The color.gamma texture property is linked to the color and color_alpha texture property. it defines the gamma correction applied to the color and color_alpha texture property. Monitors using the sRGB color space have roughly a gamma of 2.2 . Images autored on monitors thus usually have also an sRGB color space and thus also a gamma of 2.2 . To allow Graphic Modules to render in linear color space the gamma has to be known that the images assigned to the color and color_alpha texture property use. In most cases you do not have to touch this texture property. If you use though linear space images or high definition range images then you have to set the gamma to 1 to avoid gamma correction. Other situations might exist if an image has a different gamma correction to better use the 8-bit resolution. This might be of use for very bright or dark images.
The value is typically a 1 component value larger than 0.
The default value for this texture property is 2.2 which is roughly sRGB gamma correction.
( TODO: example image )