Editing Chroma subsampling (section)

====Regarding gamma and transfer functions====
Gamma encoded luma <math>Y'</math> should not be confused with linear [[Relative luminance|luminance]] <math>Y</math>. The presence of gamma encoding is denoted with the [[prime symbol]] <math>'</math>.

Gamma-correcting electro-optical transfer functions (EOTF) are used due to the nonlinear response of human vision. The use of gamma improves perceived signal-to-noise in analogue systems, and allows for more efficient data encoding in digital systems. This encoding uses more levels for darker colors than for lighter ones, accommodating human vision sensitivity.<ref name=plea>Poynton, Charles. [http://www.poynton.com/PDFs/YUV_and_luminance_harmful.pdf "YUV and ''luminance'' considered harmful: A plea for precise terminology in video"].</ref>