Comparison with blocking effect between four base functions in DCT method and OBDCT method
K. Kobayashi, Hideo Sawami · 2004
When DCT (discrete cosine transform) method as a standard transform coding is used to extend images at higher compression ratio, it is difficult to eliminate degradation of image quality due to blocking effect. We quantify and analyze blocking effect for the DCT and OBDCT(overlapping block DCT) methods corresponding to four bases as degradation of image quality caused by quantization error. We clarify theoretically that the OBDCT method with type-I, III bases show the least blocking effect.It is concluded that the OBDCT method is more effective transform coding than the DCT method with data compression and image extension since it did not occur blocking effect visually from results of subjective comparison and enough image quality is kept.