5. The method claimed in claim 1 wherein prior to encoding, two analog color difference signals are corrected into two corrected color difference signals having peak-to-peak amplitudes equal to said peak-to-peak amplitude of an analog luminance signal, and said analog luminance signal and said corrected luminance signals are converted into said digital luminance signal and said two digital color difference signals in accordance with a same sampling quantification scale.
1. A method for encoding a digital luminance signal and two digital color difference signals having high bit-rates and composed of first words representing color picture elements into an encoded digital luminance signal and two encoded digital color difference signals having low bit-rates and composed of second words, wherein a predetermined peak-to-peak luminance amplitude is split into luminance regions that are each associated with two tables of second words of said two encoded signals respectively representative of predetermined variation sub-intervals in the two color differences for luminances lying within one of said luminance regions, and wherein said first words of said two color difference signals representing a picture element are encoded into two second words that are selected from the two respective tables associated with the luminance region including the luminance of said picture element and that are representative of two sub-intervals in the luminance region respectively including the two color differences of said picture element.