cmatrix

 result = cmatrix(matrixtype, spacetype)
 
 Returns a 3x3 color matrix used by changeColorSpace.

 matrixtype has the following options:
    'lms2opp' -- cone coordinate to opponent (Poirson & Wandell 1993)
    'opp2lms' -- inverse of the above matrix
    'xyz2opp' -- xyz to opponent (CIE1931 2 degree XYZ)
    'opp2xyz' -- inverse of the above matrix
    'lms2xyz' -- Hunt-Pointer-Estevez transformation from cone
                 to XYZ, normalized for D65 (lms=[100 100 100] for D65).
    'xyz2lms' -- inverse of lms2xyz.
    'xyz2yiq' -- convert from XYZ to YIQ
    'yiq2xyz' -- inverse of the abvoe matrix
    'rgb2yuv' -- convert from RGB to YUV (YCbCr) for JPEG compression
    'yuv2rgb' -- inverse of the above matrix
    'xyz2srgb' -- from XYZ to sRGB values
    'srgb2xyz' -- inverse of the above matrix
             (the above are not dependent on device calibration)

    'rgb2lms' -- monitor rgb to cone coordinate
    'lms2rgb' -- inverse of the above matrix
    'rgb2xyz' -- rgb to xyz 2 degree.
    'xyz2rgb' -- inverse of the above matrix
             (The above transformation matrices are based on the
              calibration of the monitor used in Poirson&Wandell(1993) 
              experiment. If possible, you should provide this 
              matrix based on calibration data of your own device,
              instead of using this one. This is only a default when you
              don't have calibration data available for your device).

 spacetype specifies what type of xyz space (CIE1931 2 degree or 
 CIE1964 10 degree) is required.
    spacetype = 2: cie1931 2 degree XYZ   (default)
    spacetype = 10: cie1964 10 degree XYZ
   
 Xuemei Zhang 3/11/96
 Last modified 1/22/98