Re: [Lcms-user] [SPAM] Re: Bug in soft proofing?

[<Mar...@li...>]

Quoting Wolthera <gri...@gm...>:

> Hey,
>
> So, the person who made that bugreport, David Revoy, has tried to use
> the profile because the printing company requested it of him, with
> terrible results:
> https://www.davidrevoy.com/article747/the-english-book-printed-project-production-report-2#c0747-1890
>
> So, what is going on here that even though the profile is borked,
> indesign is showing a proper proof(perhaps due to using a different
> table? Bizare that photoshop then acts weirdly...).

In the thread you mention, there are other people that found the  
profile to be buggy in photoshop. So, I have further investigated this  
profile, and found the source of problems on the B2A1 table, that is,  
the relative colorimetric proofing direction. It is broken. It seems  
to me that it is implementing some sort of absolute colorimetric,  
which would be emulating the paper white. Some products of Adobe "hot  
fixes" this profile, when used as softproof, but this is just hidding  
the profile error, which is something that lcms does not.

You can also try the icc profile inspector available in the ICC site  
(www.color.org) If you take a look on the rel.col table (B2A1), the  
output curves seems a little bit off when compared with the perceptual  
table (B2A0) which is correct.

> And that in turn affects users because they just cannot follow the
> printing company's instructions faithfully: everything looks weird in
> LCMS running software. Is there something we can do to smooth this
> out?

I would try to either to found another profile that represenst the  
standard, or to build one by using argyll and the measurement set  
available on ICC site. See below:

http://www.argyllcms.com
http://www.npes.org/Portals/0/standards/docs/CGATS21-2-CRPC1.txt


Regards
Marti Maria