On Saturday 06 December 2008 14:55:20 Graeme Gill wrote: > Peter Karp wrote: > > Are you aware of programs which measure gamma different then as > > simplified gamma function? I think that none of the usual solutions to > > calibrate a monitor will use a GOG or further model. > > As I understand it, there is certainly software out there that > will do various least squares fits to get a gamma number > (Gernot Hoffmann for one, if my memory is correct). LCMS has a function that will give an estimated gamma from a set of values in a gamma table. I have not tried this but from a series of measurements it should be possible to put the scaled L* values of those measurements into a gamma table and use the cmsEstimateGammaEx() function to get a good estimate of the actual gamma of a device. This might not give better results for devices that are well behaved (like most CRTs) but might do better for devices that are not as well behaved (like some LCDs). I have not looked at the code in this function to see what algorithm it uses. > > The gamma measure used in the Argyll utilities is a simple > 50% measure ("what pure gamma/exponent value will give the same response > relative to white at 50% input, as the actual response curve"). > This measure is fast to measure, simple to compute, independent of > the black point treatment and exact curve shape, and corresponds well > to the overall look of the response curve. > > Graeme Gill.