[cairo] Spot colors (and CMYK)

Kai-Uwe Behrmann ku.b at gmx.de
Sat Feb 20 00:59:41 PST 2010

Am 19.02.10, 18:13 +0100 schrieb ecir hana:
> On Thu, Feb 18, 2010 at 5:45 PM, Kai-Uwe Behrmann <ku.b at gmx.de> wrote:
>> Am 18.02.10, 17:21 +0100 schrieb ecir hana:
>>> - What would happen if I don't provide a hook to Cairo? What will
>> That would mean using the color toy API and no direct colour management.
>>> happen if I wan to draw CMYK on RGB surface and I wont provide a hook?
>> It would not work. Your application has to link to the hook lib and its CMS.
> That's the problem. Because a hook requires a profiles and a profile
> might not be available. So if I want to use some Pantone I don't have
> profile for I should be able to type in some values manually, so at
> least something appears or the screen preview.

What to do without fonts and render text? Isnt that stuff up to the 
application level? I doubt that cairo shold take care of fonts, ICC 
profiles and such to be properly installed.

>>> Or more common, I have Pantone duotone and want to look at it? I guess
>>> there should be some really basic, toy, hook by default, no? But that
>>> would be the start of Cairo's own CMS, no?
>> Thats up to cairo maintainers. Once a hook API is decided for, I guess they
>> prefere less dependencies. Mosularity is sometimes really nice.
> What I meant was, that if there are always required profiles, there
> should be a way of building a very simple profile which would take
> care of the most basic and crude transformations. Alternatively, by
> supplying a LUT (instead of a profile) you could immediately export
> this LUT to PDF as tintTransform.

Cairo should not be required to build profiles in the first place. Please 
see above.

However, on application or CMS level there are several ways to create 
profiles on the fly or package them with the app.

Mit freundlichen Grüßen
Kai-Uwe Behrmann
Programmierung für Farbmanagement
www.behrmann.name + www.oyranos.org

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