Abstract: The present invention relates to signal coding, and particularly, though not exclusively, to coding of video signals, especially using conditional replenishment coding, where information is transmitted only in respect of elements of a frame of the picture which have changed relative to the previous frame; the transmitted data being used at a receiver to update a stored version of the picture. According to one aspect of the present invention there is provided a method of coding a set of values comprising selecting that one of a plurality of possible sequences of the values which has the highest correlation between successive values in the sequence, and supplying representations of those values to an output; wherein some of the representations are the differences between the relevant value and a prediction based on at least the immediately preceding value in the selected sequence. Although the method is applicable to other forms of signal, it finds particular application in video coding.