In one embodiment, the method includes obtaining a pixel value difference between two successive pixels. The two successive pixels are on a block boundary. The method further includes calculating the filtering coefficient based on the pixel value difference, and obtaining four successive filtered pixel values based on the filtering coefficient. The four successive pixels include the two successive pixels used in the obtaining a pixel value difference, and two of the four successive pixels are included in a first block and two of the four successive pixels are included in a second block.