Filtering method for reducing blocking effect and ringing noise of image data

摘要

A gradient of image data is calculated for each pixel of the image data (410) and is compared with a global threshold value (T g ) which is determined based on a predetermined quantization step (420). The gradient data of each pixel is compared with a local threshold value (T n ) which is determined for each block having a predetermined size, (430). An OR operation is performed (440) with respect to the global edge map information and the local edge map information to generate binary edge map information (450). A filter window of a predetermined size is applied to determine whether edges are present (460). The pixel values of the corresponding filter window are filtered pixel by pixel by using predetermined first weighted values to generate a new pixel value if it is determined that edges are not present (485). The pixel values of the corresponding filter window are filtered pixel by pixel by using predetermined second weighted values to generate a new pixel value if it is determined that edges are present (480), while the filtering is not performed if the pixel located at the center of the filter window represents an edge (475).