CalibrateMonitorPhotometer

Psychtoolbox › PsychCal

[gammaTable1, gammaTable2, displayRange. displayGamma] =
A simple calibration script for analog photometers. numMeasures (default: 9)
readings are taken manually, and the readings are fit with a gamma function
and piecewise cubic splines. numMeasures - 1 should be a power of 2, ideally (9, 17, 33, etc.).
The corresponding linearized gamma tables (1 -> gamma,
2 -> splines) are returned, as well as the display baseline, display range in cd/m^2 and
display gamma. Plots of the two fits are created as well. Requires fit
tools.

If the normalized gamma table is not loaded, then the cd/m^2 value of a
screen value can be figured out by the formula: cdm2 =
displayRange*(screenval/255).^(1/displayGamma) + displayBaseline.

Generally, you will want to load the normalized gamma tables and use them
in Screen('LoadNormalizedGammaTable'). For example:

[gammaTable1, gammaTable2] = CalibrateMonitorPhotometer;
%Look at the outputted graphs to see which one gives a better fit
%Then save the corresponding gamma table for later use
gammaTable = gammaTable1;
save MyGammaTable gammaTable

%Then when you're ready to use the gamma table:
load MyGammaTable
Screen('LoadNormalizedGammaTable', win, gammaTable*[1 1 1]);


History:
Version 1.0: Patrick Mineault (patrick.mineault@gmail.com)
22.10.2010 mk Switch numeric input from use of input() to use of