granicus.if.org Git - imagemagick/blob - coders/stegano.c

   1 /*
   2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   3 %                                                                             %
   4 %                                                                             %
   5 %                                                                             %
   6 %              SSSSS  TTTTT  EEEEE   GGGG   AAA   N   N   OOO                 %
   7 %              SS       T    E      G      A   A  NN  N  O   O                %
   8 %               SSS     T    EEE    G  GG  AAAAA  N N N  O   O                %
   9 %                 SS    T    E      G   G  A   A  N  NN  O   O                %
  10 %              SSSSS    T    EEEEE   GGG   A   A  N   N   OOO                 %
  11 %                                                                             %
  12 %                                                                             %
  13 %                       Write A Steganographic 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 %
  37 */
  38 \f
  39 /*
  40   Include declarations.
  41 */
  42 #include "MagickCore/studio.h"
  43 #include "MagickCore/blob.h"
  44 #include "MagickCore/blob-private.h"
  45 #include "MagickCore/cache.h"
  46 #include "MagickCore/colormap.h"
  47 #include "MagickCore/constitute.h"
  48 #include "MagickCore/exception.h"
  49 #include "MagickCore/exception-private.h"
  50 #include "MagickCore/image.h"
  51 #include "MagickCore/image-private.h"
  52 #include "MagickCore/list.h"
  53 #include "MagickCore/magick.h"
  54 #include "MagickCore/memory_.h"
  55 #include "MagickCore/monitor.h"
  56 #include "MagickCore/monitor-private.h"
  57 #include "MagickCore/pixel-accessor.h"
  58 #include "MagickCore/quantum-private.h"
  59 #include "MagickCore/static.h"
  60 #include "MagickCore/string_.h"
  61 #include "MagickCore/module.h"
  62 \f
  63 /*
  64 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  65 %                                                                             %
  66 %                                                                             %
  67 %                                                                             %
  68 %   R e a d S T E G A N O I m a g e                                           %
  69 %                                                                             %
  70 %                                                                             %
  71 %                                                                             %
  72 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  73 %
  74 %  ReadSTEGANOImage() reads a steganographic image hidden within another
  75 %  image type.  It allocates the memory necessary for the new Image structure
  76 %  and returns a pointer to the new image.
  77 %
  78 %  The format of the ReadSTEGANOImage method is:
  79 %
  80 %      Image *ReadSTEGANOImage(const ImageInfo *image_info,
  81 %        ExceptionInfo *exception)
  82 %
  83 %  A description of each parameter follows:
  84 %
  85 %    o image_info: the image info.
  86 %
  87 %    o exception: return any errors or warnings in this structure.
  88 %
  89 */
  90
  91 static inline size_t MagickMin(const size_t x,
  92   const size_t y)
  93 {
  94   if (x < y)
  95     return(x);
  96   return(y);
  97 }
  98
  99 static Image *ReadSTEGANOImage(const ImageInfo *image_info,
 100   ExceptionInfo *exception)
 101 {
 102 #define GetBit(alpha,i) MagickMin((((size_t) (alpha) >> (size_t) \
 103   (i)) & 0x01),16)
 104 #define SetBit(i,set) SetPixelIndex(image,((set) != 0 ? \
 105   (size_t) GetPixelIndex(image,q) | (one << (size_t) (i)) : \
 106   (size_t) GetPixelIndex(image,q) & ~(one << (size_t) (i))),q)
 107
 108   Image
 109     *image,
 110     *watermark;
 111
 112   ImageInfo
 113     *read_info;
 114
 115   int
 116     c;
 117
 118   MagickBooleanType
 119     status;
 120
 121   PixelPacket
 122     pixel;
 123
 124   register Quantum
 125     *q;
 126
 127   register ssize_t
 128     x;
 129
 130   size_t
 131     depth,
 132     one;
 133
 134   ssize_t
 135     i,
 136     j,
 137     k,
 138     y;
 139
 140   /*
 141     Initialize Image structure.
 142   */
 143   assert(image_info != (const ImageInfo *) NULL);
 144   assert(image_info->signature == MagickSignature);
 145   if (image_info->debug != MagickFalse)
 146     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
 147       image_info->filename);
 148   assert(exception != (ExceptionInfo *) NULL);
 149   assert(exception->signature == MagickSignature);
 150   one=1;
 151   image=AcquireImage(image_info,exception);
 152   if ((image->columns == 0) || (image->rows == 0))
 153     ThrowReaderException(OptionError,"MustSpecifyImageSize");
 154   read_info=CloneImageInfo(image_info);
 155   SetImageInfoBlob(read_info,(void *) NULL,0);
 156   *read_info->magick='\0';
 157   watermark=ReadImage(read_info,exception);
 158   read_info=DestroyImageInfo(read_info);
 159   if (watermark == (Image *) NULL)
 160     return((Image *) NULL);
 161   watermark->depth=MAGICKCORE_QUANTUM_DEPTH;
 162   if (AcquireImageColormap(image,MaxColormapSize,exception) == MagickFalse)
 163     ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
 164   if (image_info->ping != MagickFalse)
 165     {
 166       (void) CloseBlob(image);
 167       return(GetFirstImageInList(image));
 168     }
 169   /*
 170     Get hidden watermark from low-order bits of image.
 171   */
 172   c=0;
 173   i=0;
 174   j=0;
 175   i=(ssize_t) (watermark->depth-1);
 176   depth=watermark->depth;
 177   for (k=image->offset; (i >= 0) && (j < (ssize_t) depth); i--)
 178   {
 179     for (y=0; (y < (ssize_t) image->rows) && (j < (ssize_t) depth); y++)
 180     {
 181       x=0;
 182       for ( ; (x < (ssize_t) image->columns) && (j < (ssize_t) depth); x++)
 183       {
 184         Quantum
 185           virtual_pixel[MaxPixelChannels];
 186
 187         if ((k/(ssize_t) watermark->columns) >= (ssize_t) watermark->rows)
 188           break;
 189         (void) GetOneVirtualPixel(watermark,k % (ssize_t) watermark->columns,
 190           k/(ssize_t) watermark->columns,virtual_pixel,exception);
 191         pixel.red=virtual_pixel[RedPixelChannel];
 192         pixel.green=virtual_pixel[GreenPixelChannel];
 193         pixel.blue=virtual_pixel[BluePixelChannel];
 194         pixel.alpha=virtual_pixel[AlphaPixelChannel];
 195         q=GetAuthenticPixels(image,x,y,1,1,exception);
 196         if (q == (Quantum *) NULL)
 197           break;
 198         switch (c)
 199         {
 200           case 0:
 201           {
 202             SetBit(i,GetBit(pixel.red,j));
 203             break;
 204           }
 205           case 1:
 206           {
 207             SetBit(i,GetBit(pixel.green,j));
 208             break;
 209           }
 210           case 2:
 211           {
 212             SetBit(i,GetBit(pixel.blue,j));
 213             break;
 214           }
 215         }
 216         if (SyncAuthenticPixels(image,exception) == MagickFalse)
 217           break;
 218         c++;
 219         if (c == 3)
 220           c=0;
 221         k++;
 222         if (k == (ssize_t) (watermark->columns*watermark->columns))
 223           k=0;
 224         if (k == image->offset)
 225           j++;
 226       }
 227     }
 228     status=SetImageProgress(image,LoadImagesTag,(MagickOffsetType) i,depth);
 229     if (status == MagickFalse)
 230       break;
 231   }
 232   watermark=DestroyImage(watermark);
 233   (void) SyncImage(image);
 234   return(GetFirstImageInList(image));
 235 }
 236 \f
 237 /*
 238 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 239 %                                                                             %
 240 %                                                                             %
 241 %                                                                             %
 242 %   R e g i s t e r S T E G A N O I m a g e                                   %
 243 %                                                                             %
 244 %                                                                             %
 245 %                                                                             %
 246 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 247 %
 248 %  RegisterSTEGANOImage() adds attributes for the STEGANO image format to
 249 %  the list of supported formats.  The attributes include the image format
 250 %  tag, a method to read and/or write the format, whether the format
 251 %  supports the saving of more than one frame to the same file or blob,
 252 %  whether the format supports native in-memory I/O, and a brief
 253 %  description of the format.
 254 %
 255 %  The format of the RegisterSTEGANOImage method is:
 256 %
 257 %      size_t RegisterSTEGANOImage(void)
 258 %
 259 */
 260 ModuleExport size_t RegisterSTEGANOImage(void)
 261 {
 262   MagickInfo
 263     *entry;
 264
 265   entry=SetMagickInfo("STEGANO");
 266   entry->decoder=(DecodeImageHandler *) ReadSTEGANOImage;
 267   entry->format_type=ImplicitFormatType;
 268   entry->description=ConstantString("Steganographic image");
 269   entry->module=ConstantString("STEGANO");
 270   (void) RegisterMagickInfo(entry);
 271   return(MagickImageCoderSignature);
 272 }
 273 \f
 274 /*
 275 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 276 %                                                                             %
 277 %                                                                             %
 278 %                                                                             %
 279 %   U n r e g i s t e r S T E G A N O I m a g e                               %
 280 %                                                                             %
 281 %                                                                             %
 282 %                                                                             %
 283 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 284 %
 285 %  UnregisterSTEGANOImage() removes format registrations made by the
 286 %  STEGANO module from the list of supported formats.
 287 %
 288 %  The format of the UnregisterSTEGANOImage method is:
 289 %
 290 %      UnregisterSTEGANOImage(void)
 291 %
 292 */
 293 ModuleExport void UnregisterSTEGANOImage(void)
 294 {
 295   (void) UnregisterMagickInfo("STEGANO");
 296 }