1. A video compression decoder comprising: an input receiving a compression encoded bitstream representing transformed pixel differences; an inverse quantisation unit providing re-scaled transform coefficients; an inverse block transform conducting an inverse spatial transform on the transform coefficients to provide decoded pixel differences; a predictor arrangement operating on decoded picture values to provide pixel prediction values for summation with said pixel differences, and an adder arrangement for summing said pixel prediction values and a current block of said pixel differences to form a current block of decoded picture values; wherein the predictor arrangement includes: a first predictor operating wholly outside the current block of decoded picture values to provide first pixel prediction values for summation with pixel differences in said current block of pixel differences; and a second predictor operating at least partly inside said current block of decoded picture values to provide second pixel prediction values for summation with pixel differences in said current block of pixel differences; and wherein the pixel prediction values include a combination of the first pixel prediction values and the second pixel prediction values.