Re: [Groff] Re: CMYK <-> RGB

[Ralph Corderoy]

Hi,

>       r = 1 - c + ck - k
>       r = (1 - c)(1 - k)

Sorry to take this off-topic, but why is the `+ ck' there?  Why isn't
it

    r = 1 - c - k

on the basis of cmy to cmyk is

    k = min(c, m, y)
    c, m, y = c - k, m - k, y - k

so cmyk to cmy is

    c, m, y = c + k, m + k, y + k

and cmy to rgb is

    r, g, b = 1 - c, 1 - m, 1 - y

I'm obviously wrong on this but can't see why at the moment.


Ralph.