gamma

I want to implement gamma correction to my OpenGL lighting, but with gamma correction applied, my results do not seem linear at all. I also found OpenGL: Gamma corrected image doesn't appear linear which is very similar to my issue, but hasn't yet received an answer nor discussed actual diffuse lights. As an illustration, I have the following 4 light colors defined in linear space: glm::vec3 lightColors[] = { glm::vec3(0.25), glm::vec3(0.50), glm::vec3(0.75), glm::vec3(1.00) }; With each light source seperated and a basic linear attenuation applied to a diffuse lighting equation I get the

I am working on a face recognition project. I have pictures with different lighting so I need to do illumination normalization. I read a paper which which claims to do illumination normalization. The paper describe the following function and values. 1- gamma correction with gamma = 0.2 2- Difference of Gaussian (DOG) filtering with (sigma0 = 1, sigma1 =2) 3- contrast equalization (truncation threshold of 10 and compressive component 0.1 is used in the paper) I use CvPow for gamma correction, CvSmooth for DoG and Threshold() with truncate (I don't know how to specify the compression component)

Color space . Well, everybody knows about RGB: three values normalized in the range [0.0,1.0], which have the meaning of the intensity of the color components Red Green Blue; this intensity is meant as linear, isn't? Gamma . As far I can understand, gamma is a function which maps RGB color components to another value. Googling on this, I've seen linear functions and non linear functions... Linear functions seems to scale RGB components, so it seems to tune image brightness; non linear functions seems to "decompress" darker/lighter components. Now, I'm starting to implement an image viewer,

Does anyone know how I can achieve the following effect in OpenGL: Change the brightness of the rendered scene Or implementing a Gamma setting in OpenGL I have tried by changing the ambient parameter of the light and the type of light (directional and omnidirectional) but the result was not uniform. TIA. Thanks for your help, some additional information: * I can't use any windows specifics API. * The gamma setting should not affect the whole window as I must have different gamma for different views. On win32 you can use SetDeviceGammaRamp to adjust the overall brightness / gamma. However, this