brightness&contrast

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1 comment, last by Vladimir 23 years, 5 months ago
How to change brightness and contrast? I use opengl and I tried: glPixelTransferf(GL_XXX_BIAS, ...); glPixelTransferf(GL_XXX_SCALE, ...); but it works not very good and different in different cases. I think contrast and brightness is not opengl specific question. How to change it? (on geforce for example) How it''s done in Quake3? vladimir
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//this is a part of a similar thread on Opengl.org,the answer posted here is from Bob:

There is no (as far as I know) OpenGL-function to boost brightness. But you can do it yourself if you want to, by calling all color-functions like this.
glColor3f(red*bright, green*bright, blue*bright)

... where bright is the brighness you want. 0=black, 1=standard color, 2=twice as bright and so on.

There is also a function in Win32 called SetDeviceGammaRamp, haven''t tried it but you can look in the documentation.
//End of post

P.s.:Don´t know how q3 adjusts the brightness,but I think it uses the first method,´cause it passes colors for every vertex anyway.For the complete thread go here:
http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/000452.html


HTH,XBTC!
I emailed John Carmack about this.. I believe in Q3A he used SetDeviceGammaRamp

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