Re: [Lcms-user] Gamut Warning

[Gerhard F. <nos...@gm...>]

T E Schmitz schrieb:

> Gerhard, Marti, thank you for all your replies.
>
>> Humm... well, primary goal of gamut check are output profiles. It 
>> would be quite difficult to use it on input profiles, since there are 
>> no out of gamut colors in input direction.  
>
> I have the impression that we have a misunderstanding - please correct 
> me if I'm picking up the wrong end of the stick here:
>
> I don't think I was gamut checking the input profiles but the 
> conversion to working space profiles. I tagged the scanned image with 
> an input profile and then I gamut checked it against Adobe1998, ie a 
> monitor profile.
>
> Gerhard mentioned BToA tables. I presume they are normally found in 
> output profiles?

Hi Tarlika,

according to the ICC spec, BToA tables (PCS -> device space 
transformation) may be present in Input, Display, Output and Colorspace 
profiles (though It is probably questionable, whether they make too much 
sense for the normal use case of input profiles). Alternatively, Input 
and Display profiles can also be matrix/shaper profiles (without AToB or 
BToA tables), and Adobe1998 belongs to the latter class. For a 
matrix/shaper profile, usually out-of-gamut is assumed for all colors, 
which would map to either negative RGB values or to RGB > 255, since 
such RGB values are not realizable on a monitor.

Best Regards,
Gerhard