Hi :) Klaus Karcher wrote:
In Photoshop. I selected ProPhotoRGB as RGB working space, switched to "Custom RGB" (Photoshop adopts the key data from PhroPhotoRGB), changed the Gamma to 1 and saved the setting as ICC profile.
OK. And does your scanner (or camera?) profile have a similar gamma? Or was the idea to use linear RGB for denoising?
Also, how was your scanner/camera profile generated? I take it it's not an Argyll profile?
Yes, it's the same (I tried AdobeRGB). Even the "Normal Proof" in imgtarget looks completely wrong when using the Gamma 1 source image. The same conversion in Photoshop is ok.
Interesting.
And you use lcms for the transformations, don't you?
Yes, that's right - so it seems both Argyll and LCMS have issues with a gamma 1.0 input profile. The behaviour of both system improves rapidly as the gamma increases, though - at a cursory glance, LCMS seems fine at 1.1, cctiff without the -p flag seems accurate enough at 1.3 or so (and with -p, of course, is fine even at 1.0)
So what do the input curves of your scanner/camera profile look like compared with RGB profiles with various gammas?
All the best, -- Alastair M. Robinson