https://github.com/ImageMagick/ImageMagick/issues/4059

ImageMagick · Sep 6, 2021 · 9d97e95 · 9d97e95
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commit 9d97e95
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Showing 3 changed files with 23 additions and 15 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,10 @@
+2021-09-06  6.9.12-22  <quetzlzacatenango@image...>
+  * Release ImageMagick version 6.9.12-21 GIT revision 16...
+
+2021-09-06  6.9.12-22  <quetzlzacatenango@image...>
+  * prevent color reduction merging into one color (reference
+    https://github.com/ImageMagick/ImageMagick/issues/4059).
+
 2021-09-04  6.9.12-21  <quetzlzacatenango@image...>
   * Release ImageMagick version 6.9.12-21 GIT revision 16778:e0967eae2:20210904
 

diff --git a/magick/attribute.c b/magick/attribute.c
@@ -1578,10 +1578,9 @@ MagickExport MagickBooleanType SetImageType(Image *image,const ImageType type)
       (void) NormalizeImage(image);
       quantize_info=AcquireQuantizeInfo(image_info);
       quantize_info->number_colors=2;
-      quantize_info->dither_method=FloydSteinbergDitherMethod;
+      quantize_info->colorspace=GRAYColorspace;
       status=QuantizeImage(quantize_info,image);
       quantize_info=DestroyQuantizeInfo(quantize_info);
-      status=MinMaxStretchImage(image,0.0,0.0,1.0);
       image->matte=MagickFalse;
       break;
     }

diff --git a/magick/quantize.c b/magick/quantize.c
@@ -624,8 +624,7 @@ static MagickBooleanType AssignImageColors(Image *image,CubeInfo *cube_info)
   if (cube_info->quantize_info->measure_error != MagickFalse)
     (void) GetImageQuantizeError(image);
   if ((cube_info->quantize_info->number_colors == 2) &&
-      ((cube_info->quantize_info->colorspace == LinearGRAYColorspace) ||
-       (cube_info->quantize_info->colorspace == GRAYColorspace)))
+      (IsGrayColorspace(cube_info->quantize_info->colorspace)))
     {
       double
         intensity;
@@ -2484,17 +2483,20 @@ static void PruneChild(CubeInfo *cube_info,const NodeInfo *node_info)
   for (i=0; i < (ssize_t) number_children; i++)
     if (node_info->child[i] != (NodeInfo *) NULL)
       PruneChild(cube_info,node_info->child[i]);
-  /*
-    Merge color statistics into parent.
-  */
-  parent=node_info->parent;
-  parent->number_unique+=node_info->number_unique;
-  parent->total_color.red+=node_info->total_color.red;
-  parent->total_color.green+=node_info->total_color.green;
-  parent->total_color.blue+=node_info->total_color.blue;
-  parent->total_color.opacity+=node_info->total_color.opacity;
-  parent->child[node_info->id]=(NodeInfo *) NULL;
-  cube_info->nodes--;
+  if (cube_info->nodes > cube_info->maximum_colors)
+    {
+      /*
+        Merge color statistics into parent.
+      */
+      parent=node_info->parent;
+      parent->number_unique+=node_info->number_unique;
+      parent->total_color.red+=node_info->total_color.red;
+      parent->total_color.green+=node_info->total_color.green;
+      parent->total_color.blue+=node_info->total_color.blue;
+      parent->total_color.opacity+=node_info->total_color.opacity;
+      parent->child[node_info->id]=(NodeInfo *) NULL;
+      cube_info->nodes--;
+    }
 }
 
 /*