Gama... trying to understand Gama

So I was doing some light reading on Gama over colors and if I understand correctly it is just a logarithmic compression of color space used? and it goes back and forth considering the hardware used to display as you compress and decompress it?

Basically, but Gamma is a power function, not a logarithm.
It is roughly modeled after human vision, which is not linear (you’d have serious issues in every day life if it was), so encoding the dynamic range of a monitor with only 8 bits/channel would give poor quality, hence the Gamma encoding.

But nowadays you’re hardly ever using a “true” Gamma function, sRGB uses a hybrid function of a linear segment followed by a Gamma 2.4 curve. Reason is that a pure gamma function has zero slope at origin and hence gives issues with inversion. Can be approximated with a Gamma 2.2 curve, but you can see a slight deviation in the darker areas.

Then there’s HDR encodings that use other curves.
Rec. 2100 defines two sets:

Hybrid Log-Gamma extends the Gamma curve with a logarithmic segment, that way a 10 or 12-bit HDR encoding can easily be converted to 8-bit SDR without quality loss in the supported signal range.

The other one is called Perceptual Quantizer and basically models human vision more precisely for a wider dynamic range than the simple Gamma function.

2 Likes

Yes power. It is quite a bit to take in. I have been finding gamma a topic a bit odd to wrap my head around as it is display subjective or something.

I need to search some more stuff that you spoke of there.

I have been thinking in making a gama slider but the more I read the more weird the use it sounds. As to how to use it too.