Change an image color space by matrix multiplication.
outImage = changeColorSpace(inImage,colorMatrix)
The input image is either an RGB image (m x n x 3) or an XW image but with 3 columns.
For backwards compatibility the routine also works on an inImage that is
a single matrix built from R,G,B, images as
inImage = [ R G B];
The output image is returned in the same format as the input.
The calculation converts the data into an Nx3 matrix and right multiplies
the data with a 3 x 3 color matrix. That is, the matrix converts column
vectors in the input image representation into column vectors in the
output representation.
outImage = [ inImage ] * colorMatrix
where inImage is converted to XW format.