Filtering based on activities inside the video blocks and at their boundary

The present invention relates to a filtering method and a filter, which are used in connection with digital video transmission. The filtering is performed at the receiver side, and the method is especially suitable to be used in connection with mobile terminals and other terminals operating at relatively low transmission line rates. The invention relates to a filtering method used for a video signal at the receiver. It is mostly suited for video compression algorithms utilizing DCT-based video compression technology. In the invention the boundaries () between adjacent video blocks (Band B) are filtered based on the amount of activity inside the adjacent video blocks and the activity at the boundary between the adjacent video blocks. If the filtering according to the invention is performed, it is focused to a certain number of bits () close to the boundary (). The filtering is done by adjusting the numerical values of each video pixel close to the boundary towards a reference line, which is defined as a linear equation leading from the numerical value of a first reference pixel () to the numerical value of a second reference pixel (). The reference pixels () are selected from the adjacent video blocks to present the smooth movement over the boundary between the adjacent video blocks (Band B).