Embodiments of the present disclosure relate to the field of picture processing. Especially, the embodiments are directed to improving the deblocking filter of an image coding device. During the deblocking, at most a number MA of sample values of the first coding block adjacent to the block edge are modified and at most a number MB of sample values of the second coding block adjacent to the block edge are modified; or at most a number MA of sample values of the second coding block adjacent to the block edge are modified and at most a number MB of sample values of the first coding block adjacent to the block edge are modified, MA≠MB.