[cairo] Spot colors (and CMYK)

[ecir hana]

On Wed, Feb 17, 2010 at 7:17 AM, Bill Spitzak <spitzak at gmail.com> wrote:
>
>
> ecir hana wrote:
>>
>> I have a picture in CMYK (SWOP ICC), that's "deviceA". I want to
>> preview it on screen, *application* converts it to sRGB and sends this
>> 3D data to Cairo. Then, Cairo converts it to the space of my monitor
>> ("deviceB") and draws it.
>>
>> It looks ok, so I want to export PDF - *application* converts my
>> picture to sRGB and Cairo converts it back to SWOP CMYK (because I
>> print in US on coated paper).
>>
>> Is this what you said?
>
> Yes.
>
> If you really want to control the CMYK on the output device you have to use
> a device-specific api.

Yes, I really want to control the CMYK, such API is the topic of this thread.

If I say CMYK(40, 30, 30, 100) I want CMYK(40, 30, 30, 100). I bet you
understand what I'm talking about - it's the same as reading Quicktime
and writing it back as Quicktime, as you wrote above - going from CMYK
to sRGB and back to CMYK makes no sense.

Again, the real question is, how do you supply CMYK image to Cairo and
first, show it on the screen and second, export it to PDF with the
same set of graphic operators?