[cairo] Color, Cairo and Cups

[Billy Biggs]

Larry Ewing (lewing at gnome.org):

> On Wed, 2006-03-08 at 18:13 -0500, Behdad Esfahbod wrote:
> > On Wed, 8 Mar 2006, Larry Ewing wrote:
> > 
> > > Additionally if you ignore gamma (which Cairo does anyway
> > > right?) the working space doesn't matter too much for many
> > > operations.
> > 
> > It does matter for any operation involving color blending, like
> > all operations with non-opaque alpha, and all with antialiasing
> > on.
> 
> To clarify I was talking mainly about other RGB spaces here, not wildy
> different ones.

  The problem is that Cairo currently deals with sRGB (gamma-corrected)
values, and compositing in a gamma-corrected colour space is wrong
and leads to artifacts.  This problem is known but fixing it is hard
(read: slow, and most other software also gets it wrong).

  -Billy