Implement softproofing cmyk histogram

[jenshannoschwalm]

While using a cmyk profile for histograms we had to fallback to a rgb profile supported in _transform_rgb_to_rgb_lcms2.

Instead of doing so we properly check for a cmyk to-profile, if so we use a softproofing xtrans operator instead inside _transform_rgb_to_rgb_lcms2.

[TurboGit]

@jenshannoschwalm : A conflict resolution is needed here. TIA.

[jenshannoschwalm]

Release note: Added support for CMYK profiled histogram

[johnlb]

I'm trying to use this with a cmyk soft-proof profile provided by Bay Photo and, while the histogram is showing now (thanks for the great work on that!), there is nothing in the vectorscope (see image). Is this expected behavior at this point, or should I open a new ticket?

Screenshot is from v4.9.0, but I've seen it on 4.8.0 as well.

[jenshannoschwalm]

Please share the profile, will have a look.

[johnlb]

Had to put it in a zip file to upload, but here ya go.

BayPhoto_MetalPrints.zip

[jenshannoschwalm]

Thanks, it seems it sometimes works sometimes it doesn't. Will check

[johnlb]

Oh huh. I haven't seen it work at all yet. When you say sometimes it works, are you toggling between soft proofing on/off or switching between histogram modes or something?

On Tue, Jun 18, 2024, 10:42 AM Hanno Schwalm @.***> wrote:

Thanks, it seems it sometimes works sometimes it doesn't. Will check

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[jenshannoschwalm]

It seems to work safely with this

EDIT: for some reason i don't yet understand (likely some vectorscope magic) this only works in RYB mode.