#Gamma values !?
5 messages in this thread
I want to make a picture that is built out of 1×1 pixel black and white
checker, and put out several halfway gray (128,128,128) boxes on it. These
boxes should be gamma corrected individually. They gammas should be from 0.8 to
2.5, with a step of 0.1. This picture I will use to calibrate what gamma
settings to use for different paper and slide output.
If you, or someone else, could give me the gamma correction algoritm
(preferably i C-code), or just give me the right gammacorrected gray value
for(0.8,0.9,1.0, ….,2.4,2.5), it would really help.
-M.E
The basic gamma correction function is an exponential function of the form:
lookup value = intensity (to the power) 1.0/y
Where (y) is gamma, and it represents the nonlinearity
of the monitor.
If you want to see a simple lookup table of monitor values, check out the
readme.doc that ships with R3.
If you need more information about gamma, pick up a copy of "Illumination and
Color in Computer Generated Imagery" by Roy Hall (published by Springer Verlag
press).
– G
>The basic gamma correction function is an exponential function of the form:
>lookup value = intensity (to the power) 1.0/y
So if I want the gamma corrected intensity of medium gray (128,128,128) at
gamma 2.2 I would solve the following :
128 = X (to the power) 1.0/2.2
Have I got it the wrong way, or is this right?
-M.E
That ought to do it.
– G
Thanks!
-M.E