>Psychtoolbox>PsychCal

cal = CalibrateFitGamma(cal,[nInputLevels])

Fit the gamma function to the calibration measurements. Options for field
cal.describe.gamma.fitType are:
simplePower
crtLinear
crtPolyLinear
crtGamma
crtSumPow
betacdf
sigmoid
weibull

Underlying fit routine is FitGamma for functional forms originally supported,
and these rely on the optimization toolbox.

Newer functions (e.g, crtSumPow, betacdf) use the curvefit toolbox and that’s just
done locally in this routine. Much less cumbersome.

NOTE (5/27/10, dhb): crtSumPow does not currently appear to normalize the
measurements to unity, while the older methods do (in FitDeviceGamma)).
This may be a bug, but since we’re not currently using crtSumPow I’m not
going to look into it in detail right now.

See also PsychGamma.

3/26/02 dhb Pulled out of CalibrateMonDrvr.
11/14/06 dhb Define nInputLevels and pass to underlying fit routine.
07/22/07 dhb Add simplePower fitType.
08/02/07 dhb Optional pass of nInputLevels.
dhb Don’t allow a long string of zeros at the start.
dhb Reduce redundant code for higher order terms by pulling out of switch
08/03/07 dhb Debug. Add call to MakeMonotonic for first three components.
11/19/09 dhb Added crtSumPow option, coded to [0-1] world and using curve fit toolbox.
3/07/10 dhb Cosmetic to make m-lint happier, including some “|” -> “||”
3/07/10 dhb Added crtLinear option.
dhb contrasthThresh and fitBreakThresh values only set if not already in struct.
dhb Call MakeGammaMonotonic rather than MakeMonotonic where appropriate.
dhb Use linear interpolation for higher order linear model weights, rather than
a polynomial. I now think that ringing is worse than not smoothing enough.
3/08/10 dhb Update list of options in comment above.
5/26/10 dhb Allow gamma input values to be either a single column or a matrix with same number of columns as devices.
6/5/10 dhb Extend fix above to higher order terms in the gamma fit.
dhb Fix or supress MATLAB lint warnings.
dhb Add betacdf fit option, which seems to provide a flexible sigmoidally shaped fit.
6/8/10 dhb, ar Make sure to set cal.gammaInput in options that use curvefit toolbox method.
Add a call to MakeGammaMonotonic around input values for higher order linmod fit.
6/1010 dhb Fix higher order fit in case where there are multiple gamma input columns. Blew this the other day.
6/11/10 dhb Allow passing of weighting parameter as part of cal.describe.gamma structure. Change functional form of betacdf
to include wrapped power functions.
4/12/11 dhb For simplePower option, return vector of exponents in cal.describe.exponents.