[argyllcms] Re: cmyk printer profiles
- From: Vladimir Gajic <vgajic67@xxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 26 Mar 2010 09:32:47 +0100
Hello Nikolay,
I can see your point about AdobeRGB vs. eciRGB. It would be logical and I
tried that one also. The result is in deed more correct -but AdobeRGB simply
performs better, especially in high-saturated reds. There is a lot more
modulation and structure visible. The skintones are slightly more yellowish,
witch I don´t really see as a problem (the image will be colour-corrected in
Photoshop anyway).
The black generation curve I posted had to achieve 2 basic targets:
1. To generate a UCR - separation (as mutch as possible)
2. The separations should be smooth (eg. when converting a LAB gradient
[100, 0, 0 to 0, 0, 0])
I tried also to generate profiles where K is rather a locus (witch complies
to basiccolor or HDB-profiles). After running xicclu -v -g -fb -ip -o, the
curves complied to the visual look of my separations generated from the
previous mentioned LAB-gradient. That means that they were not as smooth as
in the -kp-example I´ve posted allready.
I´ll try some other black generation curves anyway. Thank´s for the link you
posted -maybe I´ll find my answers there.
Regards
Vladimir
2010/3/26 Nikolay Pokhilchenko <nikolay_po@xxxxxxx>
> Vladimir Gajic wrote:
>
> > Hi Graeme,
> >
> > after converting an RGB-image (roman16) from eciRGB_v2 or AdobeRGB to my
> > fogra39 profile, magenta and cyan primaries appear far to dirty. Here
> are
> > some values:
> >
> > eciRGB (Photoshop)
> > Cyan: 61/138/194 -> 83/10/5/32
> > Magenta: 174/59/134 -> 0/85/9/29
> >
> > That s at least 10-15% too much black in both colours. Since the
> transition
> > is very smooth, I really don t have any problem correcting them. Anyway,
> my
> > profile params are:
> > -l330 -L95 -kp 0.00 0.18 0.98 0.95 0.55 -al -s AdobeRGB -np -tp -dpp
>
> Hello, Vladimir, I suppose this is because the black generation in Argyll
> colprof/collink/xicclu is "wide", the black penetrates into the saturated
> area until it conforms the black curve settings.
> Take a look into
> //www.freelists.org/post/argyllcms/colprof-and-proofing-purposes
>
> Anorher thing: Yo've done the mapping from AdobeRGB, but do the conversion
> from eciRGB. IMHO it will be more correct to do the mapping from eci.RGB (-s
> eciRGB) in this case.
>
>
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