- Gamma
Gamma is a type of transfer function (simple power law).
Gamma is an older extension that can be used in conjunction with an nclc extension. The nclc transfer function must be set to 2 = "unknown".
The standard nclc gamma is close to 2.0 on a computer screen (QuickTime display) and 2.2 (sRGB) on TV.
Setting gamma to a higher value makes the movie darker on the computer screen.
Some older QuickTime movies have gamma 1.8.- Nclc
nclc is an extension consisting of primaries, transferFunction and matrix.
primaries are the primary RGB colors (corner points of the RGB chroma triangle) used for RGB encoding.
transferFunction is the transformation applied to linear light values to make them "perceptually uniform".
matrix are the coefficients used for converting RGB to YCbCr.
Currently the official values for nclc are limited as follows:
primaries 1-5-6-9 (HD, PAL, NTSC, UltraHD)
transferFunction 1-14-15 (rec.709, UltraHD 10 bit, UltraHD 12 bit)
matrix 1-6-9-10 (HD, PAL/NTSC, non-constant luma UltraHD, constant luma UltraHD).
In addition the value 2 means "unknown".