Re: [css-gcpm][css-color] device-cmyk() interaction with RGB-space colors.

On Wed, Sep 25, 2013 at 4:20 AM, Chris Lilley <chris@w3.org> wrote:

> Hello Tab,
>
> Tuesday, September 24, 2013, 11:22:32 PM, you wrote:
>
> > Compositing and blending are both defined in terms of RGB colors.
>
> Yes, currently.
>

Not in the CSS blending spec.


>
> > If you think it can be done in CMYK space, that's cool, but it needs
> > to be defined,
>
> it can't, not directly.
>

What "can't"? Can we not composite in CMYK, or can we not define it?


>
> >  and we still need to define a sane behavior for handling
> > mixtures of RGB and CMYK colors.
>
> Your mention of 'sane' make me believe you think this needs to be
> invented on the fly by this WG. It doesn't.
>
> It certainly needs to be documented, but how to do it is already
> established and already implemented a bunch of times so we just need
> to summarise how that is done, and point off to other specifications
> for further details.
>
> I mentioned this at the f2f (the keywords being 'profile connection
> space' and an extension to the color-interpolation property to add
> Lab).


Lab interpolation seems only needed for gradients so maybe it's easier to
special case that as opposed to taking a blunt property like
'color-interpolation'