First and second codewords are determined, based on first feature vector components of the image elements in an image block, as representations of a first and second component value. Third and fourth codewords are determined, based on second vector components, as representations of a third and fourth component value. First N1 and second N2 resolution numbers are selected based on the relation of a distribution of the first vector components and a distribution of the second vector components. N1 additional component values are generated based on the first and second component values and N2 additional component values are generated based on the third and fourth component values. Component indices indicative of the generated component values are then provided for the different image elements.