[Openicc] CUPS Color Management under Linux... (what is to do ?)

[Chris Murphy]

On Feb 10, 2011, at 12:17 PM, Leonard Rosenthol wrote:

> On Thu, Feb 10, 2011 at 2:03 PM, Chris Murphy <lists at colorremedies.com> wrote:
> As I think about it, the most reliable "no color management" tag is a message directly to the thing that does the conversions. And that's the CMM. So the message would be a particular kind of ICC profile.
> 
> Of course we'd be best off getting such a profile endorsed by the ICC, but I don't know that's necessary. If we get lcms on board, that's 1/2 the battle right there since it seems our focus for a color managed print pipeline right now is CUPS+GhostScript+lcms. We know ICC profiles are passing through all the way to the CMM or we wouldn't get conversions (assumed or otherwise), so this makes some sense.
> 
> 
> If you mean a "null" profile (or null transform), there is already a concept of that in ICC...

There is a concept of null transform, but it requires the source and destination profiles be explicitly set to the same profile (the metric for determining this can be complex because it's not reliable to just use filename, and ICC v2 didn't use md5, etc.)

If there is a null profile, I have never heard of such a thing.



> 
>  
> My preference is that this ICC profile would be a header only profile, no body, and class 'spac' (ColorSpace Conversion) to differentiate it and hopefully avoid it being obviously useable and embeddable like very common 'mntr' (display device) class, and 'prtr' (output device profile) class profiles are. I'm not sure what the PDF spec thinks about 'spac' class profiles however...could be a sticking point.
> 
> 
> PDFs can only use mntr & prtr profiles.

That's not good. So the new ICC v4 sRGB profile cannot be used in PDF at all? That is a 'spac' class profile.

And even Lab images have a profile in them, and they are supposed to be 'spac' because there isn't just one kind of L*a*b* encoding. What we typically use is D50 L*a*b* but there are others (rare) floating about.


Chris Murphy
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