https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=30147

diff --git a/MagickCore/composite.c b/MagickCore/composite.c
index 1758a4225d7c7e9a33037ae46367d9bed9f8efc0..1bf5ca3934fa9140ca9c2ea1fcda88adbb0030cd 100644 (file)
--- a/MagickCore/composite.c
+++ b/MagickCore/composite.c
@@ -1602,7 +1602,7 @@ MagickExport MagickBooleanType CompositeImage(Image *image,
               }
               case CopyAlphaCompositeOp:
               {
-                if ((source_traits & BlendPixelTrait) == 0)
+                if (source_image->alpha_trait == UndefinedPixelTrait)
                   pixel=GetPixelIntensity(source_image,p);
                 else
                   pixel=QuantumRange*Sa;