantizeInfo method is:
 356 %
 357 %      QuantizeInfo *AcquireQuantizeInfo(const ImageInfo *image_info)
 358 %
 359 %  A description of each parameter follows:
 360 %
 361 %    o image_info: the image info.
 362 %
 363 */
 364 MagickExport QuantizeInfo *AcquireQuantizeInfo(const ImageInfo *image_info)
 365 {
 366   QuantizeInfo
 367     *quantize_info;
 368
 369   quantize_info=(QuantizeInfo *) AcquireMagickMemory(sizeof(*quantize_info));
 370   if (quantize_info == (QuantizeInfo *) NULL)
 371     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
 372   GetQuantizeInfo(quantize_info);
 373   if (image_info != (ImageInfo *) NULL)
 374     {
 375       const char
 376         *option;
 377
 378       quantize_info->dither=image_info->dither;
 379       option=GetImageOption(image_info,"dither");
 380       if (option != (const char *) NULL)
 381         quantize_info->dither_method=(DitherMethod) ParseMagickOption(
 382           MagickDitherOptions,MagickFalse,option);
 383       quantize_info->measure_error=image_info->verbose;
 384     }
 385   return(quantize_info);
 386 }
 387 \f
 388 /*
 389 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 390 %                                                                             %
 391 %                                                                             %
 392 %                                                                             %
 393 +   A s s i g n I m a g e C o l o r s                                         %
 394 %                                                                             %
 395 %                                                                             %
 396 %                                                                             %
 397 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 398 %
 399 %  AssignImageColors() generates the output image from the pruned tree.  The
 400 %  output image consists of two parts: (1)  A color map, which is an array
 401 %  of color descriptions (RGB triples) for each color present in the
 402 %  output image;  (2)  A pixel array, which represents each pixel as an
 403 %  index into the color map array.
 404 %
 405 %  First, the assignment phase makes one pass over the pruned color
 406 %  description tree to establish the image's color map.  For each node
 407 %  with n2  > 0, it divides Sr, Sg, and Sb by n2 .  This produces the mean
 408 %  color of all pixels that classify no lower than this node.  Each of
 409 %  these colors becomes an entry in the color map.
 410 %
 411 %  Finally,  the assignment phase reclassifies each pixel in the pruned
 412 %  tree to identify the deepest node containing the pixel's color.  The
 413 %  pixel's value in the pixel array becomes the index of this node's mean
 414 %  color in the color map.
 415 %
 416 %  The format of the AssignImageColors() method is:
 417 %
 418 %      MagickBooleanType AssignImageColors(Image *image,CubeInfo *cube_info)
 419 %
 420 %  A description of each parameter follows.
 421 %
 422 %    o image: the image.
 423 %
 424 %    o cube_info: A pointer to the Cube structure.
 425 %
 426 */
 427
 428 static inline void AssociateAlphaPixel(const CubeInfo *cube_info,
 429   const PixelPacket *pixel,RealPixelPacket *alpha_pixel)
 430 {
 431   MagickRealType
 432     alpha;
 433
 434   if ((cube_info->associate_alpha == MagickFalse) ||
 435       (pixel->opacity == OpaqueOpacity))
 436     {
 437       alpha_pixel->red=(MagickRealType) pixel->red;
 438       alpha_pixel->green=(MagickRealType) pixel->green;
 439       alpha_pixel->blue=(MagickRealType) pixel->blue;
 440       alpha_pixel->opacity=(MagickRealType) pixel->opacity;
 441       return;
 442     }
 443   alpha=(MagickRealType) (QuantumScale*(QuantumRange-pixel->opacity));
 444   alpha_pixel->red=alpha*pixel->red;
 445   alpha_pixel->green=alpha*pixel->green;
 446   alpha_pixel->blue=alpha*pixel->blue;
 447   alpha_pixel->opacity=(MagickRealType) pixel->opacity;
 448 }
 449
 450 static inline Quantum ClampToUnsignedQuantum(const MagickRealType value)
 451 {
 452   if (value <= 0.0)
 453     return((Quantum) 0);
 454   if (value >= QuantumRange)
 455     return((Quantum) QuantumRange);
 456   return((Quantum) (value+0.5));
 457 }
 458
 459 static inline size_t ColorToNodeId(const CubeInfo *cube_info,
 460   const RealPixelPacket *pixel,size_t index)
 461 {
 462   size_t
 463     id;
 464
 465   id=(size_t) (
 466     ((ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->red)) >> index) & 0x1) |
 467     ((ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->green)) >> index) & 0x1) << 1 |
 468     ((ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->blue)) >> index) & 0x1) << 2);
 469   if (cube_info->associate_alpha != MagickFalse)
 470     id|=((ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->opacity)) >> index) & 0x1)
 471       << 3;
 472   return(id);
 473 }
 474
 475 static inline MagickBooleanType IsSameColor(const Image *image,
 476   const PixelPacket *p,const PixelPacket *q)
 477 {
 478   if ((p->red != q->red) || (p->green != q->green) || (p->blue != q->blue))
 479     return(MagickFalse);
 480   if ((image->matte != MagickFalse) && (p->opacity != q->opacity))
 481     return(MagickFalse);
 482   return(MagickTrue);
 483 }
 484
 485 static MagickBooleanType AssignImageColors(Image *image,CubeInfo *cube_info)
 486 {
 487 #define AssignImageTag  "Assign/Image"
 488
 489   MagickBooleanType
 490     proceed;
 491
 492   RealPixelPacket
 493     pixel;
 494
 495   register const NodeInfo
 496     *node_info;
 497
 498   register ssize_t
 499     i,
 500     x;
 501
 502   size_t
 503     id,
 504     index;
 505
 506   ssize_t
 507     count,
 508     y;
 509
 510   /*
 511     Allocate image colormap.
 512   */
 513   if ((cube_info->quantize_info->colorspace != UndefinedColorspace) &&
 514       (cube_info->quantize_info->colorspace != CMYKColorspace))
 515     (void) TransformImageColorspace((Image *) image,
 516       cube_info->quantize_info->colorspace);
 517   else
 518     if ((image->colorspace != GRAYColorspace) &&
 519         (image->colorspace != RGBColorspace) &&
 520         (image->colorspace != CMYColorspace))
 521       (void) TransformImageColorspace((Image *) image,RGBColorspace);
 522   if (AcquireImageColormap(image,cube_info->colors) == MagickFalse)
 523     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
 524       image->filename);
 525   image->colors=0;
 526   cube_info->transparent_pixels=0;
 527   cube_info->transparent_index=(-1);
 528   (void) DefineImageColormap(image,cube_info,cube_info->root);
 529   /*
 530     Create a reduced color image.
 531   */
 532   if ((cube_info->quantize_info->dither != MagickFalse) &&
 533       (cube_info->quantize_info->dither_method != NoDitherMethod))
 534     (void) DitherImage(image,cube_info);
 535   else
 536     {
 537       ExceptionInfo
 538         *exception;
 539
 540       CacheView
 541         *image_view;
 542
 543       exception=(&image->exception);
 544       image_view=AcquireCacheView(image);
 545       for (y=0; y < (ssize_t) image->rows; y++)
 546       {
 547         register IndexPacket
 548           *restrict indexes;
 549
 550         register PixelPacket
 551           *restrict q;
 552
 553         q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
 554           exception);
 555         if (q == (PixelPacket *) NULL)
 556           break;
 557         indexes=GetCacheViewAuthenticIndexQueue(image_view);
 558         for (x=0; x < (ssize_t) image->columns; x+=count)
 559         {
 560           /*
 561             Identify the deepest node containing the pixel's color.
 562           */
 563           for (count=1; (x+count) < (ssize_t) image->columns; count++)
 564             if (IsSameColor(image,q,q+count) == MagickFalse)
 565               break;
 566           AssociateAlphaPixel(cube_info,q,&pixel);
 567           node_info=cube_info->root;
 568           for (index=MaxTreeDepth-1; (ssize_t) index > 0; index--)
 569           {
 570             id=ColorToNodeId(cube_info,&pixel,index);
 571             if (node_info->child[id] == (NodeInfo *) NULL)
 572               break;
 573             node_info=node_info->child[id];
 574           }
 575           node_info=node_info->parent;
 576           /*
 577             Find closest color among siblings and their children.
 578           */
 579           cube_info->target=pixel;
 580           cube_info->distance=(MagickRealType) (4.0*(QuantumRange+1.0)*
 581             (QuantumRange+1.0)+1.0);
 582           ClosestColor(image,cube_info,node_info->parent);
 583           index=cube_info->color_number;
 584           for (i=0; i < (ssize_t) count; i++)
 585           {
 586             if (image->storage_class == PseudoClass)
 587               indexes[x+i]=(IndexPacket) index;
 588             if (cube_info->quantize_info->measure_error == MagickFalse)
 589               {
 590                 q->red=image->colormap[index].red;
 591                 q->green=image->colormap[index].green;
 592                 q->blue=image->colormap[index].blue;
 593                 if (cube_info->associate_alpha != MagickFalse)
 594                   q->opacity=image->colormap[index].opacity;
 595               }
 596             q++;
 597           }
 598         }
 599         if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
 600           break;
 601         proceed=SetImageProgress(image,AssignImageTag,(MagickOffsetType) y,
 602           image->rows);
 603         if (proceed == MagickFalse)
 604           break;
 605       }
 606       image_view=DestroyCacheView(image_view);
 607     }
 608   if (cube_info->quantize_info->measure_error != MagickFalse)
 609     (void) GetImageQuantizeError(image);
 610   if ((cube_info->quantize_info->number_colors == 2) &&
 611       (cube_info->quantize_info->colorspace == GRAYColorspace))
 612     {
 613       Quantum
 614         intensity;
 615
 616       register PixelPacket
 617         *restrict q;
 618
 619       /*
 620         Monochrome image.
 621       */
 622       q=image->colormap;
 623       for (i=0; i < (ssize_t) image->colors; i++)
 624       {
 625         intensity=(Quantum) (PixelIntensity(q) < ((MagickRealType)
 626           QuantumRange/2.0) ? 0 : QuantumRange);
 627         q->red=intensity;
 628         q->green=intensity;
 629         q->blue=intensity;
 630         q++;
 631       }
 632     }
 633   (void) SyncImage(image);
 634   if ((cube_info->quantize_info->colorspace != UndefinedColorspace) &&
 635       (cube_info->quantize_info->colorspace != CMYKColorspace))
 636     (void) TransformImageColorspace((Image *) image,RGBColorspace);
 637   return(MagickTrue);
 638 }
 639 \f
 640 /*
 641 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 642 %                                                                             %
 643 %                                                                             %
 644 %                                                                             %
 645 +   C l a s s i f y I m a g e C o l o r s                                     %
 646 %                                                                             %
 647 %                                                                             %
 648 %                                                                             %
 649 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 650 %
 651 %  ClassifyImageColors() begins by initializing a color description tree
 652 %  of sufficient depth to represent each possible input color in a leaf.
 653 %  However, it is impractical to generate a fully-formed color
 654 %  description tree in the storage_class phase for realistic values of
 655 %  Cmax.  If colors components in the input image are quantized to k-bit
 656 %  precision, so that Cmax= 2k-1, the tree would need k levels below the
 657 %  root node to allow representing each possible input color in a leaf.
 658 %  This becomes prohibitive because the tree's total number of nodes is
 659 %  1 + sum(i=1,k,8k).
 660 %
 661 %  A complete tree would require 19,173,961 nodes for k = 8, Cmax = 255.
 662 %  Therefore, to avoid building a fully populated tree, QUANTIZE: (1)
 663 %  Initializes data structures for nodes only as they are needed;  (2)
 664 %  Chooses a maximum depth for the tree as a function of the desired
 665 %  number of colors in the output image (currently log2(colormap size)).
 666 %
 667 %  For each pixel in the input image, storage_class scans downward from
 668 %  the root of the color description tree.  At each level of the tree it
 669 %  identifies the single node which represents a cube in RGB space
 670 %  containing It updates the following data for each such node:
 671 %
 672 %    n1 : Number of pixels whose color is contained in the RGB cube
 673 %    which this node represents;
 674 %
 675 %    n2 : Number of pixels whose color is not represented in a node at
 676 %    lower depth in the tree;  initially,  n2 = 0 for all nodes except
 677 %    leaves of the tree.
 678 %
 679 %    Sr, Sg, Sb : Sums of the red, green, and blue component values for
 680 %    all pixels not classified at a lower depth. The combination of
 681 %    these sums and n2  will ultimately characterize the mean color of a
 682 %    set of pixels represented by this node.
 683 %
 684 %    E: the distance squared in RGB space between each pixel contained
 685 %    within a node and the nodes' center.  This represents the quantization
 686 %    error for a node.
 687 %
 688 %  The format of the ClassifyImageColors() method is:
 689 %
 690 %      MagickBooleanType ClassifyImageColors(CubeInfo *cube_info,
 691 %        const Image *image,ExceptionInfo *exception)
 692 %
 693 %  A description of each parameter follows.
 694 %
 695 %    o cube_info: A pointer to the Cube structure.
 696 %
 697 %    o image: the image.
 698 %
 699 */
 700
 701 static inline void SetAssociatedAlpha(const Image *image,CubeInfo *cube_info)
 702 {
 703   MagickBooleanType
 704     associate_alpha;
 705
 706   associate_alpha=image->matte;
 707   if (cube_info->quantize_info->colorspace == TransparentColorspace)
 708     associate_alpha=MagickFalse;
 709   if ((cube_info->quantize_info->number_colors == 2) &&
 710       (cube_info->quantize_info->colorspace == GRAYColorspace))
 711     associate_alpha=MagickFalse;
 712   cube_info->associate_alpha=associate_alpha;
 713 }
 714
 715 static MagickBooleanType ClassifyImageColors(CubeInfo *cube_info,
 716   const Image *image,ExceptionInfo *exception)
 717 {
 718 #define ClassifyImageTag  "Classify/Image"
 719
 720   CacheView
 721     *image_view;
 722
 723   MagickBooleanType
 724     proceed;
 725
 726   MagickRealType
 727     bisect;
 728
 729   NodeInfo
 730     *node_info;
 731
 732   RealPixelPacket
 733     error,
 734     mid,
 735     midpoint,
 736     pixel;
 737
 738   size_t
 739     count,
 740     id,
 741     index,
 742     level;
 743
 744   ssize_t
 745     y;
 746
 747   /*
 748     Classify the first cube_info->maximum_colors colors to a tree depth of 8.
 749   */
 750   SetAssociatedAlpha(image,cube_info);
 751   if ((cube_info->quantize_info->colorspace != UndefinedColorspace) &&
 752       (cube_info->quantize_info->colorspace != CMYKColorspace))
 753     (void) TransformImageColorspace((Image *) image,
 754       cube_info->quantize_info->colorspace);
 755   else
 756     if ((image->colorspace != GRAYColorspace) &&
 757         (image->colorspace != CMYColorspace) &&
 758         (image->colorspace != RGBColorspace))
 759       (void) TransformImageColorspace((Image *) image,RGBColorspace);
 760   midpoint.red=(MagickRealType) QuantumRange/2.0;
 761   midpoint.green=(MagickRealType) QuantumRange/2.0;
 762   midpoint.blue=(MagickRealType) QuantumRange/2.0;
 763   midpoint.opacity=(MagickRealType) QuantumRange/2.0;
 764   error.opacity=0.0;
 765   image_view=AcquireCacheView(image);
 766   for (y=0; y < (ssize_t) image->rows; y++)
 767   {
 768     register const PixelPacket
 769       *restrict p;
 770
 771     register ssize_t
 772       x;
 773
 774     p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
 775     if (p == (const PixelPacket *) NULL)
 776       break;
 777     if (cube_info->nodes > MaxNodes)
 778       {
 779         /*
 780           Prune one level if the color tree is too large.
 781         */
 782         PruneLevel(image,cube_info,cube_info->root);
 783         cube_info->depth--;
 784       }
 785     for (x=0; x < (ssize_t) image->columns; x+=(ssize_t) count)
 786     {
 787       /*
 788         Start at the root and descend the color cube tree.
 789       */
 790       for (count=1; (x+(ssize_t) count) < (ssize_t) image->columns; count++)
 791         if (IsSameColor(image,p,p+count) == MagickFalse)
 792           break;
 793       AssociateAlphaPixel(cube_info,p,&pixel);
 794       index=MaxTreeDepth-1;
 795       bisect=((MagickRealType) QuantumRange+1.0)/2.0;
 796       mid=midpoint;
 797       node_info=cube_info->root;
 798       for (level=1; level <= MaxTreeDepth; level++)
 799       {
 800         bisect*=0.5;
 801         id=ColorToNodeId(cube_info,&pixel,index);
 802         mid.red+=(id & 1) != 0 ? bisect : -bisect;
 803         mid.green+=(id & 2) != 0 ? bisect : -bisect;
 804         mid.blue+=(id & 4) != 0 ? bisect : -bisect;
 805         mid.opacity+=(id & 8) != 0 ? bisect : -bisect;
 806         if (node_info->child[id] == (NodeInfo *) NULL)
 807           {
 808             /*
 809               Set colors of new node to contain pixel.
 810             */
 811             node_info->child[id]=GetNodeInfo(cube_info,id,level,node_info);
 812             if (node_info->child[id] == (NodeInfo *) NULL)
 813               (void) ThrowMagickException(exception,GetMagickModule(),
 814                 ResourceLimitError,"MemoryAllocationFailed","`%s'",
 815                 image->filename);
 816             if (level == MaxTreeDepth)
 817               cube_info->colors++;
 818           }
 819         /*
 820           Approximate the quantization error represented by this node.
 821         */
 822         node_info=node_info->child[id];
 823         error.red=QuantumScale*(pixel.red-mid.red);
 824         error.green=QuantumScale*(pixel.green-mid.green);
 825         error.blue=QuantumScale*(pixel.blue-mid.blue);
 826         if (cube_info->associate_alpha != MagickFalse)
 827           error.opacity=QuantumScale*(pixel.opacity-mid.opacity);
 828         node_info->quantize_error+=sqrt((double) (count*error.red*error.red+
 829           count*error.green*error.green+count*error.blue*error.blue+
 830           count*error.opacity*error.opacity));
 831         cube_info->root->quantize_error+=node_info->quantize_error;
 832         index--;
 833       }
 834       /*
 835         Sum RGB for this leaf for later derivation of the mean cube color.
 836       */
 837       node_info->number_unique+=count;
 838       node_info->total_color.red+=count*QuantumScale*pixel.red;
 839       node_info->total_color.green+=count*QuantumScale*pixel.green;
 840       node_info->total_color.blue+=count*QuantumScale*pixel.blue;
 841       if (cube_info->associate_alpha != MagickFalse)
 842         node_info->total_color.opacity+=count*QuantumScale*pixel.opacity;
 843       p+=count;
 844     }
 845     if (cube_info->colors > cube_info->maximum_colors)
 846       {
 847         PruneToCubeDepth(image,cube_info,cube_info->root);
 848         break;
 849       }
 850     proceed=SetImageProgress(image,ClassifyImageTag,(MagickOffsetType) y,
 851       image->rows);
 852     if (proceed == MagickFalse)
 853       break;
 854   }
 855   for (y++; y < (ssize_t) image->rows; y++)
 856   {
 857     register const PixelPacket
 858       *restrict p;
 859
 860     register ssize_t
 861       x;
 862
 863     p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
 864     if (p == (const PixelPacket *) NULL)
 865       break;
 866     if (cube_info->nodes > MaxNodes)
 867       {
 868         /*
 869           Prune one level if the color tree is too large.
 870         */
 871         PruneLevel(image,cube_info,cube_info->root);
 872         cube_info->depth--;
 873       }
 874     for (x=0; x < (ssize_t) image->columns; x+=(ssize_t) count)
 875     {
 876       /*
 877         Start at the root and descend the color cube tree.
 878       */
 879       for (count=1; (x+(ssize_t) count) < (ssize_t) image->columns; count++)
 880         if (IsSameColor(image,p,p+count) == MagickFalse)
 881           break;
 882       AssociateAlphaPixel(cube_info,p,&pixel);
 883       index=MaxTreeDepth-1;
 884       bisect=((MagickRealType) QuantumRange+1.0)/2.0;
 885       mid=midpoint;
 886       node_info=cube_info->root;
 887       for (level=1; level <= cube_info->depth; level++)
 888       {
 889         bisect*=0.5;
 890         id=ColorToNodeId(cube_info,&pixel,index);
 891         mid.red+=(id & 1) != 0 ? bisect : -bisect;
 892         mid.green+=(id & 2) != 0 ? bisect : -bisect;
 893         mid.blue+=(id & 4) != 0 ? bisect : -bisect;
 894         mid.opacity+=(id & 8) != 0 ? bisect : -bisect;
 895         if (node_info->child[id] == (NodeInfo *) NULL)
 896           {
 897             /*
 898               Set colors of new node to contain pixel.
 899             */
 900             node_info->child[id]=GetNodeInfo(cube_info,id,level,node_info);
 901             if (node_info->child[id] == (NodeInfo *) NULL)
 902               (void) ThrowMagickException(exception,GetMagickModule(),
 903                 ResourceLimitError,"MemoryAllocationFailed","%s",
 904                 image->filename);
 905             if (level == cube_info->depth)
 906               cube_info->colors++;
 907           }
 908         /*
 909           Approximate the quantization error represented by this node.
 910         */
 911         node_info=node_info->child[id];
 912         error.red=QuantumScale*(pixel.red-mid.red);
 913         error.green=QuantumScale*(pixel.green-mid.green);
 914         error.blue=QuantumScale*(pixel.blue-mid.blue);
 915         if (cube_info->associate_alpha != MagickFalse)
 916           error.opacity=QuantumScale*(pixel.opacity-mid.opacity);
 917         node_info->quantize_error+=sqrt((double) (count*error.red*error.red+
 918           count*error.green*error.green+count*error.blue*error.blue+
 919           count*error.opacity*error.opacity));
 920         cube_info->root->quantize_error+=node_info->quantize_error;
 921         index--;
 922       }
 923       /*
 924         Sum RGB for this leaf for later derivation of the mean cube color.
 925       */
 926       node_info->number_unique+=count;
 927       node_info->total_color.red+=count*QuantumScale*pixel.red;
 928       node_info->total_color.green+=count*QuantumScale*pixel.green;
 929       node_info->total_color.blue+=count*QuantumScale*pixel.blue;
 930       if (cube_info->associate_alpha != MagickFalse)
 931         node_info->total_color.opacity+=count*QuantumScale*pixel.opacity;
 932       p+=count;
 933     }
 934     proceed=SetImageProgress(image,ClassifyImageTag,(MagickOffsetType) y,
 935       image->rows);
 936     if (proceed == MagickFalse)
 937       break;
 938   }
 939   image_view=DestroyCacheView(image_view);
 940   if ((cube_info->quantize_info->colorspace != UndefinedColorspace) &&
 941       (cube_info->quantize_info->colorspace != CMYKColorspace))
 942     (void) TransformImageColorspace((Image *) image,RGBColorspace);
 943   return(MagickTrue);
 944 }
 945 \f
 946 /*
 947 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 948 %                                                                             %
 949 %                                                                             %
 950 %                                                                             %
 951 %   C l o n e Q u a n t i z e I n f o                                         %
 952 %                                                                             %
 953 %                                                                             %
 954 %                                                                             %
 955 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 956 %
 957 %  CloneQuantizeInfo() makes a duplicate of the given quantize info structure,
 958 %  or if quantize info is NULL, a new one.
 959 %
 960 %  The format of the CloneQuantizeInfo method is:
 961 %
 962 %      QuantizeInfo *CloneQuantizeInfo(const QuantizeInfo *quantize_info)
 963 %
 964 %  A description of each parameter follows:
 965 %
 966 %    o clone_info: Method CloneQuantizeInfo returns a duplicate of the given
 967 %      quantize info, or if image info is NULL a new one.
 968 %
 969 %    o quantize_info: a structure of type info.
 970 %
 971 */
 972 MagickExport QuantizeInfo *CloneQuantizeInfo(const QuantizeInfo *quantize_info)
 973 {
 974   QuantizeInfo
 975     *clone_info;
 976
 977   clone_info=(QuantizeInfo *) AcquireMagickMemory(sizeof(*clone_info));
 978   if (clone_info == (QuantizeInfo *) NULL)
 979     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
 980   GetQuantizeInfo(clone_info);
 981   if (quantize_info == (QuantizeInfo *) NULL)
 982     return(clone_info);
 983   clone_info->number_colors=quantize_info->number_colors;
 984   clone_info->tree_depth=quantize_info->tree_depth;
 985   clone_info->dither=quantize_info->dither;
 986   clone_info->dither_method=quantize_info->dither_method;
 987   clone_info->colorspace=quantize_info->colorspace;
 988   clone_info->measure_error=quantize_info->measure_error;
 989   return(clone_info);
 990 }
 991 \f
 992 /*
 993 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 994 %                                                                             %
 995 %                                                                             %
 996 %                                                                             %
 997 +   C l o s e s t C o l o r                                                   %
 998 %                                                                             %
 999 %                                                                             %
1000 %                                                                             %
1001 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1002 %
1003 %  ClosestColor() traverses the color cube tree at a particular node and
1004 %  determines which colormap entry best represents the input color.
1005 %
1006 %  The format of the ClosestColor method is:
1007 %
1008 %      void ClosestColor(const Image *image,CubeInfo *cube_info,
1009 %        const NodeInfo *node_info)
1010 %
1011 %  A description of each parameter follows.
1012 %
1013 %    o image: the image.
1014 %
1015 %    o cube_info: A pointer to the Cube structure.
1016 %
1017 %    o node_info: the address of a structure of type NodeInfo which points to a
1018 %      node in the color cube tree that is to be pruned.
1019 %
1020 */
1021 static void ClosestColor(const Image *image,CubeInfo *cube_info,
1022   const NodeInfo *node_info)
1023 {
1024   register ssize_t
1025     i;
1026
1027   size_t
1028     number_children;
1029
1030   /*
1031     Traverse any children.
1032   */
1033   number_children=cube_info->associate_alpha == MagickFalse ? 8UL : 16UL;
1034   for (i=0; i < (ssize_t) number_children; i++)
1035     if (node_info->child[i] != (NodeInfo *) NULL)
1036       ClosestColor(image,cube_info,node_info->child[i]);
1037   if (node_info->number_unique != 0)
1038     {
1039       MagickRealType
1040         pixel;
1041
1042       register MagickRealType
1043         alpha,
1044         beta,
1045         distance;
1046
1047       register PixelPacket
1048         *restrict p;
1049
1050       register RealPixelPacket
1051         *restrict q;
1052
1053       /*
1054         Determine if this color is "closest".
1055       */
1056       p=image->colormap+node_info->color_number;
1057       q=(&cube_info->target);
1058       alpha=1.0;
1059       beta=1.0;
1060       if (cube_info->associate_alpha != MagickFalse)
1061         {
1062           alpha=(MagickRealType) (QuantumScale*GetAlphaPixelComponent(p));
1063           beta=(MagickRealType) (QuantumScale*GetAlphaPixelComponent(q));
1064         }
1065       pixel=alpha*p->red-beta*q->red;
1066       distance=pixel*pixel;
1067       if (distance <= cube_info->distance)
1068         {
1069           pixel=alpha*p->green-beta*q->green;
1070           distance+=pixel*pixel;
1071           if (distance <= cube_info->distance)
1072             {
1073               pixel=alpha*p->blue-beta*q->blue;
1074               distance+=pixel*pixel;
1075               if (distance <= cube_info->distance)
1076                 {
1077                   pixel=alpha-beta;
1078                   distance+=pixel*pixel;
1079                   if (distance <= cube_info->distance)
1080                     {
1081                       cube_info->distance=distance;
1082                       cube_info->color_number=node_info->color_number;
1083                     }
1084                 }
1085             }
1086         }
1087     }
1088 }
1089 \f
1090 /*
1091 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1092 %                                                                             %
1093 %                                                                             %
1094 %                                                                             %
1095 %   C o m p r e s s I m a g e C o l o r m a p                                 %
1096 %                                                                             %
1097 %                                                                             %
1098 %                                                                             %
1099 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1100 %
1101 %  CompressImageColormap() compresses an image colormap by removing any
1102 %  duplicate or unused color entries.
1103 %
1104 %  The format of the CompressImageColormap method is:
1105 %
1106 %      MagickBooleanType CompressImageColormap(Image *image)
1107 %
1108 %  A description of each parameter follows:
1109 %
1110 %    o image: the image.
1111 %
1112 */
1113 MagickExport MagickBooleanType CompressImageColormap(Image *image)
1114 {
1115   QuantizeInfo
1116     quantize_info;
1117
1118   assert(image != (Image *) NULL);
1119   assert(image->signature == MagickSignature);
1120   if (image->debug != MagickFalse)
1121     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1122   if (IsPaletteImage(image,&image->exception) == MagickFalse)
1123     return(MagickFalse);
1124   GetQuantizeInfo(&quantize_info);
1125   quantize_info.number_colors=image->colors;
1126   quantize_info.tree_depth=MaxTreeDepth;
1127   return(QuantizeImage(&quantize_info,image));
1128 }
1129 \f
1130 /*
1131 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1132 %                                                                             %
1133 %                                                                             %
1134 %                                                                             %
1135 +   D e f i n e I m a g e C o l o r m a p                                     %
1136 %                                                                             %
1137 %                                                                             %
1138 %                                                                             %
1139 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1140 %
1141 %  DefineImageColormap() traverses the color cube tree and notes each colormap
1142 %  entry.  A colormap entry is any node in the color cube tree where the
1143 %  of unique colors is not zero.  DefineImageColormap() returns the number of
1144 %  colors in the image colormap.
1145 %
1146 %  The format of the DefineImageColormap method is:
1147 %
1148 %      size_t DefineImageColormap(Image *image,CubeInfo *cube_info,
1149 %        NodeInfo *node_info)
1150 %
1151 %  A description of each parameter follows.
1152 %
1153 %    o image: the image.
1154 %
1155 %    o cube_info: A pointer to the Cube structure.
1156 %
1157 %    o node_info: the address of a structure of type NodeInfo which points to a
1158 %      node in the color cube tree that is to be pruned.
1159 %
1160 */
1161 static size_t DefineImageColormap(Image *image,CubeInfo *cube_info,
1162   NodeInfo *node_info)
1163 {
1164   register ssize_t
1165     i;
1166
1167   size_t
1168     number_children;
1169
1170   /*
1171     Traverse any children.
1172   */
1173   number_children=cube_info->associate_alpha == MagickFalse ? 8UL : 16UL;
1174   for (i=0; i < (ssize_t) number_children; i++)
1175     if (node_info->child[i] != (NodeInfo *) NULL)
1176       (void) DefineImageColormap(image,cube_info,node_info->child[i]);
1177   if (node_info->number_unique != 0)
1178     {
1179       register MagickRealType
1180         alpha;
1181
1182       register PixelPacket
1183         *restrict q;
1184
1185       /*
1186         Colormap entry is defined by the mean color in this cube.
1187       */
1188       q=image->colormap+image->colors;
1189       alpha=(MagickRealType) ((MagickOffsetType) node_info->number_unique);
1190       alpha=1.0/(fabs(alpha) <= MagickEpsilon ? 1.0 : alpha);
1191       if (cube_info->associate_alpha == MagickFalse)
1192         {
1193           q->red=ClampToQuantum((MagickRealType) (alpha*QuantumRange*
1194             node_info->total_color.red));
1195           q->green=ClampToQuantum((MagickRealType) (alpha*QuantumRange*
1196             node_info->total_color.green));
1197           q->blue=ClampToQuantum((MagickRealType) (alpha*QuantumRange*
1198             node_info->total_color.blue));
1199           SetOpacityPixelComponent(q,OpaqueOpacity);
1200         }
1201       else
1202         {
1203           MagickRealType
1204             opacity;
1205
1206           opacity=(MagickRealType) (alpha*QuantumRange*
1207             node_info->total_color.opacity);
1208           q->opacity=ClampToQuantum(opacity);
1209           if (q->opacity == OpaqueOpacity)
1210             {
1211               q->red=ClampToQuantum((MagickRealType) (alpha*QuantumRange*
1212                 node_info->total_color.red));
1213               q->green=ClampToQuantum((MagickRealType) (alpha*QuantumRange*
1214                 node_info->total_color.green));
1215               q->blue=ClampToQuantum((MagickRealType) (alpha*QuantumRange*
1216                 node_info->total_color.blue));
1217             }
1218           else
1219             {
1220               MagickRealType
1221                 gamma;
1222
1223               gamma=(MagickRealType) (QuantumScale*(QuantumRange-
1224                 (MagickRealType) q->opacity));
1225               gamma=1.0/(fabs(gamma) <= MagickEpsilon ? 1.0 : gamma);
1226               q->red=ClampToQuantum((MagickRealType) (alpha*gamma*QuantumRange*
1227                 node_info->total_color.red));
1228               q->green=ClampToQuantum((MagickRealType) (alpha*gamma*
1229                 QuantumRange*node_info->total_color.green));
1230               q->blue=ClampToQuantum((MagickRealType) (alpha*gamma*QuantumRange*
1231                 node_info->total_color.blue));
1232               if (node_info->number_unique > cube_info->transparent_pixels)
1233                 {
1234                   cube_info->transparent_pixels=node_info->number_unique;
1235                   cube_info->transparent_index=(ssize_t) image->colors;
1236                 }
1237             }
1238         }
1239       node_info->color_number=image->colors++;
1240     }
1241   return(image->colors);
1242 }
1243 \f
1244 /*
1245 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1246 %                                                                             %
1247 %                                                                             %
1248 %                                                                             %
1249 +   D e s t r o y C u b e I n f o                                             %
1250 %                                                                             %
1251 %                                                                             %
1252 %                                                                             %
1253 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1254 %
1255 %  DestroyCubeInfo() deallocates memory associated with an image.
1256 %
1257 %  The format of the DestroyCubeInfo method is:
1258 %
1259 %      DestroyCubeInfo(CubeInfo *cube_info)
1260 %
1261 %  A description of each parameter follows:
1262 %
1263 %    o cube_info: the address of a structure of type CubeInfo.
1264 %
1265 */
1266 static void DestroyCubeInfo(CubeInfo *cube_info)
1267 {
1268   register Nodes
1269     *nodes;
1270
1271   /*
1272     Release color cube tree storage.
1273   */
1274   do
1275   {
1276     nodes=cube_info->node_queue->next;
1277     cube_info->node_queue->nodes=(NodeInfo *) RelinquishMagickMemory(
1278       cube_info->node_queue->nodes);
1279     cube_info->node_queue=(Nodes *) RelinquishMagickMemory(
1280       cube_info->node_queue);
1281     cube_info->node_queue=nodes;
1282   } while (cube_info->node_queue != (Nodes *) NULL);
1283   if (cube_info->cache != (ssize_t *) NULL)
1284     cube_info->cache=(ssize_t *) RelinquishMagickMemory(cube_info->cache);
1285   cube_info->quantize_info=DestroyQuantizeInfo(cube_info->quantize_info);
1286   cube_info=(CubeInfo *) RelinquishMagickMemory(cube_info);
1287 }
1288 \f
1289 /*
1290 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1291 %                                                                             %
1292 %                                                                             %
1293 %                                                                             %
1294 %   D e s t r o y Q u a n t i z e I n f o                                     %
1295 %                                                                             %
1296 %                                                                             %
1297 %                                                                             %
1298 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1299 %
1300 %  DestroyQuantizeInfo() deallocates memory associated with an QuantizeInfo
1301 %  structure.
1302 %
1303 %  The format of the DestroyQuantizeInfo method is:
1304 %
1305 %      QuantizeInfo *DestroyQuantizeInfo(QuantizeInfo *quantize_info)
1306 %
1307 %  A description of each parameter follows:
1308 %
1309 %    o quantize_info: Specifies a pointer to an QuantizeInfo structure.
1310 %
1311 */
1312 MagickExport QuantizeInfo *DestroyQuantizeInfo(QuantizeInfo *quantize_info)
1313 {
1314   (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
1315   assert(quantize_info != (QuantizeInfo *) NULL);
1316   assert(quantize_info->signature == MagickSignature);
1317   quantize_info->signature=(~MagickSignature);
1318   quantize_info=(QuantizeInfo *) RelinquishMagickMemory(quantize_info);
1319   return(quantize_info);
1320 }
1321 \f
1322 /*
1323 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1324 %                                                                             %
1325 %                                                                             %
1326 %                                                                             %
1327 +   D i t h e r I m a g e                                                     %
1328 %                                                                             %
1329 %                                                                             %
1330 %                                                                             %
1331 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1332 %
1333 %  DitherImage() distributes the difference between an original image and
1334 %  the corresponding color reduced algorithm to neighboring pixels using
1335 %  serpentine-scan Floyd-Steinberg error diffusion. DitherImage returns
1336 %  MagickTrue if the image is dithered otherwise MagickFalse.
1337 %
1338 %  The format of the DitherImage method is:
1339 %
1340 %      MagickBooleanType DitherImage(Image *image,CubeInfo *cube_info)
1341 %
1342 %  A description of each parameter follows.
1343 %
1344 %    o image: the image.
1345 %
1346 %    o cube_info: A pointer to the Cube structure.
1347 %
1348 */
1349
1350 static inline ssize_t CacheOffset(CubeInfo *cube_info,
1351   const RealPixelPacket *pixel)
1352 {
1353 #define RedShift(pixel) (((pixel) >> CacheShift) << (0*(8-CacheShift)))
1354 #define GreenShift(pixel) (((pixel) >> CacheShift) << (1*(8-CacheShift)))
1355 #define BlueShift(pixel) (((pixel) >> CacheShift) << (2*(8-CacheShift)))
1356 #define AlphaShift(pixel) (((pixel) >> CacheShift) << (3*(8-CacheShift)))
1357
1358   ssize_t
1359     offset;
1360
1361   offset=(ssize_t)
1362     (RedShift(ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->red))) |
1363     GreenShift(ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->green))) |
1364     BlueShift(ScaleQuantumToChar(ClampToUnsignedQuantum(pixel->blue))));
1365   if (cube_info->associate_alpha != MagickFalse)
1366     offset|=AlphaShift(ScaleQuantumToChar(ClampToUnsignedQuantum(
1367       pixel->opacity)));
1368   return(offset);
1369 }
1370
1371 static MagickBooleanType FloydSteinbergDither(Image *image,CubeInfo *cube_info)
1372 {
1373 #define DitherImageTag  "Dither/Image"
1374
1375   CacheView
1376     *image_view;
1377
1378   ExceptionInfo
1379     *exception;
1380
1381   MagickBooleanType
1382     proceed;
1383
1384   RealPixelPacket
1385     color,
1386     *current,
1387     pixel,
1388     *previous,
1389     *scanlines;
1390
1391   register CubeInfo
1392     *p;
1393
1394   size_t
1395     index;
1396
1397   ssize_t
1398     u,
1399     v,
1400     y;
1401
1402   /*
1403     Distribute quantization error using Floyd-Steinberg.
1404   */
1405   scanlines=(RealPixelPacket *) AcquireQuantumMemory(image->columns,
1406     2*sizeof(*scanlines));
1407   if (scanlines == (RealPixelPacket *) NULL)
1408     return(MagickFalse);
1409   p=cube_info;
1410   exception=(&image->exception);
1411   image_view=AcquireCacheView(image);
1412   for (y=0; y < (ssize_t) image->rows; y++)
1413   {
1414     register IndexPacket
1415       *restrict indexes;
1416
1417     register PixelPacket
1418       *restrict q;
1419
1420     register ssize_t
1421       i,
1422       x;
1423
1424     q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
1425     if (q == (PixelPacket *) NULL)
1426       return(MagickFalse);
1427     indexes=GetCacheViewAuthenticIndexQueue(image_view);
1428     current=scanlines+(y & 0x01)*image->columns;
1429     previous=scanlines+((y+1) & 0x01)*image->columns;
1430     v=(ssize_t) ((y & 0x01) ? -1 : 1);
1431     for (x=0; x < (ssize_t) image->columns; x++)
1432     {
1433       u=(y & 0x01) ? (ssize_t) image->columns-1-x : x;
1434       AssociateAlphaPixel(cube_info,q+u,&pixel);
1435       if (x > 0)
1436         {
1437           pixel.red+=7*current[u-v].red/16;
1438           pixel.green+=7*current[u-v].green/16;
1439           pixel.blue+=7*current[u-v].blue/16;
1440           if (cube_info->associate_alpha != MagickFalse)
1441             pixel.opacity+=7*current[u-v].opacity/16;
1442         }
1443       if (y > 0)
1444         {
1445           if (x < (ssize_t) (image->columns-1))
1446             {
1447               pixel.red+=previous[u+v].red/16;
1448               pixel.green+=previous[u+v].green/16;
1449               pixel.blue+=previous[u+v].blue/16;
1450               if (cube_info->associate_alpha != MagickFalse)
1451                 pixel.opacity+=previous[u+v].opacity/16;
1452             }
1453           pixel.red+=5*previous[u].red/16;
1454           pixel.green+=5*previous[u].green/16;
1455           pixel.blue+=5*previous[u].blue/16;
1456           if (cube_info->associate_alpha != MagickFalse)
1457             pixel.opacity+=5*previous[u].opacity/16;
1458           if (x > 0)
1459             {
1460               pixel.red+=3*previous[u-v].red/16;
1461               pixel.green+=3*previous[u-v].green/16;
1462               pixel.blue+=3*previous[u-v].blue/16;
1463               if (cube_info->associate_alpha != MagickFalse)
1464                 pixel.opacity+=3*previous[u-v].opacity/16;
1465             }
1466         }
1467       pixel.red=(MagickRealType) ClampToUnsignedQuantum(pixel.red);
1468       pixel.green=(MagickRealType) ClampToUnsignedQuantum(pixel.green);
1469       pixel.blue=(MagickRealType) ClampToUnsignedQuantum(pixel.blue);
1470       if (cube_info->associate_alpha != MagickFalse)
1471         pixel.opacity=(MagickRealType) ClampToUnsignedQuantum(pixel.opacity);
1472       i=CacheOffset(cube_info,&pixel);
1473       if (p->cache[i] < 0)
1474         {
1475           register NodeInfo
1476             *node_info;
1477
1478           register size_t
1479             id;
1480
1481           /*
1482             Identify the deepest node containing the pixel's color.
1483           */
1484           node_info=p->root;
1485           for (index=MaxTreeDepth-1; (ssize_t) index > 0; index--)
1486           {
1487             id=ColorToNodeId(cube_info,&pixel,index);
1488             if (node_info->child[id] == (NodeInfo *) NULL)
1489               break;
1490             node_info=node_info->child[id];
1491           }
1492           node_info=node_info->parent;
1493           /*
1494             Find closest color among siblings and their children.
1495           */
1496           p->target=pixel;
1497           p->distance=(MagickRealType) (4.0*(QuantumRange+1.0)*(QuantumRange+
1498             1.0)+1.0);
1499           ClosestColor(image,p,node_info->parent);
1500           p->cache[i]=(ssize_t) p->color_number;
1501         }
1502       /*
1503         Assign pixel to closest colormap entry.
1504       */
1505       index=(size_t) p->cache[i];
1506       if (image->storage_class == PseudoClass)
1507         indexes[u]=(IndexPacket) index;
1508       if (cube_info->quantize_info->measure_error == MagickFalse)
1509         {
1510           (q+u)->red=image->colormap[index].red;
1511           (q+u)->green=image->colormap[index].green;
1512           (q+u)->blue=image->colormap[index].blue;
1513           if (cube_info->associate_alpha != MagickFalse)
1514             (q+u)->opacity=image->colormap[index].opacity;
1515         }
1516       if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
1517         return(MagickFalse);
1518       /*
1519         Store the error.
1520       */
1521       AssociateAlphaPixel(cube_info,image->colormap+index,&color);
1522       current[u].red=pixel.red-color.red;
1523       current[u].green=pixel.green-color.green;
1524       current[u].blue=pixel.blue-color.blue;
1525       if (cube_info->associate_alpha != MagickFalse)
1526         current[u].opacity=pixel.opacity-color.opacity;
1527       proceed=SetImageProgress(image,DitherImageTag,p->offset,p->span);
1528       if (proceed == MagickFalse)
1529         return(MagickFalse);
1530       p->offset++;
1531     }
1532   }
1533   scanlines=(RealPixelPacket *) RelinquishMagickMemory(scanlines);
1534   image_view=DestroyCacheView(image_view);
1535   return(MagickTrue);
1536 }
1537
1538 static MagickBooleanType
1539   RiemersmaDither(Image *,CacheView *,CubeInfo *,const unsigned int);
1540
1541 static void Riemersma(Image *image,CacheView *image_view,CubeInfo *cube_info,
1542   const size_t level,const unsigned int direction)
1543 {
1544   if (level == 1)
1545     switch (direction)
1546     {
1547       case WestGravity:
1548       {
1549         (void) RiemersmaDither(image,image_view,cube_info,EastGravity);
1550         (void) RiemersmaDither(image,image_view,cube_info,SouthGravity);
1551         (void) RiemersmaDither(image,image_view,cube_info,WestGravity);
1552         break;
1553       }
1554       case EastGravity:
1555       {
1556         (void) RiemersmaDither(image,image_view,cube_info,WestGravity);
1557         (void) RiemersmaDither(image,image_view,cube_info,NorthGravity);
1558         (void) RiemersmaDither(image,image_view,cube_info,EastGravity);
1559         break;
1560       }
1561       case NorthGravity:
1562       {
1563         (void) RiemersmaDither(image,image_view,cube_info,SouthGravity);
1564         (void) RiemersmaDither(image,image_view,cube_info,EastGravity);
1565         (void) RiemersmaDither(image,image_view,cube_info,NorthGravity);
1566         break;
1567       }
1568       case SouthGravity:
1569       {
1570         (void) RiemersmaDither(image,image_view,cube_info,NorthGravity);
1571         (void) RiemersmaDither(image,image_view,cube_info,WestGravity);
1572         (void) RiemersmaDither(image,image_view,cube_info,SouthGravity);
1573         break;
1574       }
1575       default:
1576         break;
1577     }
1578   else
1579     switch (direction)
1580     {
1581       case WestGravity:
1582       {
1583         Riemersma(image,image_view,cube_info,level-1,NorthGravity);
1584         (void) RiemersmaDither(image,image_view,cube_info,EastGravity);
1585         Riemersma(image,image_view,cube_info,level-1,WestGravity);
1586         (void) RiemersmaDither(image,image_view,cube_info,SouthGravity);
1587         Riemersma(image,image_view,cube_info,level-1,WestGravity);
1588         (void) RiemersmaDither(image,image_view,cube_info,WestGravity);
1589         Riemersma(image,image_view,cube_info,level-1,SouthGravity);
1590         break;
1591       }
1592       case EastGravity:
1593       {
1594         Riemersma(image,image_view,cube_info,level-1,SouthGravity);
1595         (void) RiemersmaDither(image,image_view,cube_info,WestGravity);
1596         Riemersma(image,image_view,cube_info,level-1,EastGravity);
1597         (void) RiemersmaDither(image,image_view,cube_info,NorthGravity);
1598         Riemersma(image,image_view,cube_info,level-1,EastGravity);
1599         (void) RiemersmaDither(image,image_view,cube_info,EastGravity);
1600         Riemersma(image,image_view,cube_info,level-1,NorthGravity);
1601         break;
1602       }
1603       case NorthGravity:
1604       {
1605         Riemersma(image,image_view,cube_info,level-1,WestGravity);
1606         (void) RiemersmaDither(image,image_view,cube_info,SouthGravity);
1607         Riemersma(image,image_view,cube_info,level-1,NorthGravity);
1608         (void) RiemersmaDither(image,image_view,cube_info,EastGravity);
1609         Riemersma(image,image_view,cube_info,level-1,NorthGravity);
1610         (void) RiemersmaDither(image,image_view,cube_info,NorthGravity);
1611         Riemersma(image,image_view,cube_info,level-1,EastGravity);
1612         break;
1613       }
1614       case SouthGravity:
1615       {
1616         Riemersma(image,image_view,cube_info,level-1,EastGravity);
1617         (void) RiemersmaDither(image,image_view,cube_info,NorthGravity);
1618         Riemersma(image,image_view,cube_info,level-1,SouthGravity);
1619         (void) RiemersmaDither(image,image_view,cube_info,WestGravity);
1620         Riemersma(image,image_view,cube_info,level-1,SouthGravity);
1621         (void) RiemersmaDither(image,image_view,cube_info,SouthGravity);
1622         Riemersma(image,image_view,cube_info,level-1,WestGravity);
1623         break;
1624       }
1625       default:
1626         break;
1627     }
1628 }
1629
1630 static MagickBooleanType RiemersmaDither(Image *image,CacheView *image_view,
1631   CubeInfo *cube_info,const unsigned int direction)
1632 {
1633 #define DitherImageTag  "Dither/Image"
1634
1635   MagickBooleanType
1636     proceed;
1637
1638   RealPixelPacket
1639     color,
1640     pixel;
1641
1642   register CubeInfo
1643     *p;
1644
1645   size_t
1646     index;
1647
1648   p=cube_info;
1649   if ((p->x >= 0) && (p->x < (ssize_t) image->columns) &&
1650       (p->y >= 0) && (p->y < (ssize_t) image->rows))
1651     {
1652       ExceptionInfo
1653         *exception;
1654
1655       register IndexPacket
1656         *restrict indexes;
1657
1658       register PixelPacket
1659         *restrict q;
1660
1661       register ssize_t
1662         i;
1663
1664       /*
1665         Distribute error.
1666       */
1667       exception=(&image->exception);
1668       q=GetCacheViewAuthenticPixels(image_view,p->x,p->y,1,1,exception);
1669       if (q == (PixelPacket *) NULL)
1670         return(MagickFalse);
1671       indexes=GetCacheViewAuthenticIndexQueue(image_view);
1672       AssociateAlphaPixel(cube_info,q,&pixel);
1673       for (i=0; i < ErrorQueueLength; i++)
1674       {
1675         pixel.red+=p->weights[i]*p->error[i].red;
1676         pixel.green+=p->weights[i]*p->error[i].green;
1677         pixel.blue+=p->weights[i]*p->error[i].blue;
1678         if (cube_info->associate_alpha != MagickFalse)
1679           pixel.opacity+=p->weights[i]*p->error[i].opacity;
1680       }
1681       pixel.red=(MagickRealType) ClampToUnsignedQuantum(pixel.red);
1682       pixel.green=(MagickRealType) ClampToUnsignedQuantum(pixel.green);
1683       pixel.blue=(MagickRealType) ClampToUnsignedQuantum(pixel.blue);
1684       if (cube_info->associate_alpha != MagickFalse)
1685         pixel.opacity=(MagickRealType) ClampToUnsignedQuantum(pixel.opacity);
1686       i=CacheOffset(cube_info,&pixel);
1687       if (p->cache[i] < 0)
1688         {
1689           register NodeInfo
1690             *node_info;
1691
1692           register size_t
1693             id;
1694
1695           /*
1696             Identify the deepest node containing the pixel's color.
1697           */
1698           node_info=p->root;
1699           for (index=MaxTreeDepth-1; (ssize_t) index > 0; index--)
1700           {
1701             id=ColorToNodeId(cube_info,&pixel,index);
1702             if (node_info->child[id] == (NodeInfo *) NULL)
1703               break;
1704             node_info=node_info->child[id];
1705           }
1706           node_info=node_info->parent;
1707           /*
1708             Find closest color among siblings and their children.
1709           */
1710           p->target=pixel;
1711           p->distance=(MagickRealType) (4.0*(QuantumRange+1.0)*((MagickRealType)
1712             QuantumRange+1.0)+1.0);
1713           ClosestColor(image,p,node_info->parent);
1714           p->cache[i]=(ssize_t) p->color_number;
1715         }
1716       /*
1717         Assign pixel to closest colormap entry.
1718       */
1719       index=(size_t) (1*p->cache[i]);
1720       if (image->storage_class == PseudoClass)
1721         *indexes=(IndexPacket) index;
1722       if (cube_info->quantize_info->measure_error == MagickFalse)
1723         {
1724           q->red=image->colormap[index].red;
1725           q->green=image->colormap[index].green;
1726           q->blue=image->colormap[index].blue;
1727           if (cube_info->associate_alpha != MagickFalse)
1728             q->opacity=image->colormap[index].opacity;
1729         }
1730       if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
1731         return(MagickFalse);
1732       /*
1733         Propagate the error as the last entry of the error queue.
1734       */
1735       (void) CopyMagickMemory(p->error,p->error+1,(ErrorQueueLength-1)*
1736         sizeof(p->error[0]));
1737       AssociateAlphaPixel(cube_info,image->colormap+index,&color);
1738       p->error[ErrorQueueLength-1].red=pixel.red-color.red;
1739       p->error[ErrorQueueLength-1].green=pixel.green-color.green;
1740       p->error[ErrorQueueLength-1].blue=pixel.blue-color.blue;
1741       if (cube_info->associate_alpha != MagickFalse)
1742         p->error[ErrorQueueLength-1].opacity=pixel.opacity-color.opacity;
1743       proceed=SetImageProgress(image,DitherImageTag,p->offset,p->span);
1744       if (proceed == MagickFalse)
1745         return(MagickFalse);
1746       p->offset++;
1747     }
1748   switch (direction)
1749   {
1750     case WestGravity: p->x--; break;
1751     case EastGravity: p->x++; break;
1752     case NorthGravity: p->y--; break;
1753     case SouthGravity: p->y++; break;
1754   }
1755   return(MagickTrue);
1756 }
1757
1758 static inline ssize_t MagickMax(const ssize_t x,const ssize_t y)
1759 {
1760   if (x > y)
1761     return(x);
1762   return(y);
1763 }
1764
1765 static inline ssize_t MagickMin(const ssize_t x,const ssize_t y)
1766 {
1767   if (x < y)
1768     return(x);
1769   return(y);
1770 }
1771
1772 static MagickBooleanType DitherImage(Image *image,CubeInfo *cube_info)
1773 {
1774   CacheView
1775     *image_view;
1776
1777   MagickBooleanType
1778     status;
1779
1780   register ssize_t
1781     i;
1782
1783   size_t
1784     depth;
1785
1786   if (cube_info->quantize_info->dither_method == FloydSteinbergDitherMethod)
1787     return(FloydSteinbergDither(image,cube_info));
1788   /*
1789     Distribute quantization error along a Hilbert curve.
1790   */
1791   (void) ResetMagickMemory(cube_info->error,0,ErrorQueueLength*
1792     sizeof(*cube_info->error));
1793   cube_info->x=0;
1794   cube_info->y=0;
1795   i=MagickMax((ssize_t) image->columns,(ssize_t) image->rows);
1796   for (depth=1; i != 0; depth++)
1797     i>>=1;
1798   if ((ssize_t) (1L << depth) < MagickMax((ssize_t) image->columns,(ssize_t) image->rows))
1799     depth++;
1800   cube_info->offset=0;
1801   cube_info->span=(MagickSizeType) image->columns*image->rows;
1802   image_view=AcquireCacheView(image);
1803   if (depth > 1)
1804     Riemersma(image,image_view,cube_info,depth-1,NorthGravity);
1805   status=RiemersmaDither(image,image_view,cube_info,ForgetGravity);
1806   image_view=DestroyCacheView(image_view);
1807   return(status);
1808 }
1809 \f
1810 /*
1811 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1812 %                                                                             %
1813 %                                                                             %
1814 %                                                                             %
1815 +   G e t C u b e I n f o                                                     %
1816 %                                                                             %
1817 %                                                                             %
1818 %                                                                             %
1819 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1820 %
1821 %  GetCubeInfo() initialize the Cube data structure.
1822 %
1823 %  The format of the GetCubeInfo method is:
1824 %
1825 %      CubeInfo GetCubeInfo(const QuantizeInfo *quantize_info,
1826 %        const size_t depth,const size_t maximum_colors)
1827 %
1828 %  A description of each parameter follows.
1829 %
1830 %    o quantize_info: Specifies a pointer to an QuantizeInfo structure.
1831 %
1832 %    o depth: Normally, this integer value is zero or one.  A zero or
1833 %      one tells Quantize to choose a optimal tree depth of Log4(number_colors).
1834 %      A tree of this depth generally allows the best representation of the
1835 %      reference image with the least amount of memory and the fastest
1836 %      computational speed.  In some cases, such as an image with low color
1837 %      dispersion (a few number of colors), a value other than
1838 %      Log4(number_colors) is required.  To expand the color tree completely,
1839 %      use a value of 8.
1840 %
1841 %    o maximum_colors: maximum colors.
1842 %
1843 */
1844 static CubeInfo *GetCubeInfo(const QuantizeInfo *quantize_info,
1845   const size_t depth,const size_t maximum_colors)
1846 {
1847   CubeInfo
1848     *cube_info;
1849
1850   MagickRealType
1851     sum,
1852     weight;
1853
1854   register ssize_t
1855     i;
1856
1857   size_t
1858     length;
1859
1860   /*
1861     Initialize tree to describe color cube_info.
1862   */
1863   cube_info=(CubeInfo *) AcquireMagickMemory(sizeof(*cube_info));
1864   if (cube_info == (CubeInfo *) NULL)
1865     return((CubeInfo *) NULL);
1866   (void) ResetMagickMemory(cube_info,0,sizeof(*cube_info));
1867   cube_info->depth=depth;
1868   if (cube_info->depth > MaxTreeDepth)
1869     cube_info->depth=MaxTreeDepth;
1870   if (cube_info->depth < 2)
1871     cube_info->depth=2;
1872   cube_info->maximum_colors=maximum_colors;
1873   /*
1874     Initialize root node.
1875   */
1876   cube_info->root=GetNodeInfo(cube_info,0,0,(NodeInfo *) NULL);
1877   if (cube_info->root == (NodeInfo *) NULL)
1878     return((CubeInfo *) NULL);
1879   cube_info->root->parent=cube_info->root;
1880   cube_info->quantize_info=CloneQuantizeInfo(quantize_info);
1881   if (cube_info->quantize_info->dither == MagickFalse)
1882     return(cube_info);
1883   /*
1884     Initialize dither resources.
1885   */
1886   length=(size_t) (1UL << (4*(8-CacheShift)));
1887   cube_info->cache=(ssize_t *) AcquireQuantumMemory(length,
1888     sizeof(*cube_info->cache));
1889   if (cube_info->cache == (ssize_t *) NULL)
1890     return((CubeInfo *) NULL);
1891   /*
1892     Initialize color cache.
1893   */
1894   for (i=0; i < (ssize_t) length; i++)
1895     cube_info->cache[i]=(-1);
1896   /*
1897     Distribute weights along a curve of exponential decay.
1898   */
1899   weight=1.0;
1900   for (i=0; i < ErrorQueueLength; i++)
1901   {
1902     cube_info->weights[ErrorQueueLength-i-1]=1.0/weight;
1903     weight*=exp(log(((double) QuantumRange+1.0))/(ErrorQueueLength-1.0));
1904   }
1905   /*
1906     Normalize the weighting factors.
1907   */
1908   weight=0.0;
1909   for (i=0; i < ErrorQueueLength; i++)
1910     weight+=cube_info->weights[i];
1911   sum=0.0;
1912   for (i=0; i < ErrorQueueLength; i++)
1913   {
1914     cube_info->weights[i]/=weight;
1915     sum+=cube_info->weights[i];
1916   }
1917   cube_info->weights[0]+=1.0-sum;
1918   return(cube_info);
1919 }
1920 \f
1921 /*
1922 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1923 %                                                                             %
1924 %                                                                             %
1925 %                                                                             %
1926 +   G e t N o d e I n f o                                                     %
1927 %                                                                             %
1928 %                                                                             %
1929 %                                                                             %
1930 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1931 %
1932 %  GetNodeInfo() allocates memory for a new node in the color cube tree and
1933 %  presets all fields to zero.
1934 %
1935 %  The format of the GetNodeInfo method is:
1936 %
1937 %      NodeInfo *GetNodeInfo(CubeInfo *cube_info,const size_t id,
1938 %        const size_t level,NodeInfo *parent)
1939 %
1940 %  A description of each parameter follows.
1941 %
1942 %    o node: The GetNodeInfo method returns a pointer to a queue of nodes.
1943 %
1944 %    o id: Specifies the child number of the node.
1945 %
1946 %    o level: Specifies the level in the storage_class the node resides.
1947 %
1948 */
1949 static NodeInfo *GetNodeInfo(CubeInfo *cube_info,const size_t id,
1950   const size_t level,NodeInfo *parent)
1951 {
1952   NodeInfo
1953     *node_info;
1954
1955   if (cube_info->free_nodes == 0)
1956     {
1957       Nodes
1958         *nodes;
1959
1960       /*
1961         Allocate a new queue of nodes.
1962       */
1963       nodes=(Nodes *) AcquireMagickMemory(sizeof(*nodes));
1964       if (nodes == (Nodes *) NULL)
1965         return((NodeInfo *) NULL);
1966       nodes->nodes=(NodeInfo *) AcquireQuantumMemory(NodesInAList,
1967         sizeof(*nodes->nodes));
1968       if (nodes->nodes == (NodeInfo *) NULL)
1969         return((NodeInfo *) NULL);
1970       nodes->next=cube_info->node_queue;
1971       cube_info->node_queue=nodes;
1972       cube_info->next_node=nodes->nodes;
1973       cube_info->free_nodes=NodesInAList;
1974     }
1975   cube_info->nodes++;
1976   cube_info->free_nodes--;
1977   node_info=cube_info->next_node++;
1978   (void) ResetMagickMemory(node_info,0,sizeof(*node_info));
1979   node_info->parent=parent;
1980   node_info->id=id;
1981   node_info->level=level;
1982   return(node_info);
1983 }
1984 \f
1985 /*
1986 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1987 %                                                                             %
1988 %                                                                             %
1989 %                                                                             %
1990 %  G e t I m a g e Q u a n t i z e E r r o r                                  %
1991 %                                                                             %
1992 %                                                                             %
1993 %                                                                             %
1994 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1995 %
1996 %  GetImageQuantizeError() measures the difference between the original
1997 %  and quantized images.  This difference is the total quantization error.
1998 %  The error is computed by summing over all pixels in an image the distance
1999 %  squared in RGB space between each reference pixel value and its quantized
2000 %  value.  These values are computed:
2001 %
2002 %    o mean_error_per_pixel:  This value is the mean error for any single
2003 %      pixel in the image.
2004 %
2005 %    o normalized_mean_square_error:  This value is the normalized mean
2006 %      quantization error for any single pixel in the image.  This distance
2007 %      measure is normalized to a range between 0 and 1.  It is independent
2008 %      of the range of red, green, and blue values in the image.
2009 %
2010 %    o normalized_maximum_square_error:  Thsi value is the normalized
2011 %      maximum quantization error for any single pixel in the image.  This
2012 %      distance measure is normalized to a range between 0 and 1.  It is
2013 %      independent of the range of red, green, and blue values in your image.
2014 %
2015 %  The format of the GetImageQuantizeError method is:
2016 %
2017 %      MagickBooleanType GetImageQuantizeError(Image *image)
2018 %
2019 %  A description of each parameter follows.
2020 %
2021 %    o image: the image.
2022 %
2023 */
2024 MagickExport MagickBooleanType GetImageQuantizeError(Image *image)
2025 {
2026   CacheView
2027     *image_view;
2028
2029   ExceptionInfo
2030     *exception;
2031
2032   IndexPacket
2033     *indexes;
2034
2035   MagickRealType
2036     alpha,
2037     area,
2038     beta,
2039     distance,
2040     maximum_error,
2041     mean_error,
2042     mean_error_per_pixel;
2043
2044   size_t
2045     index;
2046
2047   ssize_t
2048     y;
2049
2050   assert(image != (Image *) NULL);
2051   assert(image->signature == MagickSignature);
2052   if (image->debug != MagickFalse)
2053     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
2054   image->total_colors=GetNumberColors(image,(FILE *) NULL,&image->exception);
2055   (void) ResetMagickMemory(&image->error,0,sizeof(image->error));
2056   if (image->storage_class == DirectClass)
2057     return(MagickTrue);
2058   alpha=1.0;
2059   beta=1.0;
2060   area=3.0*image->columns*image->rows;
2061   maximum_error=0.0;
2062   mean_error_per_pixel=0.0;
2063   mean_error=0.0;
2064   exception=(&image->exception);
2065   image_view=AcquireCacheView(image);
2066   for (y=0; y < (ssize_t) image->rows; y++)
2067   {
2068     register const PixelPacket
2069       *restrict p;
2070
2071     register ssize_t
2072       x;
2073
2074     p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
2075     if (p == (const PixelPacket *) NULL)
2076       break;
2077     indexes=GetCacheViewAuthenticIndexQueue(image_view);
2078     for (x=0; x < (ssize_t) image->columns; x++)
2079     {
2080       index=1UL*indexes[x];
2081       if (image->matte != MagickFalse)
2082         {
2083           alpha=(MagickRealType) (QuantumScale*(GetAlphaPixelComponent(p)));
2084           beta=(MagickRealType) (QuantumScale*(QuantumRange-
2085             image->colormap[index].opacity));
2086         }
2087       distance=fabs(alpha*p->red-beta*image->colormap[index].red);
2088       mean_error_per_pixel+=distance;
2089       mean_error+=distance*distance;
2090       if (distance > maximum_error)
2091         maximum_error=distance;
2092       distance=fabs(alpha*p->green-beta*image->colormap[index].green);
2093       mean_error_per_pixel+=distance;
2094       mean_error+=distance*distance;
2095       if (distance > maximum_error)
2096         maximum_error=distance;
2097       distance=fabs(alpha*p->blue-beta*image->colormap[index].blue);
2098       mean_error_per_pixel+=distance;
2099       mean_error+=distance*distance;
2100       if (distance > maximum_error)
2101         maximum_error=distance;
2102       p++;
2103     }
2104   }
2105   image_view=DestroyCacheView(image_view);
2106   image->error.mean_error_per_pixel=(double) mean_error_per_pixel/area;
2107   image->error.normalized_mean_error=(double) QuantumScale*QuantumScale*
2108     mean_error/area;
2109   image->error.normalized_maximum_error=(double) QuantumScale*maximum_error;
2110   return(MagickTrue);
2111 }
2112 \f
2113 /*
2114 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2115 %                                                                             %
2116 %                                                                             %
2117 %                                                                             %
2118 %   G e t Q u a n t i z e I n f o                                             %
2119 %                                                                             %
2120 %                                                                             %
2121 %                                                                             %
2122 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2123 %
2124 %  GetQuantizeInfo() initializes the QuantizeInfo structure.
2125 %
2126 %  The format of the GetQuantizeInfo method is:
2127 %
2128 %      GetQuantizeInfo(QuantizeInfo *quantize_info)
2129 %
2130 %  A description of each parameter follows:
2131 %
2132 %    o quantize_info: Specifies a pointer to a QuantizeInfo structure.
2133 %
2134 */
2135 MagickExport void GetQuantizeInfo(QuantizeInfo *quantize_info)
2136 {
2137   (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
2138   assert(quantize_info != (QuantizeInfo *) NULL);
2139   (void) ResetMagickMemory(quantize_info,0,sizeof(*quantize_info));
2140   quantize_info->number_colors=256;
2141   quantize_info->dither=MagickTrue;
2142   quantize_info->dither_method=RiemersmaDitherMethod;
2143   quantize_info->colorspace=UndefinedColorspace;
2144   quantize_info->measure_error=MagickFalse;
2145   quantize_info->signature=MagickSignature;
2146 }
2147 \f
2148 /*
2149 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2150 %                                                                             %
2151 %                                                                             %
2152 %                                                                             %
2153 %     P o s t e r i z e I m a g e C h a n n e l                               %
2154 %                                                                             %
2155 %                                                                             %
2156 %                                                                             %
2157 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2158 %
2159 %  PosterizeImage() reduces the image to a limited number of colors for a
2160 %  "poster" effect.
2161 %
2162 %  The format of the PosterizeImage method is:
2163 %
2164 %      MagickBooleanType PosterizeImage(Image *image,const size_t levels,
2165 %        const MagickBooleanType dither)
2166 %      MagickBooleanType PosterizeImageChannel(Image *image,
2167 %        const ChannelType channel,const size_t levels,
2168 %        const MagickBooleanType dither)
2169 %
2170 %  A description of each parameter follows:
2171 %
2172 %    o image: Specifies a pointer to an Image structure.
2173 %
2174 %    o levels: Number of color levels allowed in each channel.  Very low values
2175 %      (2, 3, or 4) have the most visible effect.
2176 %
2177 %    o dither: Set this integer value to something other than zero to dither
2178 %      the mapped image.
2179 %
2180 */
2181
2182 static inline ssize_t MagickRound(MagickRealType x)
2183 {
2184   /*
2185     Round the fraction to nearest integer.
2186   */
2187   if (x >= 0.0)
2188     return((ssize_t) (x+0.5));
2189   return((ssize_t) (x-0.5));
2190 }
2191
2192 MagickExport MagickBooleanType PosterizeImage(Image *image,const size_t levels,
2193   const MagickBooleanType dither)
2194 {
2195   MagickBooleanType
2196     status;
2197
2198   status=PosterizeImageChannel(image,DefaultChannels,levels,dither);
2199   return(status);
2200 }
2201
2202 MagickExport MagickBooleanType PosterizeImageChannel(Image *image,
2203   const ChannelType channel,const size_t levels,const MagickBooleanType dither)
2204 {
2205 #define PosterizeImageTag  "Posterize/Image"
2206 #define PosterizePixel(pixel) (Quantum) (QuantumRange*(MagickRound( \
2207   QuantumScale*pixel*(levels-1)))/(levels-1))
2208
2209   CacheView
2210     *image_view;
2211
2212   ExceptionInfo
2213     *exception;
2214
2215   MagickBooleanType
2216     status;
2217
2218   MagickOffsetType
2219     progress;
2220
2221   QuantizeInfo
2222     *quantize_info;
2223
2224   register ssize_t
2225     i;
2226
2227   ssize_t
2228     y;
2229
2230   assert(image != (Image *) NULL);
2231   assert(image->signature == MagickSignature);
2232   if (image->debug != MagickFalse)
2233     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
2234   if (image->storage_class == PseudoClass)
2235 #if defined(MAGICKCORE_OPENMP_SUPPORT)
2236   #pragma omp parallel for schedule(dynamic,4) shared(progress,status)
2237 #endif
2238     for (i=0; i < (ssize_t) image->colors; i++)
2239     {
2240       /*
2241         Posterize colormap.
2242       */
2243       if ((channel & RedChannel) != 0)
2244         image->colormap[i].red=PosterizePixel(image->colormap[i].red);
2245       if ((channel & GreenChannel) != 0)
2246         image->colormap[i].green=PosterizePixel(image->colormap[i].green);
2247       if ((channel & BlueChannel) != 0)
2248         image->colormap[i].blue=PosterizePixel(image->colormap[i].blue);
2249       if ((channel & OpacityChannel) != 0)
2250         image->colormap[i].opacity=PosterizePixel(image->colormap[i].opacity);
2251     }
2252   /*
2253     Posterize image.
2254   */
2255   status=MagickTrue;
2256   progress=0;
2257   exception=(&image->exception);
2258   image_view=AcquireCacheView(image);
2259 #if defined(MAGICKCORE_OPENMP_SUPPORT)
2260   #pragma omp parallel for schedule(dynamic,4) shared(progress,status)
2261 #endif
2262   for (y=0; y < (ssize_t) image->rows; y++)
2263   {
2264     register IndexPacket
2265       *restrict indexes;
2266
2267     register PixelPacket
2268       *restrict q;
2269
2270     register ssize_t
2271       x;
2272
2273     if (status == MagickFalse)
2274       continue;
2275     q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
2276     if (q == (PixelPacket *) NULL)
2277       {
2278         status=MagickFalse;
2279         continue;
2280       }
2281     indexes=GetCacheViewAuthenticIndexQueue(image_view);
2282     for (x=0; x < (ssize_t) image->columns; x++)
2283     {
2284       if ((channel & RedChannel) != 0)
2285         q->red=PosterizePixel(q->red);
2286       if ((channel & GreenChannel) != 0)
2287         q->green=PosterizePixel(q->green);
2288       if ((channel & BlueChannel) != 0)
2289         q->blue=PosterizePixel(q->blue);
2290       if (((channel & OpacityChannel) != 0) &&
2291           (image->matte == MagickTrue))
2292         q->opacity=PosterizePixel(q->opacity);
2293       if (((channel & IndexChannel) != 0) &&
2294           (image->colorspace == CMYKColorspace))
2295         indexes[x]=PosterizePixel(indexes[x]);
2296       q++;
2297     }
2298     if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
2299       status=MagickFalse;
2300     if (image->progress_monitor != (MagickProgressMonitor) NULL)
2301       {
2302         MagickBooleanType
2303           proceed;
2304
2305 #if defined(MAGICKCORE_OPENMP_SUPPORT)
2306   #pragma omp critical (MagickCore_PosterizeImageChannel)
2307 #endif
2308         proceed=SetImageProgress(image,PosterizeImageTag,progress++,
2309           image->rows);
2310         if (proceed == MagickFalse)
2311           status=MagickFalse;
2312       }
2313   }
2314   image_view=DestroyCacheView(image_view);
2315   quantize_info=AcquireQuantizeInfo((ImageInfo *) NULL);
2316   quantize_info->number_colors=(size_t) MagickMin((ssize_t) levels*levels*
2317     levels,MaxColormapSize+1);
2318   quantize_info->dither=dither;
2319   status=QuantizeImage(quantize_info,image);
2320   quantize_info=DestroyQuantizeInfo(quantize_info);
2321   return(status);
2322 }
2323 \f
2324 /*
2325 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2326 %                                                                             %
2327 %                                                                             %
2328 %                                                                             %
2329 +   P r u n e C h i l d                                                       %
2330 %                                                                             %
2331 %                                                                             %
2332 %                                                                             %
2333 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2334 %
2335 %  PruneChild() deletes the given node and merges its statistics into its
2336 %  parent.
2337 %
2338 %  The format of the PruneSubtree method is:
2339 %
2340 %      PruneChild(const Image *image,CubeInfo *cube_info,
2341 %        const NodeInfo *node_info)
2342 %
2343 %  A description of each parameter follows.
2344 %
2345 %    o image: the image.
2346 %
2347 %    o cube_info: A pointer to the Cube structure.
2348 %
2349 %    o node_info: pointer to node in color cube tree that is to be pruned.
2350 %
2351 */
2352 static void PruneChild(const Image *image,CubeInfo *cube_info,
2353   const NodeInfo *node_info)
2354 {
2355   NodeInfo
2356     *parent;
2357
2358   register ssize_t
2359     i;
2360
2361   size_t
2362     number_children;
2363
2364   /*
2365     Traverse any children.
2366   */
2367   number_children=cube_info->associate_alpha == MagickFalse ? 8UL : 16UL;
2368   for (i=0; i < (ssize_t) number_children; i++)
2369     if (node_info->child[i] != (NodeInfo *) NULL)
2370       PruneChild(image,cube_info,node_info->child[i]);
2371   /*
2372     Merge color statistics into parent.
2373   */
2374   parent=node_info->parent;
2375   parent->number_unique+=node_info->number_unique;
2376   parent->total_color.red+=node_info->total_color.red;
2377   parent->total_color.green+=node_info->total_color.green;
2378   parent->total_color.blue+=node_info->total_color.blue;
2379   parent->total_color.opacity+=node_info->total_color.opacity;
2380   parent->child[node_info->id]=(NodeInfo *) NULL;
2381   cube_info->nodes--;
2382 }
2383 \f
2384 /*
2385 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2386 %                                                                             %
2387 %                                                                             %
2388 %                                                                             %
2389 +  P r u n e L e v e l                                                        %
2390 %                                                                             %
2391 %                                                                             %
2392 %                                                                             %
2393 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2394 %
2395 %  PruneLevel() deletes all nodes at the bottom level of the color tree merging
2396 %  their color statistics into their parent node.
2397 %
2398 %  The format of the PruneLevel method is:
2399 %
2400 %      PruneLevel(const Image *image,CubeInfo *cube_info,
2401 %        const NodeInfo *node_info)
2402 %
2403 %  A description of each parameter follows.
2404 %
2405 %    o image: the image.
2406 %
2407 %    o cube_info: A pointer to the Cube structure.
2408 %
2409 %    o node_info: pointer to node in color cube tree that is to be pruned.
2410 %
2411 */
2412 static void PruneLevel(const Image *image,CubeInfo *cube_info,
2413   const NodeInfo *node_info)
2414 {
2415   register ssize_t
2416     i;
2417
2418   size_t
2419     number_children;
2420
2421   /*
2422     Traverse any children.
2423   */
2424   number_children=cube_info->associate_alpha == MagickFalse ? 8UL : 16UL;
2425   for (i=0; i < (ssize_t) number_children; i++)
2426     if (node_info->child[i] != (NodeInfo *) NULL)
2427       PruneLevel(image,cube_info,node_info->child[i]);
2428   if (node_info->level == cube_info->depth)
2429     PruneChild(image,cube_info,node_info);
2430 }
2431 \f
2432 /*
2433 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2434 %                                                                             %
2435 %                                                                             %
2436 %                                                                             %
2437 +  P r u n e T o C u b e D e p t h                                            %
2438 %                                                                             %
2439 %                                                                             %
2440 %                                                                             %
2441 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2442 %
2443 %  PruneToCubeDepth() deletes any nodes at a depth greater than
2444 %  cube_info->depth while merging their color statistics into their parent
2445 %  node.
2446 %
2447 %  The format of the PruneToCubeDepth method is:
2448 %
2449 %      PruneToCubeDepth(const Image *image,CubeInfo *cube_info,
2450 %        const NodeInfo *node_info)
2451 %
2452 %  A description of each parameter follows.
2453 %
2454 %    o cube_info: A pointer to the Cube structure.
2455 %
2456 %    o node_info: pointer to node in color cube tree that is to be pruned.
2457 %
2458 */
2459 static void PruneToCubeDepth(const Image *image,CubeInfo *cube_info,
2460   const NodeInfo *node_info)
2461 {
2462   register ssize_t
2463     i;
2464
2465   size_t
2466     number_children;
2467
2468   /*
2469     Traverse any children.
2470   */
2471   number_children=cube_info->associate_alpha == MagickFalse ? 8UL : 16UL;
2472   for (i=0; i < (ssize_t) number_children; i++)
2473     if (node_info->child[i] != (NodeInfo *) NULL)
2474       PruneToCubeDepth(image,cube_info,node_info->child[i]);
2475   if (node_info->level > cube_info->depth)
2476     PruneChild(image,cube_info,node_info);
2477 }
2478 \f
2479 /*
2480 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2481 %                                                                             %
2482 %                                                                             %
2483 %                                                                             %
2484 %  Q u a n t i z e I m a g e                                                  %
2485 %                                                                             %
2486 %                                                                             %
2487 %                                                                             %
2488 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2489 %
2490 %  QuantizeImage() analyzes the colors within a reference image and chooses a
2491 %  fixed number of colors to represent the image.  The goal of the algorithm
2492 %  is to minimize the color difference between the input and output image while
2493 %  minimizing the processing time.
2494 %
2495 %  The format of the QuantizeImage method is:
2496 %
2497 %      MagickBooleanType QuantizeImage(const QuantizeInfo *quantize_info,
2498 %        Image *image)
2499 %
2500 %  A description of each parameter follows:
2501 %
2502 %    o quantize_info: Specifies a pointer to an QuantizeInfo structure.
2503 %
2504 %    o image: the image.
2505 %
2506 */
2507 static MagickBooleanType DirectToColormapImage(Image *image,
2508   ExceptionInfo *exception)
2509 {
2510   CacheView
2511     *image_view;
2512
2513   MagickBooleanType
2514     status;
2515
2516   register ssize_t
2517     i;
2518
2519   size_t
2520     number_colors;
2521
2522   ssize_t
2523     y;
2524
2525   status=MagickTrue;
2526   number_colors=(size_t) (image->columns*image->rows);
2527   if (AcquireImageColormap(image,number_colors) == MagickFalse)
2528     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
2529       image->filename);
2530   i=0;
2531   image_view=AcquireCacheView(image);
2532   for (y=0; y < (ssize_t) image->rows; y++)
2533   {
2534     MagickBooleanType
2535       proceed;
2536
2537     register IndexPacket
2538       *restrict indexes;
2539
2540     register PixelPacket
2541       *restrict q;
2542
2543     register ssize_t
2544       x;
2545
2546     q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
2547     if (q == (const PixelPacket *) NULL)
2548       break;
2549     indexes=GetCacheViewAuthenticIndexQueue(image_view);
2550     for (x=0; x < (ssize_t) image->columns; x++)
2551     {
2552       indexes[x]=(IndexPacket) i;
2553       image->colormap[i++]=(*q++);
2554     }
2555     if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
2556       break;
2557     proceed=SetImageProgress(image,AssignImageTag,(MagickOffsetType) y,
2558       image->rows);
2559     if (proceed == MagickFalse)
2560       status=MagickFalse;
2561   }
2562   image_view=DestroyCacheView(image_view);
2563   return(status);
2564 }
2565
2566 MagickExport MagickBooleanType QuantizeImage(const QuantizeInfo *quantize_info,
2567   Image *image)
2568 {
2569   CubeInfo
2570     *cube_info;
2571
2572   MagickBooleanType
2573     status;
2574
2575   size_t
2576     depth,
2577     maximum_colors;
2578
2579   assert(quantize_info != (const QuantizeInfo *) NULL);
2580   assert(quantize_info->signature == MagickSignature);
2581   assert(image != (Image *) NULL);
2582   assert(image->signature == MagickSignature);
2583   if (image->debug != MagickFalse)
2584     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
2585   maximum_colors=quantize_info->number_colors;
2586   if (maximum_colors == 0)
2587     maximum_colors=MaxColormapSize;
2588   if (maximum_colors > MaxColormapSize)
2589     maximum_colors=MaxColormapSize;
2590   if ((image->columns*image->rows) <= maximum_colors)
2591     return(DirectToColormapImage(image,&image->exception));
2592   if ((IsGrayImage(image,&image->exception) != MagickFalse) &&
2593       (image->matte == MagickFalse))
2594     (void) SetGrayscaleImage(image);
2595   if ((image->storage_class == PseudoClass) &&
2596       (image->colors <= maximum_colors))
2597     return(MagickTrue);
2598   depth=quantize_info->tree_depth;
2599   if (depth == 0)
2600     {
2601       size_t
2602         colors;
2603
2604       /*
2605         Depth of color tree is: Log4(colormap size)+2.
2606       */
2607       colors=maximum_colors;
2608       for (depth=1; colors != 0; depth++)
2609         colors>>=2;
2610       if ((quantize_info->dither != MagickFalse) && (depth > 2))
2611         depth--;
2612       if ((image->matte != MagickFalse) && (depth > 5))
2613         depth--;
2614     }
2615   /*
2616     Initialize color cube.
2617   */
2618   cube_info=GetCubeInfo(quantize_info,depth,maximum_colors);
2619   if (cube_info == (CubeInfo *) NULL)
2620     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
2621       image->filename);
2622   status=ClassifyImageColors(cube_info,image,&image->exception);
2623   if (status != MagickFalse)
2624     {
2625       /*
2626         Reduce the number of colors in the image.
2627       */
2628       ReduceImageColors(image,cube_info);
2629       status=AssignImageColors(image,cube_info);
2630     }
2631   DestroyCubeInfo(cube_info);
2632   return(status);
2633 }
2634 \f
2635 /*
2636 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2637 %                                                                             %
2638 %                                                                             %
2639 %                                                                             %
2640 %   Q u a n t i z e I m a g e s                                               %
2641 %                                                                             %
2642 %                                                                             %
2643 %                                                                             %
2644 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2645 %
2646 %  QuantizeImages() analyzes the colors within a set of reference images and
2647 %  chooses a fixed number of colors to represent the set.  The goal of the
2648 %  algorithm is to minimize the color difference between the input and output
2649 %  images while minimizing the processing time.
2650 %
2651 %  The format of the QuantizeImages method is:
2652 %
2653 %      MagickBooleanType QuantizeImages(const QuantizeInfo *quantize_info,
2654 %        Image *images)
2655 %
2656 %  A description of each parameter follows:
2657 %
2658 %    o quantize_info: Specifies a pointer to an QuantizeInfo structure.
2659 %
2660 %    o images: Specifies a pointer to a list of Image structures.
2661 %
2662 */
2663 MagickExport MagickBooleanType QuantizeImages(const QuantizeInfo *quantize_info,
2664   Image *images)
2665 {
2666   CubeInfo
2667     *cube_info;
2668
2669   Image
2670     *image;
2671
2672   MagickBooleanType
2673     proceed,
2674     status;
2675
2676   MagickProgressMonitor
2677     progress_monitor;
2678
2679   register ssize_t
2680     i;
2681
2682   size_t
2683     depth,
2684     maximum_colors,
2685     number_images;
2686
2687   assert(quantize_info != (const QuantizeInfo *) NULL);
2688   assert(quantize_info->signature == MagickSignature);
2689   assert(images != (Image *) NULL);
2690   assert(images->signature == MagickSignature);
2691   if (images->debug != MagickFalse)
2692     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",images->filename);
2693   if (GetNextImageInList(images) == (Image *) NULL)
2694     {
2695       /*
2696         Handle a single image with QuantizeImage.
2697       */
2698       status=QuantizeImage(quantize_info,images);
2699       return(status);
2700     }
2701   status=MagickFalse;
2702   maximum_colors=quantize_info->number_colors;
2703   if (maximum_colors == 0)
2704     maximum_colors=MaxColormapSize;
2705   if (maximum_colors > MaxColormapSize)
2706     maximum_colors=MaxColormapSize;
2707   depth=quantize_info->tree_depth;
2708   if (depth == 0)
2709     {
2710       size_t
2711         colors;
2712
2713       /*
2714         Depth of color tree is: Log4(colormap size)+2.
2715       */
2716       colors=maximum_colors;
2717       for (depth=1; colors != 0; depth++)
2718         colors>>=2;
2719       if (quantize_info->dither != MagickFalse)
2720         depth--;
2721     }
2722   /*
2723     Initialize color cube.
2724   */
2725   cube_info=GetCubeInfo(quantize_info,depth,maximum_colors);
2726   if (cube_info == (CubeInfo *) NULL)
2727     {
2728       (void) ThrowMagickException(&images->exception,GetMagickModule(),
2729         ResourceLimitError,"MemoryAllocationFailed","`%s'",images->filename);
2730       return(MagickFalse);
2731     }
2732   number_images=GetImageListLength(images);
2733   image=images;
2734   for (i=0; image != (Image *) NULL; i++)
2735   {
2736     progress_monitor=SetImageProgressMonitor(image,(MagickProgressMonitor) NULL,
2737       image->client_data);
2738     status=ClassifyImageColors(cube_info,image,&image->exception);
2739     if (status == MagickFalse)
2740       break;
2741     (void) SetImageProgressMonitor(image,progress_monitor,image->client_data);
2742     proceed=SetImageProgress(image,AssignImageTag,(MagickOffsetType) i,
2743       number_images);
2744     if (proceed == MagickFalse)
2745       break;
2746     image=GetNextImageInList(image);
2747   }
2748   if (status != MagickFalse)
2749     {
2750       /*
2751         Reduce the number of colors in an image sequence.
2752       */
2753       ReduceImageColors(images,cube_info);
2754       image=images;
2755       for (i=0; image != (Image *) NULL; i++)
2756       {
2757         progress_monitor=SetImageProgressMonitor(image,(MagickProgressMonitor)
2758           NULL,image->client_data);
2759         status=AssignImageColors(image,cube_info);
2760         if (status == MagickFalse)
2761           break;
2762         (void) SetImageProgressMonitor(image,progress_monitor,
2763           image->client_data);
2764         proceed=SetImageProgress(image,AssignImageTag,(MagickOffsetType) i,
2765           number_images);
2766         if (proceed == MagickFalse)
2767           break;
2768         image=GetNextImageInList(image);
2769       }
2770     }
2771   DestroyCubeInfo(cube_info);
2772   return(status);
2773 }
2774 \f
2775 /*
2776 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2777 %                                                                             %
2778 %                                                                             %
2779 %                                                                             %
2780 +   R e d u c e                                                               %
2781 %                                                                             %
2782 %                                                                             %
2783 %                                                                             %
2784 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2785 %
2786 %  Reduce() traverses the color cube tree and prunes any node whose
2787 %  quantization error falls below a particular threshold.
2788 %
2789 %  The format of the Reduce method is:
2790 %
2791 %      Reduce(const Image *image,CubeInfo *cube_info,const NodeInfo *node_info)
2792 %
2793 %  A description of each parameter follows.
2794 %
2795 %    o image: the image.
2796 %
2797 %    o cube_info: A pointer to the Cube structure.
2798 %
2799 %    o node_info: pointer to node in color cube tree that is to be pruned.
2800 %
2801 */
2802 static void Reduce(const Image *image,CubeInfo *cube_info,
2803   const NodeInfo *node_info)
2804 {
2805   register ssize_t
2806     i;
2807
2808   size_t
2809     number_children;
2810
2811   /*
2812     Traverse any children.
2813   */
2814   number_children=cube_info->associate_alpha == MagickFalse ? 8UL : 16UL;
2815   for (i=0; i < (ssize_t) number_children; i++)
2816     if (node_info->child[i] != (NodeInfo *) NULL)
2817       Reduce(image,cube_info,node_info->child[i]);
2818   if (node_info->quantize_error <= cube_info->pruning_threshold)
2819     PruneChild(image,cube_info,node_info);
2820   else
2821     {
2822       /*
2823         Find minimum pruning threshold.
2824       */
2825       if (node_info->number_unique > 0)
2826         cube_info->colors++;
2827       if (node_info->quantize_error < cube_info->next_threshold)
2828         cube_info->next_threshold=node_info->quantize_error;
2829     }
2830 }
2831 \f
2832 /*
2833 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2834 %                                                                             %
2835 %                                                                             %
2836 %                                                                             %
2837 +   R e d u c e I m a g e C o l o r s                                         %
2838 %                                                                             %
2839 %                                                                             %
2840 %                                                                             %
2841 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2842 %
2843 %  ReduceImageColors() repeatedly prunes the tree until the number of nodes
2844 %  with n2 > 0 is less than or equal to the maximum number of colors allowed
2845 %  in the output image.  On any given iteration over the tree, it selects
2846 %  those nodes whose E value is minimal for pruning and merges their
2847 %  color statistics upward. It uses a pruning threshold, Ep, to govern
2848 %  node selection as follows:
2849 %
2850 %    Ep = 0
2851 %    while number of nodes with (n2 > 0) > required maximum number of colors
2852 %      prune all nodes such that E <= Ep
2853 %      Set Ep to minimum E in remaining nodes
2854 %
2855 %  This has the effect of minimizing any quantization error when merging
2856 %  two nodes together.
2857 %
2858 %  When a node to be pruned has offspring, the pruning procedure invokes
2859 %  itself recursively in order to prune the tree from the leaves upward.
2860 %  n2,  Sr, Sg,  and  Sb in a node being pruned are always added to the
2861 %  corresponding data in that node's parent.  This retains the pruned
2862 %  node's color characteristics for later averaging.
2863 %
2864 %  For each node, n2 pixels exist for which that node represents the
2865 %  smallest volume in RGB space containing those pixel's colors.  When n2
2866 %  > 0 the node will uniquely define a color in the output image. At the
2867 %  beginning of reduction,  n2 = 0  for all nodes except a the leaves of
2868 %  the tree which represent colors present in the input image.
2869 %
2870 %  The other pixel count, n1, indicates the total number of colors
2871 %  within the cubic volume which the node represents.  This includes n1 -
2872 %  n2  pixels whose colors should be defined by nodes at a lower level in
2873 %  the tree.
2874 %
2875 %  The format of the ReduceImageColors method is:
2876 %
2877 %      ReduceImageColors(const Image *image,CubeInfo *cube_info)
2878 %
2879 %  A description of each parameter follows.
2880 %
2881 %    o image: the image.
2882 %
2883 %    o cube_info: A pointer to the Cube structure.
2884 %
2885 */
2886 static void ReduceImageColors(const Image *image,CubeInfo *cube_info)
2887 {
2888 #define ReduceImageTag  "Reduce/Image"
2889
2890   MagickBooleanType
2891     proceed;
2892
2893   MagickOffsetType
2894     offset;
2895
2896   size_t
2897     span;
2898
2899   cube_info->next_threshold=0.0;
2900   for (span=cube_info->colors; cube_info->colors > cube_info->maximum_colors; )
2901   {
2902     cube_info->pruning_threshold=cube_info->next_threshold;
2903     cube_info->next_threshold=cube_info->root->quantize_error-1;
2904     cube_info->colors=0;
2905     Reduce(image,cube_info,cube_info->root);
2906     offset=(MagickOffsetType) span-cube_info->colors;
2907     proceed=SetImageProgress(image,ReduceImageTag,offset,span-
2908       cube_info->maximum_colors+1);
2909     if (proceed == MagickFalse)
2910       break;
2911   }
2912 }
2913 \f
2914 /*
2915 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2916 %                                                                             %
2917 %                                                                             %
2918 %                                                                             %
2919 %   R e m a p I m a g e                                                       %
2920 %                                                                             %
2921 %                                                                             %
2922 %                                                                             %
2923 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2924 %
2925 %  RemapImage() replaces the colors of an image with the closest color from
2926 %  a reference image.
2927 %
2928 %  The format of the RemapImage method is:
2929 %
2930 %      MagickBooleanType RemapImage(const QuantizeInfo *quantize_info,
2931 %        Image *image,const Image *remap_image)
2932 %
2933 %  A description of each parameter follows:
2934 %
2935 %    o quantize_info: Specifies a pointer to an QuantizeInfo structure.
2936 %
2937 %    o image: the image.
2938 %
2939 %    o remap_image: the reference image.
2940 %
2941 */
2942 MagickExport MagickBooleanType RemapImage(const QuantizeInfo *quantize_info,
2943   Image *image,const Image *remap_image)
2944 {
2945   CubeInfo
2946     *cube_info;
2947
2948   MagickBooleanType
2949     status;
2950
2951   /*
2952     Initialize color cube.
2953   */
2954   assert(image != (Image *) NULL);
2955   assert(image->signature == MagickSignature);
2956   if (image->debug != MagickFalse)
2957     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
2958   assert(remap_image != (Image *) NULL);
2959   assert(remap_image->signature == MagickSignature);
2960   cube_info=GetCubeInfo(quantize_info,MaxTreeDepth,
2961     quantize_info->number_colors);
2962   if (cube_info == (CubeInfo *) NULL)
2963     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
2964       image->filename);
2965   status=ClassifyImageColors(cube_info,remap_image,&image->exception);
2966   if (status != MagickFalse)
2967     {
2968       /*
2969         Classify image colors from the reference image.
2970       */
2971       cube_info->quantize_info->number_colors=cube_info->colors;
2972       status=AssignImageColors(image,cube_info);
2973     }
2974   DestroyCubeInfo(cube_info);
2975   return(status);
2976 }
2977 \f
2978 /*
2979 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2980 %                                                                             %
2981 %                                                                             %
2982 %                                                                             %
2983 %   R e m a p I m a g e s                                                     %
2984 %                                                                             %
2985 %                                                                             %
2986 %                                                                             %
2987 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2988 %
2989 %  RemapImages() replaces the colors of a sequence of images with the
2990 %  closest color from a reference image.
2991 %
2992 %  The format of the RemapImage method is:
2993 %
2994 %      MagickBooleanType RemapImages(const QuantizeInfo *quantize_info,
2995 %        Image *images,Image *remap_image)
2996 %
2997 %  A description of each parameter follows:
2998 %
2999 %    o quantize_info: Specifies a pointer to an QuantizeInfo structure.
3000 %
3001 %    o images: the image sequence.
3002 %
3003 %    o remap_image: the reference image.
3004 %
3005 */
3006 MagickExport MagickBooleanType RemapImages(const QuantizeInfo *quantize_info,
3007   Image *images,const Image *remap_image)
3008 {
3009   CubeInfo
3010     *cube_info;
3011
3012   Image
3013     *image;
3014
3015   MagickBooleanType
3016     status;
3017
3018   assert(images != (Image *) NULL);
3019   assert(images->signature == MagickSignature);
3020   if (images->debug != MagickFalse)
3021     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",images->filename);
3022   image=images;
3023   if (remap_image == (Image *) NULL)
3024     {
3025       /*
3026         Create a global colormap for an image sequence.
3027       */
3028       status=QuantizeImages(quantize_info,images);
3029       return(status);
3030     }
3031   /*
3032     Classify image colors from the reference image.
3033   */
3034   cube_info=GetCubeInfo(quantize_info,MaxTreeDepth,
3035     quantize_info->number_colors);
3036   if (cube_info == (CubeInfo *) NULL)
3037     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
3038       image->filename);
3039   status=ClassifyImageColors(cube_info,remap_image,&image->exception);
3040   if (status != MagickFalse)
3041     {
3042       /*
3043         Classify image colors from the reference image.
3044       */
3045       cube_info->quantize_info->number_colors=cube_info->colors;
3046       image=images;
3047       for ( ; image != (Image *) NULL; image=GetNextImageInList(image))
3048       {
3049         status=AssignImageColors(image,cube_info);
3050         if (status == MagickFalse)
3051           break;
3052       }
3053     }
3054   DestroyCubeInfo(cube_info);
3055   return(status);
3056 }
3057 \f
3058 /*
3059 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3060 %                                                                             %
3061 %                                                                             %
3062 %                                                                             %
3063 %   S e t G r a y s c a l e I m a g e                                         %
3064 %                                                                             %
3065 %                                                                             %
3066 %                                                                             %
3067 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3068 %
3069 %  SetGrayscaleImage() converts an image to a PseudoClass grayscale image.
3070 %
3071 %  The format of the SetGrayscaleImage method is:
3072 %
3073 %      MagickBooleanType SetGrayscaleImage(Image *image)
3074 %
3075 %  A description of each parameter follows:
3076 %
3077 %    o image: The image.
3078 %
3079 */
3080
3081 #if defined(__cplusplus) || defined(c_plusplus)
3082 extern "C" {
3083 #endif
3084
3085 static int IntensityCompare(const void *x,const void *y)
3086 {
3087   PixelPacket
3088     *color_1,
3089     *color_2;
3090
3091   ssize_t
3092     intensity;
3093
3094   color_1=(PixelPacket *) x;
3095   color_2=(PixelPacket *) y;
3096   intensity=PixelIntensityToQuantum(color_1)-(ssize_t)
3097     PixelIntensityToQuantum(color_2);
3098   return((int) intensity);
3099 }
3100
3101 #if defined(__cplusplus) || defined(c_plusplus)
3102 }
3103 #endif
3104
3105 static MagickBooleanType SetGrayscaleImage(Image *image)
3106 {
3107   CacheView
3108     *image_view;
3109
3110   ExceptionInfo
3111     *exception;
3112
3113   MagickBooleanType
3114     status;
3115
3116   PixelPacket
3117     *colormap;
3118
3119   register ssize_t
3120     i;
3121
3122   ssize_t
3123     *colormap_index,
3124     j,
3125     y;
3126
3127   assert(image != (Image *) NULL);
3128   assert(image->signature == MagickSignature);
3129   if (image->type != GrayscaleType)
3130     (void) TransformImageColorspace(image,GRAYColorspace);
3131   colormap_index=(ssize_t *) AcquireQuantumMemory(MaxMap+1,
3132     sizeof(*colormap_index));
3133   if (colormap_index == (ssize_t *) NULL)
3134     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
3135       image->filename);
3136   if (image->storage_class != PseudoClass)
3137     {
3138       ExceptionInfo
3139         *exception;
3140
3141       for (i=0; i <= (ssize_t) MaxMap; i++)
3142         colormap_index[i]=(-1);
3143       if (AcquireImageColormap(image,MaxMap+1) == MagickFalse)
3144         ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
3145           image->filename);
3146       image->colors=0;
3147       status=MagickTrue;
3148       exception=(&image->exception);
3149       image_view=AcquireCacheView(image);
3150 #if defined(MAGICKCORE_OPENMP_SUPPORT)
3151   #pragma omp parallel for schedule(dynamic,4) shared(status)
3152 #endif
3153       for (y=0; y < (ssize_t) image->rows; y++)
3154       {
3155         register IndexPacket
3156           *restrict indexes;
3157
3158         register const PixelPacket
3159           *restrict q;
3160
3161         register ssize_t
3162           x;
3163
3164         if (status == MagickFalse)
3165           continue;
3166         q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,
3167           exception);
3168         if (q == (PixelPacket *) NULL)
3169           {
3170             status=MagickFalse;
3171             continue;
3172           }
3173         indexes=GetCacheViewAuthenticIndexQueue(image_view);
3174         for (x=0; x < (ssize_t) image->columns; x++)
3175         {
3176           register size_t
3177             intensity;
3178
3179           intensity=ScaleQuantumToMap(q->red);
3180           if (colormap_index[intensity] < 0)
3181             {
3182 #if defined(MAGICKCORE_OPENMP_SUPPORT)
3183     #pragma omp critical (MagickCore_SetGrayscaleImage)
3184 #endif
3185               if (colormap_index[intensity] < 0)
3186                 {
3187                   colormap_index[intensity]=(ssize_t) image->colors;
3188                   image->colormap[image->colors]=(*q);
3189                   image->colors++;
3190                }
3191             }
3192           indexes[x]=(IndexPacket) colormap_index[intensity];
3193           q++;
3194         }
3195         if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
3196           status=MagickFalse;
3197       }
3198       image_view=DestroyCacheView(image_view);
3199     }
3200   for (i=0; i < (ssize_t) image->colors; i++)
3201     image->colormap[i].opacity=(unsigned short) i;
3202   qsort((void *) image->colormap,image->colors,sizeof(PixelPacket),
3203     IntensityCompare);
3204   colormap=(PixelPacket *) AcquireQuantumMemory(image->colors,
3205     sizeof(*colormap));
3206   if (colormap == (PixelPacket *) NULL)
3207     ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
3208       image->filename);
3209   j=0;
3210   colormap[j]=image->colormap[0];
3211   for (i=0; i < (ssize_t) image->colors; i++)
3212   {
3213     if (IsSameColor(image,&colormap[j],&image->colormap[i]) == MagickFalse)
3214       {
3215         j++;
3216         colormap[j]=image->colormap[i];
3217       }
3218     colormap_index[(ssize_t) image->colormap[i].opacity]=j;
3219   }
3220   image->colors=(size_t) (j+1);
3221   image->colormap=(PixelPacket *) RelinquishMagickMemory(image->colormap);
3222   image->colormap=colormap;
3223   status=MagickTrue;
3224   exception=(&image->exception);
3225   image_view=AcquireCacheView(image);
3226 #if defined(MAGICKCORE_OPENMP_SUPPORT)
3227   #pragma omp parallel for schedule(dynamic,4) shared(status)
3228 #endif
3229   for (y=0; y < (ssize_t) image->rows; y++)
3230   {
3231     register IndexPacket
3232       *restrict indexes;
3233
3234     register const PixelPacket
3235       *restrict q;
3236
3237     register ssize_t
3238       x;
3239
3240     if (status == MagickFalse)
3241       continue;
3242     q=GetCacheViewAuthenticPixels(image_view,0,y,image->columns,1,exception);
3243     if (q == (PixelPacket *) NULL)
3244       {
3245         status=MagickFalse;
3246         continue;
3247       }
3248     indexes=GetCacheViewAuthenticIndexQueue(image_view);
3249     for (x=0; x < (ssize_t) image->columns; x++)
3250       indexes[x]=(IndexPacket) colormap_index[ScaleQuantumToMap(indexes[x])];
3251     if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
3252       status=MagickFalse;
3253   }
3254   image_view=DestroyCacheView(image_view);
3255   colormap_index=(ssize_t *) RelinquishMagickMemory(colormap_index);
3256   image->type=GrayscaleType;
3257   if (IsMonochromeImage(image,&image->exception) != MagickFalse)
3258     image->type=BilevelType;
3259   return(status);
3260 }