magick -gamma 0 does not produce black image

[pgajdos]

The result of

magick test.png -gamma 0 -alpha off black_gamma.png

does not produce all-black image as described in https://usage.imagemagick.org/canvas/, but:

This is similar to ImageMagick/ImageMagick#1151

Tested with 7.1.1-43.

[pgajdos]

magick convert produces expected result, i. e. all-black image.

[fmw42]

I believe that there is a bug in -gamma. It is not processing the rgb channels properly on certain images. When I do.

magick logo: -transparent white logot.png

magick logot.png -gamma 0 -alpha off x.png

But the result should be totally black.

I have also tried

magick logot.png -alpha off -channel rgb -gamma 0 x.png

and

magick logot.png -alpha deactivate -gamma 0 x.png

but get the same results.

This is strange

This fails:
magick logo: -gamma 0 -alpha off y.png

and also

magick lena.png -gamma 0 -alpha off z.png

So it looks like the red channel is not processed or possibly pure red, not processed.

[urban-warrior]

Thank you for reporting the issue. We have successfully reproduced it and are actively working on a patch to resolve it. You can expect this patch to be merged into the main GIT branch, later today. As part of our commitment to quality, this fix will also be included in the upcoming beta releases of ImageMagick by tomorrow. Your patience and feedback are greatly appreciated.

[pgajdos]

Thank you, recent changes in git fixed the behavior for me.