[cairo] Spot colors (and CMYK)

ecir hana ecir.hana at gmail.com
Wed Feb 17 13:19:27 PST 2010

On Wed, Feb 17, 2010 at 8:31 PM, Chris Murphy <lists at colorremedies.com> wrote:
>> 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?
> Seems to me if there is no compositing being performed, any CMYK object (tagged or untagged) could simply be passed through, along with color space metadata. However, if any compositing is being done between objects of different spaces, they do need to be normalized first to a common color space. Ignoring the color space of either object is a kind of data loss.

Yes, ok, no problem. Who should normalize to the common space and how?
Or you could simply disallow compositing over different spaces and let
the application do the hard work. I guess we repeat ourselves....

> This is a PDF/X-3/4/5 vs PDF/X-1a kind of workflow. One is early binding (everything is CMYK, nothing is to be repurposed/converted except for soft and hard proofing purposes, where you DO NOT WANT 40,30,30,100), that's PDF/X-1a. And the other is late binding which means predominantly ICCBased objects, all of which are converted when you get to the output stage and have a better idea where the job will print.

I don't understand why you said "DO NOT WANT" - I thoguht, for X-1a it
should read "DO WANT". But yes, this is exactly X-1a vs higher specs.

> Saying you want specific CMYK values means you know exactly what printing behavior you're targeting including the media and ink set. CMYK values are control signals. They only translate into color when the device is known/defined.

And I know them. Because my app told me.

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