To use this simulator, you will need two things:
This page takes you through the nuts and bolts of the
simulation. It also assumes some basic familarity with MATLAB. If you
desire a more detailed description of the biology behind the
simulator, you should look at the description of stages of the ideal observer.
Starting the simulator
To start the simulator, first make sure that the simulator script files are in
your MATLAB search path. Start MATLAB and then type:
where the '>>' is the MATLAB prompt.
Once you start up the simulator, typing "1" for help will start up
Netscape and bring you directly to this page. Next, you should
immediately be prompted to input a series of parameters for the
input mean background (photons/um2/sec) =
This determines the background luminance for the stimuli. Sine wave gratings
are modulated around this mean intensity. This input intensity is later
translated into the mean number of photons absorbed for each cone.
Number of wavelengths to superimpose =
This sets the number of wavelengths to be used in the stimuli. Each
wavelength is assigned an equal fraction of the background intensity value
so that the total mean intensity will be correct. Wavelengths between
380 and 730 nm at 5 nm increments are acceptable. Each wavelength also
has an associated phase shift to allow the counterphase sine wave
gratings (for isoluminant gratings). A phase shift of 0 means that the
dampened sine wave grating is centered over the cone array.
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© 1995 Andrew Hsu
Last updated 10/19/95
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