[argyllcms] Re: Warning: gamut mapping is non monotonic - may be not very smooth
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 28 May 2012 10:08:28 +1000
Michael Schulz wrote:
>> You'll never get a good result for ProPhoto unless you constrain the
>> source gamut - ProPhoto
>> has a stupidly large gamut with imaginary primaries, and compressing down
>> from
>> that will typically give a very bad result.
>
> What is the best way to constrain the source gamut? Desaturating the image
> inside Photoshop (dynamic correction), RGB to RGB conversion (ProPhoto to
> AdobeRGB, ...)?
Hi,
You're misunderstand me - I meant constrain the gamut given to
the gamut mapping, not constrain the images gamut. They are not
necessarily the same thing :- in typical ICC workflows the source
gamut is taken to be that of the colorspace. When the colorspace
is very wide gamut, that is an issue.
> The image for the source gamut is in 16 bits. I desaturated the source
> image slightly inside Photoshop (dynamic correction) and used -qu for the
> device link which eliminates the color banding in the gradients. What
> remains is a clipping(?) - small white shine between red leaves and blue
> background.
Without examining the details, it's hard to comment. The right
workflow when working with very wide gamut source colorspaces is
to measure the gamut of the images, and use that (or something
of a similar nature) as the source gamut for gamut mapping.
Graeme Gill.
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