[argyllcms] Re: icclink -G and source gamuts /-profiles
- From: "Alastair M. Robinson" <profiling@xxxxxxxxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sun, 11 May 2008 12:23:54 +0100
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
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