https://github.com/ImageMagick/ImageMagick/issues/1584

diff --git a/MagickCore/quantize.c b/MagickCore/quantize.c
index 9f3124718c006be32f5aa82ec3c9cbbe321fca95..812f6d8c08666011a9ed22bf2b759b82076ede50 100644 (file)
--- a/MagickCore/quantize.c
+++ b/MagickCore/quantize.c
@@ -2674,7 +2674,8 @@ MagickExport MagickBooleanType QuantizeImage(const QuantizeInfo *quantize_info,
       if (SetImageGray(image,exception) != MagickFalse)
         (void) SetGrayscaleImage(image,exception);
     }
-  if ((image->storage_class == PseudoClass) &&
+  if ((quantize_info->dither_method == NoDitherMethod) &&
+      (image->storage_class == PseudoClass) &&
       (image->colors <= maximum_colors))
     {
       if ((quantize_info->colorspace != UndefinedColorspace) &&