kPsychEnableSRGBRendering - aleslab/Psychtoolbox-3-aleslab-fork GitHub Wiki

rval = kPsychEnableSRGBRendering

Return a flag that you can pass to the 'imagingmode' parameter of
Screen('OpenWindow'). If this kPsychEnableSRGBRendering flag is
given then rendering to the framebuffer will happen in sRGB format
if the target framebuffer supports this, ie. is in sRGB color buffer
format.

The sRGB color space is based on typical (non-linear) monitor
characteristics expected in a dimly lit office. It has been
standardized by the International Electrotechnical Commission (IEC)
as IEC 61966-2-1. The sRGB color space roughly corresponds to 2.2
gamma correction.

https://www.khronos.org/registry/[OpenGL](OpenGL)/extensions/ARB/ARB\_framebuffer\_sRGB.txt

In general, only RGBA8 framebuffer formats are sRGB capable, as
typical GPU's do not implement sRGB on other formats, and for
floating point framebuffers, sRGB encoding would be pointless,
as they provide already a non-linear format with much more precision,
so no need for sRGB style compression.

Given that Screen() does not explicitely request sRGB system framebuffers,
this flag will only apply to output (sink) FBO's when the imaging pipeline
is active, and there only if an external sink texture is passed in by some
external client, ie. the kPsychUseExternalSinkTextures flag is given as well.

The only known potential client of this is currently the Oculus VR runtime
compositor, which wants to process sRGB RGBA8 textures as input, unless you
choose half-float textures.