A Deblocking Method using Wavelet Transform for

Abstract — JPEG and MPEG International Standards have been used as formats for compressing and storing still images and moving pictures, respectively. In these standards, DCT (Discrete Cosine Transform) has been being used for compression of data because of compression perfomance. However, there is a problem with blocky noise appearing in reconstructed images when a higher compression rate is set. This is because there are no correlations between DCT blocks as a result of quantizing DCT coefficients, and as the horizontal and vertical dimensions of reconstructed images are scaled up, blocky noise becomes correspondingly more apparent. There have been a lot of studies on reducing blocky noise. One of the most well-known methods is a deblocking edge filter (DEF), which is defined by the international standard of H.263. However, this method increases the computational cost and does not decrease blocky noise at low bit rates. In this study, we propose a new decoding method of reducing blocky noise using inverse wavelet transform for moving pictures. In the proposed method, MPEG-II images, which are low resolution and include blocky noise, are transformed to wavelet transform coefficients. A masking process using these coefficients is also done. As a result of applying the proposed method to a decoder, blocky noise is decreased and the resulting image is clear. I