The quote below is from an article publicised on the Siggraph.org website. Although it is a bit technical, I find this explanation helpful so I am including the quote here for future reference: “Since we know the relationship between the voltage sent to the monitor and the intensity which it produces, we can correct the signal before it gets to the monitor. The signal is adjusted so that it is essentially the complement of the curve shown above. Note that the task of gamma correction is accomplished by raising the input value to the 1/2.5 power. This is referred to as a gamma correction of 2.5; because we are correcting the input for a monitor whose gamma is 2.5” (extract from http://www.siggraph.org/education/materials/HyperGraph/color/gamma_correction/gamma_intro.html)
http://www.siggraph.org/education/materials/HyperGraph/color/gamma_correction/gamma_intro.html - this is a shorter piece that makes an effort to explain in simple terms how gamma corrections are used and why.
http://ftp2.bmtmicro.com/dlc/Color%20Management.pdf - a guide to colour management. I found it a bit technical but it could be a useful reference.
