colorBlockMatrix

 Create a matrix to render SPD data into RGB

       bMatrix = colorBlockMatrix(wList,extrapVal)

 We render spectral data in the scene and optical image windows as RGB
 images.  The matrix returned by this routine is used to calculate R,G and B 
 values from the SPD.  The entries in each column of this matrix
 defines how to sum across the wavebands.   

 By default, the wavelengths from 400-490 add to the blue channel, from
 500-600 add to the green channel, and 610-700 add to the red channel.
 Infrared wavelengths add a weak gray signal, which is, by default, to
 zero. When we are trying to visualize IR, it is useful to set a value of
 0.1 or 0.2.

 wList: the list of wavelengths in the SPD to be rendered.
 extrapVal: Sets how much the infrared wavelengths contribute

 The bMatrix is interpolated from the default matrix to accomodate
 other wavelength sampling lists.

 Examples:
     wList = [400:5:700]; bMatrix = colorBlockMatrix(wList);
     figure; plot(wList,bMatrix)

    wList = [400:5:900]; 
    bMatrix = colorBlockMatrix(wList,0.1);
    figure; plot(wList,bMatrix)

 Copyright ImagEval Consultants, LLC, 2003.