3. The method claimed in claim 2 wherein the limits of said variation intervals in said two color difference signals are interdependent on variation limits of a third color difference signal for the associated luminance region.
2. The method claimed in claim 1 wherein the number of bits in said second words is constant, and said second words in each table are representative of variation sub-intervals chosen in accordance with a quantification law of the full variation interval of the respective color difference signal for the associated luminance region.