[calFormat,nX,nY] = ImageToCalFormat
Take an nX (col dimension) by nY (row dimension) by k image
and convert it to a format that may be used to Psychtoolbox
Note that the order nX,nY makes sense for thinking about images
in terms of x and y coordinates, but that the order is backwards
from the MATLAB convention of row dim then column dim.
See also CalFormatToImage
8/04/04 dhb Wrote it.
7/16/07 dhb Update help line.
10/2/09 dhb Try again on making help clear.