[argyllcms] Re: Verifying profile quality of LUT-based scanner and printer profiles


Possibly you're more interested in saturation that lightness matching,
so the current releases emphasis on lightness matching doesn't suite
your goals.

I'm not sure I could say with certainty what my goals are yet ! :-) In any case, I suspect that the profile I will get at the end of the day, even with flatbed scanning, will be much better than I would have dreamed possible without actually spending money on commercial profiling hw/sw, which would of course be a nonsense thing to do with a printer like this. At the moment, I'm just seeing how far I can push the envelope, and in the process I'm learning a lot of interesting stuff!

The claim that "sRGB has a really small gamut" is
rather a simplification and exaggeration. What perhaps is really
meant, is that it does not cover a lot of gamut that is captured
by photographic film, or printable by many printers. There is still
a lot of sRGB gamut that can't be printed on any printer!

Yes I can see that now!

If the shape of the gamut skin has any significant non-linearities in it, I imagine it is possible that these are not necessarily smoothed out just because of using Perceptual rendering intent? Or, is it possible that you can still get banding with Perceptual rendering intent for some other reason? 

Perceptual intent at least tries to smoothly bend the source gamut
to fit the destination gamut. Colorimetric simply maps to the
closes destination color, clipping if it is out of gamut. There
will therefore be an edge when clipping starts, and (worse than
this), the shape of the gamut may be such that there are abrupt
transitions from one point on the destination being closest,
and another point being closest (think of a Voronoi diagram).
I can see this happening....I'm not even going to ask what a Voronoi diagram is...

This is often the case. For most uses, I'd tend to use "medium" quality,
and only try something else if there is a particular reason to do so.

Interesting. Intuitively one would expect that more resolution = better, but as you say this is not always the case. So I presume if the avg dE and peak is not that much different between -qm and -qh or -qu then better to go with -qm? Would you say this applies to scanner profiles as well?

Also, should the -r 1.0 recommendation be used when creating printer profiles as well as scanner profiles?

Milt

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