[argyllcms] Re: Profiling flexo presses


Roger,

Roger Breton schrieb:

that table wastes 70% or so of the space
in colors that are either nonexistent or out of gamut.

You wonder why couldn't there be some scaling factor that allows making
intelligent use of the encoding space.

I've seen profiles with S-shaped input tables for the a* and b* channels of the B2A luts (I don't remember exactly, but I think these were profiles made by ProfileMaker). This results in higher resolution for low-chromatic colors, and a lower resolution for highly chromatic colors (many/most of them are usually out-of-gamut anyway). Argyll profiles are apparently not built in this way.

Most CMYK profiles I seen only have 17x17x17

Actually it is not 17^3, but 17^4 for the A2B tables, since CMYK has 4 channels.

I was once told that increasing the grid resolution would create monster 
profiles?

Sure, doubling the resolution increases the CMYK A2B CLUT by a factor of 16=2^4.

Please excuse my ignorance, but you mean I could create such profiles with
argyll? 41 grid points both ways?

A brief look at the profout.c reveals that -qu implies 23 A2B CLUT grid points (for CMYK), and 45 B2A grid points. But I'm not sure whether you'll have enough patience for -qu :-)

Regards,
Gerhard



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