[Development] QT5 and color management

Allan Sandfeld Jensen kde at carewolf.com
Tue Aug 30 22:11:13 CEST 2016


On Tuesday 30 August 2016, Morten Sorvig wrote:
> One remaining issue (after the platform plumbing has been done) may be
> that QPainter and the raster paint engine assumes a linear color space
> when blending. As I understand it OpenGL solves this by converting
> sRGB framebuffer values to linear color for the blending step.
> 
I have looked into that previously. It is mainly blocked by uncertain scope, 
what color-spaces should be supported, and should they be tied to QImage, 
QScreen, QGuiApplicaiton, QColor or all of the above? I also postponed adding 
support for RGB64 QImage formats until I figured out how gamma-correction 
should be handled.

If we have a specific scope I can adjust my proto-type and suggest an 
implementation.

Also I ran into the problem that gamma-corrected 2D anti-aliasing subjectively 
looks bad/wrong, probably because naive blending is closer to human 
perception, though it is less physically accurate (most screens gamma-curves 
are designed to fit human perception of brightness). Which raises the question 
if gamma-corrected blending is even worth the effort outside of photo 
realistic looking 3D rendering.

`Allan





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