[argyllcms] Re: Question about DeltaE from printread and one about iccexamin/profcheck
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 10 Sep 2007 21:57:06 +0200
Lars Tore Gustavsen wrote:
> Another long question. Basically I ask what can explain a high
> printread DeltaE, and a question about differences between profcheck
> and iccexamin.
>
> Yesterday I printed an RGB 528 patch target. When I read it today with
> printread I got this warning when I tried to read two of the strips:
>
>
> About to read strip pass F
>
> Trigger instrument switch or any key to start, Esc, ^C or Q to give up:
>
>
> There is at least one patch with an very unexpected response! (DeltaE
> 82.860992)
>
> Hit Return to use it anyway, any other key to retry, Esc, ^C or Q:
>
>
> After I reread the same row a few times I hited enter and accepted
> this. Maybe it would be more correct to trash the target and start
> over again? Or can this be related to question I asked a month ago
> about printtarg and DeltaE. I think the DeltaE that printarg reported
> on this target was about 90% after optimization.
> Anyway, afterwards when I build the profile I got this messages:
> profile -v -D"RGB-luster test4" -qm -S sRGB.icm -cmt -dpp test4
>
> profile check complete, peak err = 7.405302, avg err = 1.056087
>
>
> I then played with different text utility and deleted all
> measurements in the ti3 file from row F. I then got this result when
> I made the profile without the F row.
> profile check complete, peak err = 7.345448, avg err = 1.044123
>
>
> I guess this mean that that this patch is skipped in the profile
> creation? I tested the profile on a PDI target and I am actually very
> please with what I saw. I just wonder what can be wrong with my
> target. Can there be a patch outside the printers gamut?
>
> I tried so to identify this patch. If I take a look at the output from
> profcheck from row F the one with highest Delta E is patch 6:
> Profile check complete, errors: max. = 7.405302, avg. = 1.056087, RMS =
> 1.331468
>
> [0.571890] 1.000000 0.000000 0.000000 -> 50.490826 70.709652
> 65.121628 should be 50.464170 70.820274 64.561172
>
> However icc_examin gives me this result for the profile:
> averaging deviations (dE CIE*Lab): 36.5161 maximum: 67.1216 minimum:
> 0.739298 (dE CIE 2000) averaging: 14.9649 maximum: 21.93 minimum:
> 0.670952
> and patch 6
> dE Lab dE2000
> 46.638 12.9499
> Take a look at http://www.mulebakken.net/div/iccexamin.html for a
> more readable cutted down iccexamin report for row F only.
>
> For me this is quit confusing, but I guess there is a explanation on
> this. The differences on the reported Delta E on the patch from 0.5
> to 46 is quite big. And for the whole file difference between avg
> error 1.04 to 36.52 is quite big. Can someone pleas teach me?
>
> (Kai-Uwe, there was a bug in iccexamin that don't allowed me to save
> the report if the html file not existed)
>
> Where can I put the DeltaE 82.860992 that printread talks about in
> this landscape.
Possibly you can ignore it. I suggest that you measure the suspect patch
with spotread again. And if the numbers you get are very close to the
numbers you got in the .ti3 file, then it is IMO OK to ignore it.
(My understanding is, if you don't call targen with the "-c <profile>"
option, then the XYZ numbers in the .ti1 and .ti2 files are just a very
rough guess, which may not fit well with your printer's response at all,
so sporadically "unjustified complaints" from printread may happen for
some patches)
Regards,
Gerhard
> Regards
> Lars Tore Gustavsen
>
> ti2
> SAMPLE_ID SAMPLE_LOC RGB_R RGB_G RGB_B XYZ_X XYZ_Y XYZ_Z
> 6 "F5" 100.00 0.0000 0.0000 41.830 22.052 2.9132
>
> ti3
> SAMPLE_ID RGB_R RGB_G RGB_B XYZ_X XYZ_Y XYZ_Z
> 6 100.00 0.0000 0.0000 35.186 18.810 1.2915 50.464 70.819 64.561
>
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