https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=32484

diff --git a/MagickCore/channel.c b/MagickCore/channel.c
index 4792927ed7203f1bfaf12edc2581c75669199af0..81939aa363f5db76de480589bf147ff89e336052 100644 (file)
--- a/MagickCore/channel.c
+++ b/MagickCore/channel.c
@@ -727,6 +727,7 @@ MagickExport Image *SeparateImage(const Image *image,
       return((Image *) NULL);
     }
   (void) SetImageColorspace(separate_image,GRAYColorspace,exception);
+  separate_image->intensity=Rec709LuminancePixelIntensityMethod;
   separate_image->alpha_trait=UndefinedPixelTrait;
   /*
     Separate image.