Make alpha channel backwards compatible with IMv6

diff --git a/coders/miff.c b/coders/miff.c
index cb87535473c0adfce01da02abb613361c221139f..41243c192a1c335d688aeae4fad302fc44188e05 100644 (file)
--- a/coders/miff.c
+++ b/coders/miff.c
@@ -2056,6 +2056,8 @@ static MagickBooleanType WriteMIFFImage(const ImageInfo *image_info,
       CommandOptionToMnemonic(MagickPixelTraitOptions,(ssize_t)
       image->alpha_trait));
     (void) WriteBlobString(image,buffer);
+    if (image->alpha_trait != UndefinedPixelTrait)
+      (void) WriteBlobString(image,"matte=True\n");
     (void) FormatLocaleString(buffer,MagickPathExtent,
       "columns=%.20g  rows=%.20g  depth=%.20g\n",(double) image->columns,
       (double) image->rows,(double) image->depth);