]> granicus.if.org Git - imagemagick/blobdiff - MagickCore/feature.c
Update web pages
[imagemagick] / MagickCore / feature.c
index 01e52f148f904125230397fa5b44e0567c86d3f5..4f5b23700ff17c2576f867290122dd673030220e 100644 (file)
@@ -17,7 +17,7 @@
 %                                 July 1992                                   %
 %                                                                             %
 %                                                                             %
-%  Copyright 1999-2014 ImageMagick Studio LLC, a non-profit organization      %
+%  Copyright 1999-2015 ImageMagick Studio LLC, a non-profit organization      %
 %  dedicated to making software imaging solutions freely available.           %
 %                                                                             %
 %  You may not use this file except in compliance with the License.  You may  %
   Include declarations.
 */
 #include "MagickCore/studio.h"
-#include "MagickCore/property.h"
 #include "MagickCore/animate.h"
+#include "MagickCore/artifact.h"
 #include "MagickCore/blob.h"
 #include "MagickCore/blob-private.h"
 #include "MagickCore/cache.h"
 #include "MagickCore/cache-private.h"
 #include "MagickCore/cache-view.h"
+#include "MagickCore/channel.h"
 #include "MagickCore/client.h"
 #include "MagickCore/color.h"
 #include "MagickCore/color-private.h"
 #include "MagickCore/image-private.h"
 #include "MagickCore/magic.h"
 #include "MagickCore/magick.h"
+#include "MagickCore/matrix.h"
 #include "MagickCore/memory_.h"
 #include "MagickCore/module.h"
 #include "MagickCore/monitor.h"
 #include "MagickCore/monitor-private.h"
+#include "MagickCore/morphology-private.h"
 #include "MagickCore/option.h"
 #include "MagickCore/paint.h"
 #include "MagickCore/pixel-accessor.h"
 #include "MagickCore/profile.h"
+#include "MagickCore/property.h"
 #include "MagickCore/quantize.h"
 #include "MagickCore/quantum-private.h"
 #include "MagickCore/random_.h"
 %                                                                             %
 %                                                                             %
 %                                                                             %
+%     C a n n y E d g e I m a g e                                             %
+%                                                                             %
+%                                                                             %
+%                                                                             %
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%  CannyEdgeImage() uses a multi-stage algorithm to detect a wide range of
+%  edges in images.
+%
+%  The format of the CannyEdgeImage method is:
+%
+%      Image *CannyEdgeImage(const Image *image,const double radius,
+%        const double sigma,const double lower_percent,
+%        const double upper_percent,ExceptionInfo *exception)
+%
+%  A description of each parameter follows:
+%
+%    o image: the image.
+%
+%    o radius: the radius of the gaussian smoothing filter.
+%
+%    o sigma: the sigma of the gaussian smoothing filter.
+%
+%    o lower_precent: percentage of edge pixels in the lower threshold.
+%
+%    o upper_percent: percentage of edge pixels in the upper threshold.
+%
+%    o exception: return any errors or warnings in this structure.
+%
+*/
+
+typedef struct _CannyInfo
+{
+  double
+    magnitude,
+    intensity;
+
+  int
+    orientation;
+
+  ssize_t
+    x,
+    y;
+} CannyInfo;
+
+static inline MagickBooleanType IsAuthenticPixel(const Image *image,
+  const ssize_t x,const ssize_t y)
+{
+  if ((x < 0) || (x >= (ssize_t) image->columns))
+    return(MagickFalse);
+  if ((y < 0) || (y >= (ssize_t) image->rows))
+    return(MagickFalse);
+  return(MagickTrue);
+}
+
+static MagickBooleanType TraceEdges(Image *edge_image,CacheView *edge_view,
+  MatrixInfo *canny_cache,const ssize_t x,const ssize_t y,
+  const double lower_threshold,ExceptionInfo *exception)
+{
+  CannyInfo
+    edge,
+    pixel;
+
+  MagickBooleanType
+    status;
+
+  register Quantum
+    *q;
+
+  register ssize_t
+    i;
+
+  q=GetCacheViewAuthenticPixels(edge_view,x,y,1,1,exception);
+  if (q == (Quantum *) NULL)
+    return(MagickFalse);
+  *q=QuantumRange;
+  status=SyncCacheViewAuthenticPixels(edge_view,exception);
+  if (status == MagickFalse)
+    return(MagickFalse);;
+  if (GetMatrixElement(canny_cache,0,0,&edge) == MagickFalse)
+    return(MagickFalse);
+  edge.x=x;
+  edge.y=y;
+  if (SetMatrixElement(canny_cache,0,0,&edge) == MagickFalse)
+    return(MagickFalse);
+  for (i=1; i != 0; )
+  {
+    ssize_t
+      v;
+
+    i--;
+    status=GetMatrixElement(canny_cache,i,0,&edge);
+    if (status == MagickFalse)
+      return(MagickFalse);
+    for (v=(-1); v <= 1; v++)
+    {
+      ssize_t
+        u;
+
+      for (u=(-1); u <= 1; u++)
+      {
+        if ((u == 0) && (v == 0))
+          continue;
+        if (IsAuthenticPixel(edge_image,edge.x+u,edge.y+v) == MagickFalse)
+          continue;
+        /*
+          Not an edge if gradient value is below the lower threshold.
+        */
+        q=GetCacheViewAuthenticPixels(edge_view,edge.x+u,edge.y+v,1,1,
+          exception);
+        if (q == (Quantum *) NULL)
+          return(MagickFalse);
+        status=GetMatrixElement(canny_cache,edge.x+u,edge.y+v,&pixel);
+        if (status == MagickFalse)
+          return(MagickFalse);
+        if ((GetPixelIntensity(edge_image,q) == 0.0) &&
+            (pixel.intensity >= lower_threshold))
+          {
+            *q=QuantumRange;
+            status=SyncCacheViewAuthenticPixels(edge_view,exception);
+            if (status == MagickFalse)
+              return(MagickFalse);
+            edge.x+=u;
+            edge.y+=v;
+            status=SetMatrixElement(canny_cache,i,0,&edge);
+            if (status == MagickFalse)
+              return(MagickFalse);
+            i++;
+          }
+      }
+    }
+  }
+  return(MagickTrue);
+}
+
+MagickExport Image *CannyEdgeImage(const Image *image,const double radius,
+  const double sigma,const double lower_percent,const double upper_percent,
+  ExceptionInfo *exception)
+{
+#define CannyEdgeImageTag  "CannyEdge/Image"
+
+  CacheView
+    *edge_view;
+
+  CannyInfo
+    pixel;
+
+  char
+    geometry[MagickPathExtent];
+
+  double
+    lower_threshold,
+    max,
+    min,
+    upper_threshold;
+
+  Image
+    *edge_image;
+
+  KernelInfo
+    *kernel_info;
+
+  MagickBooleanType
+    status;
+
+  MagickOffsetType
+    progress;
+
+  MatrixInfo
+    *canny_cache;
+
+  ssize_t
+    y;
+
+  assert(image != (const Image *) NULL);
+  assert(image->signature == MagickCoreSignature);
+  if (image->debug != MagickFalse)
+    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
+  assert(exception != (ExceptionInfo *) NULL);
+  assert(exception->signature == MagickCoreSignature);
+  /*
+    Filter out noise.
+  */
+  (void) FormatLocaleString(geometry,MagickPathExtent,
+    "blur:%.20gx%.20g;blur:%.20gx%.20g+90",radius,sigma,radius,sigma);
+  kernel_info=AcquireKernelInfo(geometry,exception);
+  if (kernel_info == (KernelInfo *) NULL)
+    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
+  edge_image=MorphologyApply(image,ConvolveMorphology,1,kernel_info,
+    UndefinedCompositeOp,0.0,exception);
+  kernel_info=DestroyKernelInfo(kernel_info);
+  if (edge_image == (Image *) NULL)
+    return((Image *) NULL);
+  if (SetImageColorspace(edge_image,GRAYColorspace,exception) == MagickFalse)
+    {
+      edge_image=DestroyImage(edge_image);
+      return((Image *) NULL);
+    }
+  (void) SetImageAlphaChannel(edge_image,OffAlphaChannel,exception);
+  /*
+    Find the intensity gradient of the image.
+  */
+  canny_cache=AcquireMatrixInfo(edge_image->columns,edge_image->rows,
+    sizeof(CannyInfo),exception);
+  if (canny_cache == (MatrixInfo *) NULL)
+    {
+      edge_image=DestroyImage(edge_image);
+      return((Image *) NULL);
+    }
+  status=MagickTrue;
+  edge_view=AcquireVirtualCacheView(edge_image,exception);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+  #pragma omp parallel for schedule(static,4) shared(status) \
+    magick_threads(edge_image,edge_image,edge_image->rows,1)
+#endif
+  for (y=0; y < (ssize_t) edge_image->rows; y++)
+  {
+    register const Quantum
+      *restrict p;
+
+    register ssize_t
+      x;
+
+    if (status == MagickFalse)
+      continue;
+    p=GetCacheViewVirtualPixels(edge_view,0,y,edge_image->columns+1,2,
+      exception);
+    if (p == (const Quantum *) NULL)
+      {
+        status=MagickFalse;
+        continue;
+      }
+    for (x=0; x < (ssize_t) edge_image->columns; x++)
+    {
+      CannyInfo
+        pixel;
+
+      double
+        dx,
+        dy;
+
+      register const Quantum
+        *restrict kernel_pixels;
+
+      ssize_t
+        v;
+
+      static double
+        Gx[2][2] =
+        {
+          { -1.0,  +1.0 },
+          { -1.0,  +1.0 }
+        },
+        Gy[2][2] =
+        {
+          { +1.0, +1.0 },
+          { -1.0, -1.0 }
+        };
+
+      (void) ResetMagickMemory(&pixel,0,sizeof(pixel));
+      dx=0.0;
+      dy=0.0;
+      kernel_pixels=p;
+      for (v=0; v < 2; v++)
+      {
+        ssize_t
+          u;
+
+        for (u=0; u < 2; u++)
+        {
+          double
+            intensity;
+
+          intensity=GetPixelIntensity(edge_image,kernel_pixels+u);
+          dx+=0.5*Gx[v][u]*intensity;
+          dy+=0.5*Gy[v][u]*intensity;
+        }
+        kernel_pixels+=edge_image->columns+1;
+      }
+      pixel.magnitude=hypot(dx,dy);
+      pixel.orientation=0;
+      if (fabs(dx) > MagickEpsilon)
+        {
+          double
+            slope;
+
+          slope=dy/dx;
+          if (slope < 0.0)
+            {
+              if (slope < -2.41421356237)
+                pixel.orientation=0;
+              else
+                if (slope < -0.414213562373)
+                  pixel.orientation=1;
+                else
+                  pixel.orientation=2;
+            }
+          else
+            {
+              if (slope > 2.41421356237)
+                pixel.orientation=0;
+              else
+                if (slope > 0.414213562373)
+                  pixel.orientation=3;
+                else
+                  pixel.orientation=2;
+            }
+        }
+      if (SetMatrixElement(canny_cache,x,y,&pixel) == MagickFalse)
+        continue;
+      p+=GetPixelChannels(edge_image);
+    }
+  }
+  edge_view=DestroyCacheView(edge_view);
+  /*
+    Non-maxima suppression, remove pixels that are not considered to be part
+    of an edge.
+  */
+  progress=0;
+  (void) GetMatrixElement(canny_cache,0,0,&pixel);
+  max=pixel.intensity;
+  min=pixel.intensity;
+  edge_view=AcquireAuthenticCacheView(edge_image,exception);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+  #pragma omp parallel for schedule(static,4) shared(status) \
+    magick_threads(edge_image,edge_image,edge_image->rows,1)
+#endif
+  for (y=0; y < (ssize_t) edge_image->rows; y++)
+  {
+    register Quantum
+      *restrict q;
+
+    register ssize_t
+      x;
+
+    if (status == MagickFalse)
+      continue;
+    q=GetCacheViewAuthenticPixels(edge_view,0,y,edge_image->columns,1,
+      exception);
+    if (q == (Quantum *) NULL)
+      {
+        status=MagickFalse;
+        continue;
+      }
+    for (x=0; x < (ssize_t) edge_image->columns; x++)
+    {
+      CannyInfo
+        alpha_pixel,
+        beta_pixel,
+        pixel;
+
+      (void) GetMatrixElement(canny_cache,x,y,&pixel);
+      switch (pixel.orientation)
+      {
+        case 0:
+        default:
+        {
+          /*
+            0 degrees, north and south.
+          */
+          (void) GetMatrixElement(canny_cache,x,y-1,&alpha_pixel);
+          (void) GetMatrixElement(canny_cache,x,y+1,&beta_pixel);
+          break;
+        }
+        case 1:
+        {
+          /*
+            45 degrees, northwest and southeast.
+          */
+          (void) GetMatrixElement(canny_cache,x-1,y-1,&alpha_pixel);
+          (void) GetMatrixElement(canny_cache,x+1,y+1,&beta_pixel);
+          break;
+        }
+        case 2:
+        {
+          /*
+            90 degrees, east and west.
+          */
+          (void) GetMatrixElement(canny_cache,x-1,y,&alpha_pixel);
+          (void) GetMatrixElement(canny_cache,x+1,y,&beta_pixel);
+          break;
+        }
+        case 3:
+        {
+          /*
+            135 degrees, northeast and southwest.
+          */
+          (void) GetMatrixElement(canny_cache,x+1,y-1,&beta_pixel);
+          (void) GetMatrixElement(canny_cache,x-1,y+1,&alpha_pixel);
+          break;
+        }
+      }
+      pixel.intensity=pixel.magnitude;
+      if ((pixel.magnitude < alpha_pixel.magnitude) ||
+          (pixel.magnitude < beta_pixel.magnitude))
+        pixel.intensity=0;
+      (void) SetMatrixElement(canny_cache,x,y,&pixel);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+      #pragma omp critical (MagickCore_CannyEdgeImage)
+#endif
+      {
+        if (pixel.intensity < min)
+          min=pixel.intensity;
+        if (pixel.intensity > max)
+          max=pixel.intensity;
+      }
+      *q=0;
+      q+=GetPixelChannels(edge_image);
+    }
+    if (SyncCacheViewAuthenticPixels(edge_view,exception) == MagickFalse)
+      status=MagickFalse;
+  }
+  edge_view=DestroyCacheView(edge_view);
+  /*
+    Estimate hysteresis threshold.
+  */
+  lower_threshold=lower_percent*(max-min)+min;
+  upper_threshold=upper_percent*(max-min)+min;
+  /*
+    Hysteresis threshold.
+  */
+  edge_view=AcquireAuthenticCacheView(edge_image,exception);
+  for (y=0; y < (ssize_t) edge_image->rows; y++)
+  {
+    register ssize_t
+      x;
+
+    if (status == MagickFalse)
+      continue;
+    for (x=0; x < (ssize_t) edge_image->columns; x++)
+    {
+      CannyInfo
+        pixel;
+
+      register const Quantum
+        *restrict p;
+
+      /*
+        Edge if pixel gradient higher than upper threshold.
+      */
+      p=GetCacheViewVirtualPixels(edge_view,x,y,1,1,exception);
+      if (p == (const Quantum *) NULL)
+        continue;
+      status=GetMatrixElement(canny_cache,x,y,&pixel);
+      if (status == MagickFalse)
+        continue;
+      if ((GetPixelIntensity(edge_image,p) == 0.0) &&
+          (pixel.intensity >= upper_threshold))
+        status=TraceEdges(edge_image,edge_view,canny_cache,x,y,lower_threshold,
+          exception);
+    }
+    if (image->progress_monitor != (MagickProgressMonitor) NULL)
+      {
+        MagickBooleanType
+          proceed;
+
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+        #pragma omp critical (MagickCore_CannyEdgeImage)
+#endif
+        proceed=SetImageProgress(image,CannyEdgeImageTag,progress++,
+          image->rows);
+        if (proceed == MagickFalse)
+          status=MagickFalse;
+      }
+  }
+  edge_view=DestroyCacheView(edge_view);
+  /*
+    Free resources.
+  */
+  canny_cache=DestroyMatrixInfo(canny_cache);
+  return(edge_image);
+}
+\f
+/*
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%                                                                             %
+%                                                                             %
+%                                                                             %
 %   G e t I m a g e F e a t u r e s                                           %
 %                                                                             %
 %                                                                             %
 %
 */
 
-static inline ssize_t MagickAbsoluteValue(const ssize_t x)
-{
-  if (x < 0)
-    return(-x);
-  return(x);
-}
-
 static inline double MagickLog10(const double x)
 {
-#define Log10Epsilon  (1.0e-26)
+#define Log10Epsilon  (1.0e-11)
 
- return(log10(fabs(x)+Log10Epsilon));
+ if (fabs(x) < Log10Epsilon)
+   return(log10(Log10Epsilon));
+ return(log10(fabs(x)));
 }
 
 MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
@@ -195,7 +672,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
     number_grays;
 
   assert(image != (Image *) NULL);
-  assert(image->signature == MagickSignature);
+  assert(image->signature == MagickCoreSignature);
   if (image->debug != MagickFalse)
     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
   if ((image->columns < (distance+1)) || (image->rows < (distance+1)))
@@ -260,7 +737,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       if (image->colorspace == CMYKColorspace)
         grays[ScaleQuantumToMap(GetPixelBlack(image,p))].black=
           ScaleQuantumToMap(GetPixelBlack(image,p));
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         grays[ScaleQuantumToMap(GetPixelAlpha(image,p))].alpha=
           ScaleQuantumToMap(GetPixelAlpha(image,p));
       p+=GetPixelChannels(image);
@@ -286,7 +763,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
     if (image->colorspace == CMYKColorspace)
       if (grays[i].black != ~0U)
         grays[gray.black++].black=grays[i].black;
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       if (grays[i].alpha != ~0U)
         grays[gray.alpha++].alpha=grays[i].alpha;
   }
@@ -301,7 +778,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
   if (image->colorspace == CMYKColorspace)
     if (gray.black > number_grays)
       number_grays=gray.black;
-  if (image->alpha_trait == BlendPixelTrait)
+  if (image->alpha_trait != UndefinedPixelTrait)
     if (gray.alpha > number_grays)
       number_grays=gray.alpha;
   cooccurrence=(ChannelStatistics **) AcquireQuantumMemory(number_grays,
@@ -503,7 +980,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
             cooccurrence[u][v].direction[i].black++;
             cooccurrence[v][u].direction[i].black++;
           }
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           {
             u=0;
             v=0;
@@ -592,7 +1069,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         cooccurrence[x][y].direction[i].blue*=normalize;
         if (image->colorspace == CMYKColorspace)
           cooccurrence[x][y].direction[i].black*=normalize;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           cooccurrence[x][y].direction[i].alpha*=normalize;
       }
     }
@@ -632,7 +1109,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
           channel_features[BlackPixelChannel].angular_second_moment[i]+=
             cooccurrence[x][y].direction[i].black*
             cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           channel_features[AlphaPixelChannel].angular_second_moment[i]+=
             cooccurrence[x][y].direction[i].alpha*
             cooccurrence[x][y].direction[i].alpha;
@@ -644,7 +1121,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         sum[y].direction[i].blue+=cooccurrence[x][y].direction[i].blue;
         if (image->colorspace == CMYKColorspace)
           sum[y].direction[i].black+=cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           sum[y].direction[i].alpha+=cooccurrence[x][y].direction[i].alpha;
         correlation.direction[i].red+=x*y*cooccurrence[x][y].direction[i].red;
         correlation.direction[i].green+=x*y*
@@ -654,7 +1131,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           correlation.direction[i].black+=x*y*
             cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           correlation.direction[i].alpha+=x*y*
             cooccurrence[x][y].direction[i].alpha;
         /*
@@ -669,7 +1146,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           channel_features[BlackPixelChannel].inverse_difference_moment[i]+=
             cooccurrence[x][y].direction[i].black/((y-x)*(y-x)+1);
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           channel_features[AlphaPixelChannel].inverse_difference_moment[i]+=
             cooccurrence[x][y].direction[i].alpha/((y-x)*(y-x)+1);
         /*
@@ -684,7 +1161,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           density_xy[y+x+2].direction[i].black+=
             cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           density_xy[y+x+2].direction[i].alpha+=
             cooccurrence[x][y].direction[i].alpha;
         /*
@@ -703,7 +1180,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
           channel_features[BlackPixelChannel].entropy[i]-=
             cooccurrence[x][y].direction[i].black*
             MagickLog10(cooccurrence[x][y].direction[i].black);
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           channel_features[AlphaPixelChannel].entropy[i]-=
             cooccurrence[x][y].direction[i].alpha*
             MagickLog10(cooccurrence[x][y].direction[i].alpha);
@@ -713,7 +1190,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         density_x[x].direction[i].red+=cooccurrence[x][y].direction[i].red;
         density_x[x].direction[i].green+=cooccurrence[x][y].direction[i].green;
         density_x[x].direction[i].blue+=cooccurrence[x][y].direction[i].blue;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           density_x[x].direction[i].alpha+=
             cooccurrence[x][y].direction[i].alpha;
         if (image->colorspace == CMYKColorspace)
@@ -725,7 +1202,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           density_y[y].direction[i].black+=
             cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           density_y[y].direction[i].alpha+=
             cooccurrence[x][y].direction[i].alpha;
       }
@@ -740,7 +1217,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
           mean.direction[i].black+=y*sum[y].direction[i].black;
           sum_squares.direction[i].black+=y*y*sum[y].direction[i].black;
         }
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         {
           mean.direction[i].alpha+=y*sum[y].direction[i].alpha;
           sum_squares.direction[i].alpha+=y*y*sum[y].direction[i].alpha;
@@ -774,7 +1251,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         (mean.direction[i].black*mean.direction[i].black))*sqrt(
         sum_squares.direction[i].black-(mean.direction[i].black*
         mean.direction[i].black)));
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       channel_features[AlphaPixelChannel].correlation[i]=
         (correlation.direction[i].alpha-mean.direction[i].alpha*
         mean.direction[i].alpha)/(sqrt(sum_squares.direction[i].alpha-
@@ -808,7 +1285,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       if (image->colorspace == CMYKColorspace)
         channel_features[BlackPixelChannel].sum_average[i]+=
           x*density_xy[x].direction[i].black;
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         channel_features[AlphaPixelChannel].sum_average[i]+=
           x*density_xy[x].direction[i].alpha;
       /*
@@ -827,7 +1304,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         channel_features[BlackPixelChannel].sum_entropy[i]-=
           density_xy[x].direction[i].black*
           MagickLog10(density_xy[x].direction[i].black);
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         channel_features[AlphaPixelChannel].sum_entropy[i]-=
           density_xy[x].direction[i].alpha*
           MagickLog10(density_xy[x].direction[i].alpha);
@@ -851,7 +1328,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
           (x-channel_features[BlackPixelChannel].sum_entropy[i])*
           (x-channel_features[BlackPixelChannel].sum_entropy[i])*
           density_xy[x].direction[i].black;
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         channel_features[AlphaPixelChannel].sum_variance[i]+=
           (x-channel_features[AlphaPixelChannel].sum_entropy[i])*
           (x-channel_features[AlphaPixelChannel].sum_entropy[i])*
@@ -889,7 +1366,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           variance.direction[i].black+=(y-mean.direction[i].black+1)*
             (y-mean.direction[i].black+1)*cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           variance.direction[i].alpha+=(y-mean.direction[i].alpha+1)*
             (y-mean.direction[i].alpha+1)*
             cooccurrence[x][y].direction[i].alpha;
@@ -905,7 +1382,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           density_xy[MagickAbsoluteValue(y-x)].direction[i].black+=
             cooccurrence[x][y].direction[i].black;
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           density_xy[MagickAbsoluteValue(y-x)].direction[i].alpha+=
             cooccurrence[x][y].direction[i].alpha;
         /*
@@ -920,7 +1397,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         if (image->colorspace == CMYKColorspace)
           entropy_xy.direction[i].black-=cooccurrence[x][y].direction[i].black*
             MagickLog10(cooccurrence[x][y].direction[i].black);
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           entropy_xy.direction[i].alpha-=
             cooccurrence[x][y].direction[i].alpha*MagickLog10(
             cooccurrence[x][y].direction[i].alpha);
@@ -935,7 +1412,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
           entropy_xy1.direction[i].black-=(
             cooccurrence[x][y].direction[i].black*MagickLog10(
             density_x[x].direction[i].black*density_y[y].direction[i].black));
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           entropy_xy1.direction[i].alpha-=(
             cooccurrence[x][y].direction[i].alpha*MagickLog10(
             density_x[x].direction[i].alpha*density_y[y].direction[i].alpha));
@@ -952,7 +1429,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
           entropy_xy2.direction[i].black-=(density_x[x].direction[i].black*
             density_y[y].direction[i].black*MagickLog10(
             density_x[x].direction[i].black*density_y[y].direction[i].black));
-        if (image->alpha_trait == BlendPixelTrait)
+        if (image->alpha_trait != UndefinedPixelTrait)
           entropy_xy2.direction[i].alpha-=(density_x[x].direction[i].alpha*
             density_y[y].direction[i].alpha*MagickLog10(
             density_x[x].direction[i].alpha*density_y[y].direction[i].alpha));
@@ -967,7 +1444,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
     if (image->colorspace == CMYKColorspace)
       channel_features[BlackPixelChannel].variance_sum_of_squares[i]=
         variance.direction[i].black;
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       channel_features[AlphaPixelChannel].variance_sum_of_squares[i]=
         variance.direction[i].alpha;
   }
@@ -995,7 +1472,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       variance.direction[i].blue+=density_xy[x].direction[i].blue;
       if (image->colorspace == CMYKColorspace)
         variance.direction[i].black+=density_xy[x].direction[i].black;
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         variance.direction[i].alpha+=density_xy[x].direction[i].alpha;
       sum_squares.direction[i].red+=density_xy[x].direction[i].red*
         density_xy[x].direction[i].red;
@@ -1006,7 +1483,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       if (image->colorspace == CMYKColorspace)
         sum_squares.direction[i].black+=density_xy[x].direction[i].black*
           density_xy[x].direction[i].black;
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         sum_squares.direction[i].alpha+=density_xy[x].direction[i].alpha*
           density_xy[x].direction[i].alpha;
       /*
@@ -1025,7 +1502,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         channel_features[BlackPixelChannel].difference_entropy[i]-=
           density_xy[x].direction[i].black*
           MagickLog10(density_xy[x].direction[i].black);
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         channel_features[AlphaPixelChannel].difference_entropy[i]-=
           density_xy[x].direction[i].alpha*
           MagickLog10(density_xy[x].direction[i].alpha);
@@ -1041,7 +1518,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       if (image->colorspace == CMYKColorspace)
         entropy_x.direction[i].black-=(density_x[x].direction[i].black*
           MagickLog10(density_x[x].direction[i].black));
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         entropy_x.direction[i].alpha-=(density_x[x].direction[i].alpha*
           MagickLog10(density_x[x].direction[i].alpha));
       entropy_y.direction[i].red-=(density_y[x].direction[i].red*
@@ -1053,7 +1530,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       if (image->colorspace == CMYKColorspace)
         entropy_y.direction[i].black-=(density_y[x].direction[i].black*
           MagickLog10(density_y[x].direction[i].black));
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         entropy_y.direction[i].alpha-=(density_y[x].direction[i].alpha*
           MagickLog10(density_y[x].direction[i].alpha));
     }
@@ -1077,7 +1554,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         (((double) number_grays*number_grays*sum_squares.direction[i].black)-
         (variance.direction[i].black*variance.direction[i].black))/
         ((double) number_grays*number_grays*number_grays*number_grays);
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       channel_features[AlphaPixelChannel].difference_variance[i]=
         (((double) number_grays*number_grays*sum_squares.direction[i].alpha)-
         (variance.direction[i].alpha*variance.direction[i].alpha))/
@@ -1102,27 +1579,27 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
         (entropy_xy.direction[i].black-entropy_xy1.direction[i].black)/
         (entropy_x.direction[i].black > entropy_y.direction[i].black ?
          entropy_x.direction[i].black : entropy_y.direction[i].black);
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       channel_features[AlphaPixelChannel].measure_of_correlation_1[i]=
         (entropy_xy.direction[i].alpha-entropy_xy1.direction[i].alpha)/
         (entropy_x.direction[i].alpha > entropy_y.direction[i].alpha ?
          entropy_x.direction[i].alpha : entropy_y.direction[i].alpha);
     channel_features[RedPixelChannel].measure_of_correlation_2[i]=
-      (sqrt(fabs(1.0-exp(-2.0*(entropy_xy2.direction[i].red-
+      (sqrt(fabs(1.0-exp(-2.0*(double) (entropy_xy2.direction[i].red-
       entropy_xy.direction[i].red)))));
     channel_features[GreenPixelChannel].measure_of_correlation_2[i]=
-      (sqrt(fabs(1.0-exp(-2.0*(entropy_xy2.direction[i].green-
+      (sqrt(fabs(1.0-exp(-2.0*(double) (entropy_xy2.direction[i].green-
       entropy_xy.direction[i].green)))));
     channel_features[BluePixelChannel].measure_of_correlation_2[i]=
-      (sqrt(fabs(1.0-exp(-2.0*(entropy_xy2.direction[i].blue-
+      (sqrt(fabs(1.0-exp(-2.0*(double) (entropy_xy2.direction[i].blue-
       entropy_xy.direction[i].blue)))));
     if (image->colorspace == CMYKColorspace)
       channel_features[BlackPixelChannel].measure_of_correlation_2[i]=
-        (sqrt(fabs(1.0-exp(-2.0*(entropy_xy2.direction[i].black-
+        (sqrt(fabs(1.0-exp(-2.0*(double) (entropy_xy2.direction[i].black-
         entropy_xy.direction[i].black)))));
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       channel_features[AlphaPixelChannel].measure_of_correlation_2[i]=
-        (sqrt(fabs(1.0-exp(-2.0*(entropy_xy2.direction[i].alpha-
+        (sqrt(fabs(1.0-exp(-2.0*(double) (entropy_xy2.direction[i].alpha-
         entropy_xy.direction[i].alpha)))));
   }
   /*
@@ -1163,7 +1640,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
               pixel.direction[i].blue+=cooccurrence[x][y].direction[i].blue;
               if (image->colorspace == CMYKColorspace)
                 pixel.direction[i].black+=cooccurrence[x][y].direction[i].black;
-              if (image->alpha_trait == BlendPixelTrait)
+              if (image->alpha_trait != UndefinedPixelTrait)
                 pixel.direction[i].alpha+=
                   cooccurrence[x][y].direction[i].alpha;
             }
@@ -1183,7 +1660,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
             Q[z][y].direction[i].black+=cooccurrence[z][x].direction[i].black*
               cooccurrence[y][x].direction[i].black/
               density_x[z].direction[i].black/density_y[x].direction[i].black;
-          if (image->alpha_trait == BlendPixelTrait)
+          if (image->alpha_trait != UndefinedPixelTrait)
             Q[z][y].direction[i].alpha+=
               cooccurrence[z][x].direction[i].alpha*
               cooccurrence[y][x].direction[i].alpha/
@@ -1200,7 +1677,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
       if (image->colorspace == CMYKColorspace)
         channel_features[BlackPixelChannel].contrast[i]+=z*z*
           pixel.direction[i].black;
-      if (image->alpha_trait == BlendPixelTrait)
+      if (image->alpha_trait != UndefinedPixelTrait)
         channel_features[AlphaPixelChannel].contrast[i]+=z*z*
           pixel.direction[i].alpha;
     }
@@ -1217,7 +1694,7 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
     if (image->colorspace == CMYKColorspace)
       channel_features[BlackPixelChannel].maximum_correlation_coefficient[i]=
         sqrt((double) -1.0);
-    if (image->alpha_trait == BlendPixelTrait)
+    if (image->alpha_trait != UndefinedPixelTrait)
       channel_features[AlphaPixelChannel].maximum_correlation_coefficient[i]=
         sqrt((double) -1.0);
   }
@@ -1237,3 +1714,560 @@ MagickExport ChannelFeatures *GetImageFeatures(const Image *image,
   cooccurrence=(ChannelStatistics **) RelinquishMagickMemory(cooccurrence);
   return(channel_features);
 }
+\f
+/*
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%                                                                             %
+%                                                                             %
+%                                                                             %
+%     H o u g h L i n e I m a g e                                             %
+%                                                                             %
+%                                                                             %
+%                                                                             %
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%  Use HoughLineImage() in conjunction with any binary edge extracted image (we
+%  recommand Canny) to identify lines in the image.  The algorithm accumulates
+%  counts for every white pixel for every possible orientation (for angles from
+%  0 to 179 in 1 degree increments) and distance from the center of the image to
+%  the corner (in 1 px increments) and stores the counts in an accumulator matrix
+%  of angle vs distance. The size of the accumulator is 180x(diagonal/2). Next
+%  it searches this space for peaks in counts and converts the locations of the
+%  peaks to slope and intercept in the normal x,y input image space. Use the
+%  slope/intercepts to find the endpoints clipped to the bounds of the image. The
+%  lines are then drawn. The counts are a measure of the length of the lines
+%
+%  The format of the HoughLineImage method is:
+%
+%      Image *HoughLineImage(const Image *image,const size_t width,
+%        const size_t height,const size_t threshold,ExceptionInfo *exception)
+%
+%  A description of each parameter follows:
+%
+%    o image: the image.
+%
+%    o width, height: find line pairs as local maxima in this neighborhood.
+%
+%    o threshold: the line count threshold.
+%
+%    o exception: return any errors or warnings in this structure.
+%
+*/
+
+static inline double MagickRound(double x)
+{
+  /*
+    Round the fraction to nearest integer.
+  */
+  if ((x-floor(x)) < (ceil(x)-x))
+    return(floor(x));
+  return(ceil(x));
+}
+
+MagickExport Image *HoughLineImage(const Image *image,const size_t width,
+  const size_t height,const size_t threshold,ExceptionInfo *exception)
+{
+#define HoughLineImageTag  "HoughLine/Image"
+
+  CacheView
+    *image_view;
+
+  char
+    message[MagickPathExtent],
+    path[MagickPathExtent];
+
+  const char
+    *artifact;
+
+  double
+    hough_height;
+
+  Image
+    *lines_image = NULL;
+
+  ImageInfo
+    *image_info;
+
+  int
+    file;
+
+  MagickBooleanType
+    status;
+
+  MagickOffsetType
+    progress;
+
+  MatrixInfo
+    *accumulator;
+
+  PointInfo
+    center;
+
+  register ssize_t
+    y;
+
+  size_t
+    accumulator_height,
+    accumulator_width,
+    line_count;
+
+  /*
+    Create the accumulator.
+  */
+  assert(image != (const Image *) NULL);
+  assert(image->signature == MagickCoreSignature);
+  if (image->debug != MagickFalse)
+    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
+  assert(exception != (ExceptionInfo *) NULL);
+  assert(exception->signature == MagickCoreSignature);
+  accumulator_width=180;
+  hough_height=((sqrt(2.0)*(double) (image->rows > image->columns ?
+    image->rows : image->columns))/2.0);
+  accumulator_height=(size_t) (2.0*hough_height);
+  accumulator=AcquireMatrixInfo(accumulator_width,accumulator_height,
+    sizeof(double),exception);
+  if (accumulator == (MatrixInfo *) NULL)
+    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
+  if (NullMatrix(accumulator) == MagickFalse)
+    {
+      accumulator=DestroyMatrixInfo(accumulator);
+      ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
+    }
+  /*
+    Populate the accumulator.
+  */
+  status=MagickTrue;
+  progress=0;
+  center.x=(double) image->columns/2.0;
+  center.y=(double) image->rows/2.0;
+  image_view=AcquireVirtualCacheView(image,exception);
+  for (y=0; y < (ssize_t) image->rows; y++)
+  {
+    register const Quantum
+      *restrict p;
+
+    register ssize_t
+      x;
+
+    if (status == MagickFalse)
+      continue;
+    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
+    if (p == (Quantum *) NULL)
+      {
+        status=MagickFalse;
+        continue;
+      }
+    for (x=0; x < (ssize_t) image->columns; x++)
+    {
+      if (GetPixelIntensity(image,p) > (QuantumRange/2.0))
+        {
+          register ssize_t
+            i;
+
+          for (i=0; i < 180; i++)
+          {
+            double
+              count,
+              radius;
+
+            radius=(((double) x-center.x)*cos(DegreesToRadians((double) i)))+
+              (((double) y-center.y)*sin(DegreesToRadians((double) i)));
+            (void) GetMatrixElement(accumulator,i,(ssize_t)
+              MagickRound(radius+hough_height),&count);
+            count++;
+            (void) SetMatrixElement(accumulator,i,(ssize_t)
+              MagickRound(radius+hough_height),&count);
+          }
+        }
+      p+=GetPixelChannels(image);
+    }
+    if (image->progress_monitor != (MagickProgressMonitor) NULL)
+      {
+        MagickBooleanType
+          proceed;
+
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+        #pragma omp critical (MagickCore_CannyEdgeImage)
+#endif
+        proceed=SetImageProgress(image,CannyEdgeImageTag,progress++,
+          image->rows);
+        if (proceed == MagickFalse)
+          status=MagickFalse;
+      }
+  }
+  image_view=DestroyCacheView(image_view);
+  if (status == MagickFalse)
+    {
+      accumulator=DestroyMatrixInfo(accumulator);
+      return((Image *) NULL);
+    }
+  /*
+    Generate line segments from accumulator.
+  */
+  file=AcquireUniqueFileResource(path);
+  if (file == -1)
+    {
+      accumulator=DestroyMatrixInfo(accumulator);
+      return((Image *) NULL);
+    }
+  (void) FormatLocaleString(message,MagickPathExtent,
+    "# Hough line transform: %.20gx%.20g%+.20g\n",(double) width,
+    (double) height,(double) threshold);
+  if (write(file,message,strlen(message)) != (ssize_t) strlen(message))
+    status=MagickFalse;
+  (void) FormatLocaleString(message,MagickPathExtent,"viewbox 0 0 %.20g %.20g\n",
+    (double) image->columns,(double) image->rows);
+  if (write(file,message,strlen(message)) != (ssize_t) strlen(message))
+    status=MagickFalse;
+  line_count=image->columns > image->rows ? image->columns/4 : image->rows/4;
+  if (threshold != 0)
+    line_count=threshold;
+  for (y=0; y < (ssize_t) accumulator_height; y++)
+  {
+    register ssize_t
+      x;
+
+    for (x=0; x < (ssize_t) accumulator_width; x++)
+    {
+      double
+        count;
+
+      (void) GetMatrixElement(accumulator,x,y,&count);
+      if (count >= (double) line_count)
+        {
+          double
+            maxima;
+
+          SegmentInfo
+            line;
+
+          ssize_t
+            v;
+
+          /*
+            Is point a local maxima?
+          */
+          maxima=count;
+          for (v=(-((ssize_t) height/2)); v <= (((ssize_t) height/2)); v++)
+          {
+            ssize_t
+              u;
+
+            for (u=(-((ssize_t) width/2)); u <= (((ssize_t) width/2)); u++)
+            {
+              if ((u != 0) || (v !=0))
+                {
+                  (void) GetMatrixElement(accumulator,x+u,y+v,&count);
+                  if (count > maxima)
+                    {
+                      maxima=count;
+                      break;
+                    }
+                }
+            }
+            if (u < (ssize_t) (width/2))
+              break;
+          }
+          (void) GetMatrixElement(accumulator,x,y,&count);
+          if (maxima > count)
+            continue;
+          if ((x >= 45) && (x <= 135))
+            {
+              /*
+                y = (r-x cos(t))/sin(t)
+              */
+              line.x1=0.0;
+              line.y1=((double) (y-(accumulator_height/2.0))-((line.x1-
+                (image->columns/2.0))*cos(DegreesToRadians((double) x))))/
+                sin(DegreesToRadians((double) x))+(image->rows/2.0);
+              line.x2=(double) image->columns;
+              line.y2=((double) (y-(accumulator_height/2.0))-((line.x2-
+                (image->columns/2.0))*cos(DegreesToRadians((double) x))))/
+                sin(DegreesToRadians((double) x))+(image->rows/2.0);
+            }
+          else
+            {
+              /*
+                x = (r-y cos(t))/sin(t)
+              */
+              line.y1=0.0;
+              line.x1=((double) (y-(accumulator_height/2.0))-((line.y1-
+                (image->rows/2.0))*sin(DegreesToRadians((double) x))))/
+                cos(DegreesToRadians((double) x))+(image->columns/2.0);
+              line.y2=(double) image->rows;
+              line.x2=((double) (y-(accumulator_height/2.0))-((line.y2-
+                (image->rows/2.0))*sin(DegreesToRadians((double) x))))/
+                cos(DegreesToRadians((double) x))+(image->columns/2.0);
+            }
+          (void) FormatLocaleString(message,MagickPathExtent,
+            "line %g,%g %g,%g  # %g\n",line.x1,line.y1,line.x2,line.y2,maxima);
+          if (write(file,message,strlen(message)) != (ssize_t) strlen(message))
+            status=MagickFalse;
+        }
+    }
+  }
+  (void) close(file);
+  /*
+    Render lines to image canvas.
+  */
+  image_info=AcquireImageInfo();
+  image_info->background_color=image->background_color;
+  (void) FormatLocaleString(image_info->filename,MagickPathExtent,"mvg:%s",path);
+  artifact=GetImageArtifact(image,"background");
+  if (artifact != (const char *) NULL)
+    (void) SetImageOption(image_info,"background",artifact);
+  artifact=GetImageArtifact(image,"fill");
+  if (artifact != (const char *) NULL)
+    (void) SetImageOption(image_info,"fill",artifact);
+  artifact=GetImageArtifact(image,"stroke");
+  if (artifact != (const char *) NULL)
+    (void) SetImageOption(image_info,"stroke",artifact);
+  artifact=GetImageArtifact(image,"strokewidth");
+  if (artifact != (const char *) NULL)
+    (void) SetImageOption(image_info,"strokewidth",artifact);
+  lines_image=ReadImage(image_info,exception);
+  artifact=GetImageArtifact(image,"hough-lines:accumulator");
+  if ((lines_image != (Image *) NULL) &&
+      (IsStringTrue(artifact) != MagickFalse))
+    {
+      Image
+        *accumulator_image;
+
+      accumulator_image=MatrixToImage(accumulator,exception);
+      if (accumulator_image != (Image *) NULL)
+        AppendImageToList(&lines_image,accumulator_image);
+    }
+  /*
+    Free resources.
+  */
+  accumulator=DestroyMatrixInfo(accumulator);
+  image_info=DestroyImageInfo(image_info);
+  (void) RelinquishUniqueFileResource(path);
+  return(GetFirstImageInList(lines_image));
+}
+\f
+/*
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%                                                                             %
+%                                                                             %
+%                                                                             %
+%     M e a n S h i f t I m a g e                                             %
+%                                                                             %
+%                                                                             %
+%                                                                             %
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%  MeanShiftImage() delineate arbitrarily shaped clusters in the image. For
+%  each pixel, it visits all the pixels in the neighborhood specified by
+%  the window centered at the pixel and excludes those that are outside the
+%  radius=(window-1)/2 surrounding the pixel. From those pixels, it finds those
+%  that are within the specified color distance from the current mean, and
+%  computes a new x,y centroid from those coordinates and a new mean. This new
+%  x,y centroid is used as the center for a new window. This process iterates
+%  until it converges and the final mean is replaces the (original window
+%  center) pixel value. It repeats this process for the next pixel, etc., 
+%  until it processes all pixels in the image. Results are typically better with
+%  colorspaces other than sRGB. We recommend YIQ, YUV or YCbCr.
+%
+%  The format of the MeanShiftImage method is:
+%
+%      Image *MeanShiftImage(const Image *image,const size_t width,
+%        const size_t height,const double color_distance,
+%        ExceptionInfo *exception)
+%
+%  A description of each parameter follows:
+%
+%    o image: the image.
+%
+%    o width, height: find pixels in this neighborhood.
+%
+%    o color_distance: the color distance.
+%
+%    o exception: return any errors or warnings in this structure.
+%
+*/
+MagickExport Image *MeanShiftImage(const Image *image,const size_t width,
+  const size_t height,const double color_distance,ExceptionInfo *exception)
+{
+#define MaxMeanShiftIterations  100
+#define MeanShiftImageTag  "MeanShift/Image"
+
+  CacheView
+    *image_view,
+    *mean_view,
+    *pixel_view;
+
+  Image
+    *mean_image;
+
+  MagickBooleanType
+    status;
+
+  MagickOffsetType
+    progress;
+
+  ssize_t
+    y;
+
+  assert(image != (const Image *) NULL);
+  assert(image->signature == MagickCoreSignature);
+  if (image->debug != MagickFalse)
+    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
+  assert(exception != (ExceptionInfo *) NULL);
+  assert(exception->signature == MagickCoreSignature);
+  mean_image=CloneImage(image,image->columns,image->rows,MagickTrue,exception);
+  if (mean_image == (Image *) NULL)
+    return((Image *) NULL);
+  if (SetImageStorageClass(mean_image,DirectClass,exception) == MagickFalse)
+    {
+      mean_image=DestroyImage(mean_image);
+      return((Image *) NULL);
+    }
+  status=MagickTrue;
+  progress=0;
+  image_view=AcquireVirtualCacheView(image,exception);
+  pixel_view=AcquireVirtualCacheView(image,exception);
+  mean_view=AcquireAuthenticCacheView(mean_image,exception);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+  #pragma omp parallel for schedule(static,4) shared(status,progress) \
+    magick_threads(mean_image,mean_image,mean_image->rows,1)
+#endif
+  for (y=0; y < (ssize_t) mean_image->rows; y++)
+  {
+    register const Quantum
+      *restrict p;
+
+    register Quantum
+      *restrict q;
+
+    register ssize_t
+      x;
+
+    if (status == MagickFalse)
+      continue;
+    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
+    q=GetCacheViewAuthenticPixels(mean_view,0,y,mean_image->columns,1,
+      exception);
+    if ((p == (const Quantum *) NULL) || (q == (Quantum *) NULL))
+      {
+        status=MagickFalse;
+        continue;
+      }
+    for (x=0; x < (ssize_t) mean_image->columns; x++)
+    {
+      PixelInfo
+        mean_pixel,
+        previous_pixel;
+
+      PointInfo
+        mean_location,
+        previous_location;
+
+      register ssize_t
+        i;
+
+      GetPixelInfo(image,&mean_pixel);
+      GetPixelInfoPixel(image,p,&mean_pixel);
+      mean_location.x=(double) x;
+      mean_location.y=(double) y;
+      for (i=0; i < MaxMeanShiftIterations; i++)
+      {
+        double
+          distance,
+          gamma;
+
+        PixelInfo
+          sum_pixel;
+
+        PointInfo
+          sum_location;
+
+        ssize_t
+          count,
+          v;
+
+        sum_location.x=0.0;
+        sum_location.y=0.0;
+        GetPixelInfo(image,&sum_pixel);
+        previous_location=mean_location;
+        previous_pixel=mean_pixel;
+        count=0;
+        for (v=(-((ssize_t) height/2)); v <= (((ssize_t) height/2)); v++)
+        {
+          ssize_t
+            u;
+
+          for (u=(-((ssize_t) width/2)); u <= (((ssize_t) width/2)); u++)
+          {
+            if ((v*v+u*u) <= (ssize_t) ((width/2)*(height/2)))
+              {
+                PixelInfo
+                  pixel;
+
+                status=GetOneCacheViewVirtualPixelInfo(pixel_view,(ssize_t)
+                  MagickRound(mean_location.x+u),(ssize_t) MagickRound(
+                  mean_location.y+v),&pixel,exception);
+                distance=(mean_pixel.red-pixel.red)*(mean_pixel.red-pixel.red)+
+                  (mean_pixel.green-pixel.green)*(mean_pixel.green-pixel.green)+
+                  (mean_pixel.blue-pixel.blue)*(mean_pixel.blue-pixel.blue);
+                if (distance <= (color_distance*color_distance))
+                  {
+                    sum_location.x+=mean_location.x+u;
+                    sum_location.y+=mean_location.y+v;
+                    sum_pixel.red+=pixel.red;
+                    sum_pixel.green+=pixel.green;
+                    sum_pixel.blue+=pixel.blue;
+                    sum_pixel.alpha+=pixel.alpha;
+                    count++;
+                  }
+              }
+          }
+        }
+        gamma=1.0/count;
+        mean_location.x=gamma*sum_location.x;
+        mean_location.y=gamma*sum_location.y;
+        mean_pixel.red=gamma*sum_pixel.red;
+        mean_pixel.green=gamma*sum_pixel.green;
+        mean_pixel.blue=gamma*sum_pixel.blue;
+        mean_pixel.alpha=gamma*sum_pixel.alpha;
+        distance=(mean_location.x-previous_location.x)*
+          (mean_location.x-previous_location.x)+
+          (mean_location.y-previous_location.y)*
+          (mean_location.y-previous_location.y)+
+          255.0*QuantumScale*(mean_pixel.red-previous_pixel.red)*
+          255.0*QuantumScale*(mean_pixel.red-previous_pixel.red)+
+          255.0*QuantumScale*(mean_pixel.green-previous_pixel.green)*
+          255.0*QuantumScale*(mean_pixel.green-previous_pixel.green)+
+          255.0*QuantumScale*(mean_pixel.blue-previous_pixel.blue)*
+          255.0*QuantumScale*(mean_pixel.blue-previous_pixel.blue);
+        if (distance <= 3.0)
+          break;
+      }
+      SetPixelRed(mean_image,ClampToQuantum(mean_pixel.red),q);
+      SetPixelGreen(mean_image,ClampToQuantum(mean_pixel.green),q);
+      SetPixelBlue(mean_image,ClampToQuantum(mean_pixel.blue),q);
+      SetPixelAlpha(mean_image,ClampToQuantum(mean_pixel.alpha),q);
+      p+=GetPixelChannels(image);
+      q+=GetPixelChannels(mean_image);
+    }
+    if (SyncCacheViewAuthenticPixels(mean_view,exception) == MagickFalse)
+      status=MagickFalse;
+    if (image->progress_monitor != (MagickProgressMonitor) NULL)
+      {
+        MagickBooleanType
+          proceed;
+
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+        #pragma omp critical (MagickCore_MeanShiftImage)
+#endif
+        proceed=SetImageProgress(image,MeanShiftImageTag,progress++,
+          image->rows);
+        if (proceed == MagickFalse)
+          status=MagickFalse;
+      }
+  }
+  mean_view=DestroyCacheView(mean_view);
+  pixel_view=DestroyCacheView(pixel_view);
+  image_view=DestroyCacheView(image_view);
+  return(mean_image);
+}