Cairo don't support colors out of bound

In color editor dialog page … examples show out of bound color result .

This don’t work as expected with cairo render
RGB 200-0-0 = RGB 100-0-0 (with cairo render on workarea)

Is this kind of issue already reported on buggenie ?


It is something that is known and won’t fix. Cairo is ARGB32 (8 bits per channel) and Synfig is RGBA128 (32 bits per channel).

Cairo admits color channels as float point values between 0.0 and 1.0 (that finally is mapped to a 0-255 unsigned value), anything outside that is clamped by Cairo API. That’s why it won’t never be fixed unless Cairo library implements 32 bits per channel.


humm… yep understand

i have added a note on wiki

So, even if synfig rendering core is more than ten years old he is kind of more powerful than recent lib ??? at least for color management…
and synfig must keep his own core to render video… is’nt it ?


I know that I have to learn to report bugs properly but I will report this here.

Cairo render do have a problem! It doesn’t take in account the gamma panel of the Setup window. Go to File=>Setup then Gamma panel. If you set R,G and B to 2.3 it will be the same.

I do not understand why the 2.3 must be in the source as it is the Gamma value.

P.S. I haven’t looked to the source recently. I just remember the a strange 2.3 or something…

It is 2.2 and it is currently fixed at master branch.
Read here to understand more about gamma and why 2.2.