Abstract: The present disclosure relates to encoding and decoding of a picture or a plurality of pictures (e.g. video) using a neural network which is partially trained online. Accordingly, at an encoder one or more layers are selected which are to be trained. Then, the training of the neural network is performed in which parameters of the selected layers are updated. The parameters of the remaining layers are maintained and not updated. The updated parameters are provided within a bitstream. The picture(s) is/are also encoded. The decoder receives an indication of the updated parameters, updates only those parameters indicated, and applies the so obtained neural network.