[cairo] Color, Cairo and Cups

[Russell Shaw]

Billy Biggs wrote:
> 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).

It's really insane to make the data non-linear for anything other than
at the final output to a display device, or to linearize the input from
an input device.