[argyllcms] Re: Warning: gamut mapping is non monotonic - may be not very smooth
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 24 May 2012 19:49:50 +1000
Michael Schulz wrote:
> this warning appears while I made a device link profile from ProPhotoRGB.icc
> to ISOcoated_v2.icc
> using the gamut of a particular image (collink –qh –ke –cmt –dpp –ip –G
> ProPhotoRGB.gam
> imageRGB.tif ISOcoated_v2.icc DL_ProPhotoRGB-ISOcoated_v2.icc).
> This DL produces much better color appearance than normal conversion from
> ProPhotoRGB to
> ISOcoated_v2 in Photoshop but does have slight color banding in gradients.
Hi,
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.
> Could somebody explain to me the meaning of the warning message and is there
> a possible way
> avoiding color banding when creating DL from a large to a small gamut.
The warning is technical - it's not clear to me what the implications if any
are,
other than hinting that the geometry of source to destination is not
particularly smooth.
This is probably not unexpected for a real image source gamut. It doesn't
necessarily
have anything to do with the banding.
The banding could be because 8 bits in ProPhoto is quantizing the image,
it could be because the profile has limited precision or was the result
of noisy data, it could be that the resolution of the device link is too low.
Hard to know without a detailed and length investigation.
Graeme Gill.
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