Andrej Javoršek wrote:
I would like to get comment on my approach to get the smallest possible (but still useful) patch amount for
quick profiling of news print offset press. My motivation is to be able to profile press with small amount of
patches that can be printed during normal press run (without need for common test-chart print run).
Patches should be printed in border (cut off) area of paper so probably I could only print some 50 to 100 patches.
The approach I'm considering is to first (and only once) print really big test chart (4000 to 5000 patches) and measure it.
After that I could use "splitcgats" to get fraction of those measurements, create profile with that fraction and use "profcheck"
against the whole set to get dE for that set. I can repeat "splitcgats" 500 or 1000 times to get statistically good representation.
I could repeat same test for 2 or maybe 3 different papers to se if patch set is more or less the same for them.
While it sounds reasonable, I would guess that you mightn't get what you are hoping for. My guess, is that you would find that all the subsets are much like each other, with random variations, and that after picking your best subset, that if you then compare that against what targen -f100 or -f50, that the results will also be fairly similar, if not better. You should also try using targen -f100 -A0.5 as a check, as well. ie., that there is no "magic" subset of colors that generates a significantly better quality profile to be found, there are just "slightly better" subsets.
Now for generating profiles from well behaved devices (like presses), with really small numbers of patchs (say 20 or so), I have tried another approach, with mixes success.
This is to use profile/mpprof to generate an mpp profile, and then use fakeread with 5000 test patches or so and the mpp profile, to generate a test set that can be fed into profile to generate a conventional icc profile. (I was thinking also that I could alter profile to directly generate an ICC profile from an mpp profile, but have never got around to that.)
Graeme.
