A loop filtering method and loop filter for implementing said method

摘要

The image data is first stored in a storage device 200 before being passed in blocks to a gradient operator 212 in order to determine edge pixels. Based on this result the image data block is assigned 214 to either a boundary or global area and edge information is generated for the image data of the specific area 216,218 with the result being passed to an OR-processor 220 to produce a binary edge map. The filter determiner 252 applies a window of 3x3 pixels to the binary edge map and determines whether the part of the map the window is located in is an edge area or a homogenous area. If determined to be a homogenous area the filter determiner outputs the location of the centre of the window to the average filter which reads the required pixels for calculating centre pixel of the window from the image storing unit 200 and filters them with a first set of weights(fig 4B). If however the area is determined to be an edge region then the filter determiner outputs the same information to the weighted filter and if the centre pixel of the window is not an edge pixel it then filters the pixels read from the store 200 using a second set of weights(fig 4C), if the centre pixel should be an edge point then no filtering takes place.