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Re: [Lcms-user] odd change in 2.13
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From: Derek B. N. <de...@gl...> - 2022-03-24 22:31:14
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Thanks. I can confirm that the current github code fixes the problem
I was seeing.
- Derek
On Thu, 24 Mar 2022 15:53:05 +0100
mar...@li... wrote:
> Hi,
>
> Thanks for reporting the issue. The reason for getting same results
> was both programs were using same *.so and therefore both were using
> 2.13
>
> Actually the issue was due to a bug, that was there from the old days
> but was not triggered because unbounded mode was limited.
> Now, 2.13 has extended unbounded mode support and some profiles, like
> the one you sent, can work in such conditions. For relative
> colorimetric, the profile reports a L* of -400, which is obviously
> out of gamut. 2.12 didn't obtain this value because didn't handle
> such extended values and returned zero. 2.13 does, and unfortunately
> there was no code on BPC algorithm to clip negative L* to zero. As a
> result the black point was detected wrongly.
>
> This bug needs a particular profile and also needs a transform using
> black point compensation. Not very common. It is now fixed in github
>
> Regards
> Marti
>
>
>
> On 2022-03-23 21:03, Derek B. Noonburg wrote:
> > Thanks for taking a look at this.
> >
> > On Wed, 23 Mar 2022 14:37:35 +0100
> > Marti Maria <mar...@li...> wrote:
> >
> >> > On 22 Mar 2022, at 23:10, Derek B. Noonburg
> >> > <de...@gl...> wrote:
> >> >
> >> > I'm seeing very different output in one particular case, after
> >> > upgrading from 2.12 to 2.13 (or 2.13.1).
> >> >
> >>
> >> Checked your profile and gives same results to me, tested on Debian
> >> 11, system lcms2 (from Debian, which is 2.12) vs. compilation of
> >> 2.13 on /usr/local
> >>
> >> marti@debian:~$ /usr/bin/transicc -c1 -s -ex -i profile.icc -b -t1
> >> ...
> >
> > There's something strange going on here. I can reproduce my results
> > with transicc, so I'm pretty sure it's not an issue with transicc
> > vs my sample code.
> >
> > I just rebuilt lcms 2.12 and 2.13.1 on my Linux system (Slackware
> > 14.2, gcc 5.5.0), and I get this:
> >
> > $ ./lcms212/bin/transicc -c1 -s -ex -i profile.icc -b -t1
> > LittleCMS ColorSpace conversion calculator - 5.0 [LittleCMS 2.12]
> > Copyright (c) 1998-2020 Marti Maria Saguer. See COPYING file for
> > details.
> >
> > Enter values, 'q' to quit
> > R? 97
> > G? 97
> > B? 97
> >
> > R=0x1E G=0x1E B=0x1F
> >
> > Enter values, 'q' to quit
> > R? q
> > Done.
> >
> > $ ./lcms2131/bin/transicc -c1 -s -ex -i profile.icc -b -t1
> > LittleCMS ColorSpace conversion calculator - 5.0 [LittleCMS 2.13]
> > Copyright (c) 1998-2022 Marti Maria Saguer. See COPYING file for
> > details.
> >
> > Enter values, 'q' to quit
> > R? 97
> > G? 97
> > B? 97
> >
> > R=0x9F G=0x9F B=0x9F
> >
> > Enter values, 'q' to quit
> > R? q
> > Done.
> >
> > I also built 2.12 and 2.13.1 on Windows, using the provided VC 2019
> > project files (default config - win32 debug), and got the exact same
> > results.
> >
> > I have no idea why we're seeing different behavior with transicc
> > 2.12. I can't think of anything that would explain that. I ran
> > both versions under valgrind on Linux, and it didn't report any
> > errors.
> >
> > One other note: I believe the 0x1e results are correct. I
> > discovered this odd behavior looking at a regression test on my
> > Xpdf build. The 2.12 output (0x1e) matches the output I see from
> > Adobe.
> >
> > I'll be happy to do more testing, if there's anything that you think
> > might help track this down.
> >
> > - Derek
> >
> >
> >> LittleCMS ColorSpace conversion calculator - 5.0 [LittleCMS 2.12]
> >> Copyright (c) 1998-2020 Marti Maria Saguer. See COPYING file for
> >> details.
> >>
> >> Enter values, 'q' to quit
> >> R? 97
> >> G? 97
> >> B? 97
> >>
> >> R=0x9F G=0x9F B=0x9F
> >>
> >> Enter values, 'q' to quit
> >> R? q
> >> Done.
> >> marti@debian:~$ transicc -c1 -s -ex -i profile.icc -b -t1
> >> LittleCMS ColorSpace conversion calculator - 5.0 [LittleCMS 2.13]
> >> Copyright (c) 1998-2022 Marti Maria Saguer. See COPYING file for
> >> details.
> >>
> >> Enter values, 'q' to quit
> >> R? 97
> >> G? 97
> >> B? 97
> >>
> >> R=0x9F G=0x9F B=0x9F
> >>
> >> Enter values, 'q' to quit
> >> R? q
> >> Done.
> >>
> >> Should I use your exact program to reproduce the issue? The
> >> transicc utility does basically same.
> >>
> >> BTW I have checked ColorSync utility on relcol to sRGB. ColorSync
> >> does not have black point compensation, but turning it off on both
> >> sides, they agree on same value: 30
> >>
> >> Regards
> >> Marti
> >>
> >>
> >>
> >> > The input profile is from a PDF file, and claims to be e-sRGB.
> >> > With INTENT_RELATIVE_COLORIMETRIC and
> >> > cmsFLAGS_BLACKPOINTCOMPENSATION, the transform to sRGB (builtin
> >> > profile) produces completely different results.
> >> >
> >> > The code looks like this (error checking and cleanup
> >> > intentionally omitted):
> >> >
> >> > #include <stdio.h>
> >> > #include <lcms2.h>
> >> >
> >> > int main() {
> >> > cmsHPROFILE inputProfile = cmsOpenProfileFromFile("profile.icc",
> >> > "r"); cmsHPROFILE outputProfile = cmsCreate_sRGBProfile();
> >> > cmsHTRANSFORM xform = cmsCreateTransform(inputProfile,
> >> > TYPE_RGB_8, outputProfile,
> >> > TYPE_RGB_8, INTENT_RELATIVE_COLORIMETRIC,
> >> > cmsFLAGS_BLACKPOINTCOMPENSATION);
> >> > unsigned char in[3] = {0x61, 0x61, 0x61};
> >> > unsigned char out[3];
> >> > cmsDoTransform(xform, in, out, 1);
> >> > printf("%02x %02x %02x\n", out[0], out[1], out[2]);
> >> > }
> >> >
> >> > and I'm attaching the profile.
> >> >
> >> > The results with 2.12 are "1e 1e 1e" and with 2.13 (same with
> >> > 2.13.1) are "9f 9f 9f".
> >> >
> >> > I pulled the profile out of a PDF file, so it's possible there's
> >> > a problem in the profile itself -- but I'm not seeing any error
> >> > messages from LCMS if I use cmsSetLogErrorHandler.
> >> >
> >> > If anyone has some idea of what's going on here, I'd love to
> >> > know.
> >> >
> >> > Thanks!
> >> > <profile.icc>_______________________________________________
> >> > Lcms-user mailing list
> >> > Lcm...@li...
> >> > https://lists.sourceforge.net/lists/listinfo/lcms-user
> >>
> >
> >
> >
> > _______________________________________________
> > Lcms-user mailing list
> > Lcm...@li...
> > https://lists.sourceforge.net/lists/listinfo/lcms-user
>
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