Open GL : Changing Brightness and Contrast of the Image

I have one module to implement in which I have to change the Brightness and Contrast of the Image for IPhone.

After ref 开发者_如何学JAVAsome samples like GLImageProcessing , seems need to go with Open GL (In this sample, we can able to do one activity at a time either brightness or contrast), As I am new to this Open GL and not able to work out with this.

Kindly provide me some threads or ref regarding same ,it will be helpful to move in right direction.

thanks, Sagar

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Try google: glPixelTransferf and GL_RED_SCALE Here's some ref: http://pyopengl.sourceforge.net/documentation/manual/glPixelTransfer.3G.html