Detecting a change between images is performed more effectively when a measure of change is used for the detection that depends on a length of the code blocks to which the images are individually entropy-encoded, and which are allocated to different sections of the respective image, since the length of these code blocks is also available without decoding. This uses the fact that the length or amount of data of a code block directly depends, in large parts, on the entropy and hence on the complexity of the allocated image section, and that changes between images are, with high probability, also reflected in a change of complexity.