[my note]about gamma correction

Correct terminology: 

1. Gamma, usually is 2.5 from CRT device because of lighting by voltage.  LCD display has different gamma value, Besides, display device are not limited by gamma 2.5. However, new display still made with a gamma value. ex. Apple display is 1.8. 

2. In human vision aspect,  LMS cones have a non-linear response function.  In dark, L = L^0.4; In bright, L = L^0.5;  this response curve have no direct relationship with Gamma in display.  they look alike,  it is coincidence. 

3.  Gamma correction in Camera. Our eyes do not perceive light the way cameras do.

To make the image which captured from radiance close to eye perception,  add a gamma 2.2 which based on sRGB.(most of display device use sRGB). 

4.  

Credit to : http://www.cambridgeincolour.com/tutorials/gamma-correction.htm