https://github.com/ImageMagick/ImageMagick/issues/1477

diff --git a/coders/gif.c b/coders/gif.c
index d62ba437f4e69b6d29ceaadc0c1369b6d9f40026..24781a1171077956938bb45a83b8c3126fc4a006 100644 (file)
--- a/coders/gif.c
+++ b/coders/gif.c
@@ -1271,7 +1271,10 @@ static Image *ReadGIFImage(const ImageInfo *image_info,ExceptionInfo *exception)
       ((size_t) (flag & 0x07)+1);
     image->colors=local_colors;
     if (opacity >= (ssize_t) image->colors)
-      opacity=(-1);
+      {
+        image->colors++;
+        opacity=(-1);
+      }
     image->ticks_per_second=100;
     image->alpha_trait=opacity >= 0 ? BlendPixelTrait : UndefinedPixelTrait;
     if ((image->columns == 0) || (image->rows == 0))