Images are divided into image regions. The image regions are processed in encoding cycles such that during an encoding cycle, entropy encoding is carried out in a plurality of parallel encoding branches. In each encoding branch the symbols of an image region are encoded by entropy encoding, which is based on one or more probability models, which take into account the frequencies of symbols occurring in image regions. The probability models are adapted on the basis of the symbols occurring in the image region. A common set of probability models is updated at predetermined time intervals on the basis of frequencies that are adapted in at least one temporally preceding encoding cycle.