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

On Thu, Sep 12, 2013 at 2:55 PM, Tab Atkins Jr. <jackalmage@gmail.com>wrote:

> On Thu, Sep 12, 2013 at 1:37 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> > On Thu, Sep 12, 2013 at 12:54 PM, Simon Sapin <simon.sapin@exyr.org>
> wrote:
> >> Maybe, but that’s different from the feature specified in GCPM (and that
> >> we just decided to move into Color) which does *device* CMYK, where the
> >> profile is intentionally unspecified.
> >
> > Sure, but if you're showing it on screen, you have to convert it to RGB
> as
> > some point.
> > What is the profile for that conversion?
>
> An unspecified, device-dependent profile.


ok, in that case it might be best to do the simple conversion to RGB:

red = 1.0 - min(1.0, cyan + black)
green = 1.0 - min(1.0, magenta + black)
blue = 1.0 - min(1.0, yellow + black)


Doing the reverse during printing, you know both profiles so you can do an
ICC conversion. We probably want to special case rgb(0,0,0) though since
everyone wants that to be 100% black.