Re: [PATCH] [For-Review] CMYK profile gamut support

[Richard Hughes <hughsient gmail com>]

On 17 October 2011 20:30, James Cloos <cloos jhcloos com> wrote:
> Here is an intial proof-of-concept patch.  I still need to update
> gcm_cie_widget_draw_line() for cmyk and to split it into a sequence
> of commits, but the hexagon hull of the gamut is drawn.

Yup looks good. I'm wondering if it's actually useful to do the
gcm_cie_widget_constrain_rgb() thing, no other CIE diagrams on the web
seem to bother.

> My tests show that the r-y-g-c-b-m hexagon is only an approximation of
> the profile’s gamut, but it is a reasonable one.  *Very* few colours
> escape the hexagon, and only just barely.

Yes, it looks good indeed.

> A spherical polygon may be more accurate than a planar polygon, but
> converting the edges of a spheroid hexagon into planar cubic curve_to
> calls is more complex than this probably needs to be.

For the purposes of gcm-viewer, i think that's fine. Small nits about
your patch:

-       if (cie->priv->colorspace == CD_COLORSPACE_CMYK ||
cie->priv->colorspace == CD_COLORSPACE_CMY)
+       if (cie->priv->colorspace == CD_COLORSPACE_CMYK ||
+           cie->priv->colorspace == CD_COLORSPACE_CMY)

-       if (cmyk)
-       {
+       if (cmyk) {

The tab alignment in gcm-profile.h is a little off.

Other than that, I like it. Thanks!

Richard