The L*a*b* space is perceptually uniform, i.e., the
Euclidean distance between two different colors corresponds
approximately to the color difference perceived by
the human eye (Hunt, 1991). In order to carry out a
detailed characterization of the image of a food item and
thus more precisely evaluated its quality, it is necessary
to know the color value of each pixel of its surface. However,
at present available commercial colorimeters measure
L*a*b* only over a very few square centimeters, and thus
their measurements are not very representative in heterogeneous
materials such as most food items