Deringing and deblocking DCT compression artifacts with efficient shifted transforms

A new method, using weighted combinations of shifted transforms, is developed for deringing and deblocking DCT compressed color images. The method shows substantial deringing improvement over prior methods, maintains comparable deblocking and shows comparable PSNR gains. The method automatically adapts to input image quality, and it may be implemented using low-complexity, swath-based processing. Multiplier-less transforms better suited for parallel hardware implementation are developed. Finally, PSNR comparisons are provided for the different methods. The new method using the DCT transform offers good visual results with PSNR comparable to prior work, and the multiplier-less transforms offer good visual results at a slight loss in PSNR.