https://github.com/ImageMagick/ImageMagick/issues/594

diff --git a/MagickCore/attribute.c b/MagickCore/attribute.c
index 43ee6b3e2eadb132c4a04300318a138096b79d1f..1d822b82e7d5793e28dbe2cf6726da5283a33700 100644 (file)
--- a/MagickCore/attribute.c
+++ b/MagickCore/attribute.c
@@ -1255,15 +1255,7 @@ MagickExport MagickBooleanType SetImageType(Image *image,const ImageType type,
     case BilevelType:
     {
       if (SetImageMonochrome(image,exception) == MagickFalse)
-        {
-          status=TransformImageColorspace(image,GRAYColorspace,exception);
-          (void) NormalizeImage(image,exception);
-          quantize_info=AcquireQuantizeInfo(image_info);
-          quantize_info->number_colors=2;
-          quantize_info->colorspace=GRAYColorspace;
-          status=QuantizeImage(quantize_info,image,exception);
-          quantize_info=DestroyQuantizeInfo(quantize_info);
-        }
+        status=AutoThresholdImage(image,UndefinedThresholdMethod,exception);
       image->alpha_trait=UndefinedPixelTrait;
       break;
     }