Reproducing sepia tone images. The image is scanned using conventional
RGB light and added infrared wavelengths. Using L*a*b* color coordinate system,
"L"-channel values are determined by the infrared channel only, and "a" and "b"
channels are filled with respective benchmark values that represents the yellow-brown
sepia background tone of the original. This new L*a*b* data is converted to appropriate
output device color space.