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Colorspace conversions when not called

Posted: 2019-10-29T15:21:49-07:00
by btully
Running 7.0.8-68 on Mac OS X 14.6
Called from command line.
Arguments are [source path, -resize 10%, -flatten, destination path]

Images are converting from CMYK to RGB, maintaining the same ICC profile.
Visually, images are inverting, like a film negative.

Input files are CMYK TIFFs, SWOP3, 7000 + pixels on the long side.
Output are JPEGs.

Updating the arguments to
[source path, -colorspace RGB, -resize 10%, -flatten, -colorspace CMYK, destination path]
prevents the inversion, but dramatically darkens the image.

previous version, 7.0.8-47 worked normally

Re: Colorspace conversions when not called

Posted: 2019-10-29T15:31:12-07:00
by btully
Running arguments
[source path, -colorspace CMYK, -resize 10%, -flatten, -colorspace CMYK, destination path] or
[source path, -resize 10%, -flatten, -colorspace CMYK, destination path]
both produce CMYK images, but same inversion of colors.

Re: Colorspace conversions when not called

Posted: 2019-10-29T15:43:36-07:00
by snibgo
I confirm that this used to work in 7.0.7-28, but fails in 7.0.8-64.

The problem is that "-flatten" changes the colorspace to sRGB. It shouldn't, so this seems to be a bug.

A workaround for this example is "-set colorspace CMYK" after "-flatten".

Re: Colorspace conversions when not called

Posted: 2019-10-30T07:55:36-07:00
by btully
snibgo,
Thank you for the workaround. I am using that with success.