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

[Boudewijn R. <bo...@va...>]

Would it be technically possible to create another icc profile that does some pre- or post-correction to work around this profile's bugs? It seems it's pretty widely used and recommended, for some weird reason.

On zaterdag 7 december 2019 21:49:10 CET Mar...@li... wrote:
> 
> 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
> 
> 
> 
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