Re: [Lcms-user] odd change in 2.13

[Derek B. N. <de...@gl...>]

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>_______________________________________________
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