Legacy ImageMagick Discussions Archive

IM 6.7.2.9 Q16 Mac OSX Tiger.

This is not urgent as there is an alternate way to do this with -compose multiply -flatten, but I thought I would report it anyway.

convert -size 100x100 xc:gray gray.png
convert gray.png gray.png -evaluate-sequence multiply gray2.png

I would expect the result to be at graylevel 25% (.5x.5x100) from two gray images of graylevel 50%. But the result is full white. There are no error messages of any kind, esp, about multiply not being a valid option to -evaluate-sequence

Fred

We can reproduce the problem you posted and have a patch in ImageMagick 6.7.2-10 Beta available by sometime tomorrow. Thanks.

Also there is no -list EvaluateSequence to list just what methods are available to that option.

Did this ever get implemented? The following does not seem to finish and does not issue an error?

convert -size 100x100 xc:gray gray.png
convert gray.png gray.png -evaluate-sequence multiply gray2.png

IM 6.7.3.1 Q16 Mac OSX Tiger


When/if it gets implemented, will it multiply the existing alpha channels in the images, if using -channel rgba -alpha on?

Curious, the command works for ImageMagick 7.0.0 but hangs in 6.7.3. We'll investigate and get a patch into 6.7.3 in the next few days.

Thanks.