Application of reversible denoising and lifting steps to LDgEb and RCT color space transforms for improved lossless compression

Abstract

The lifting step of a reversible color space transform employed during image compression may increase the total amount of noise that has to be encoded. Previously, to alleviate this problem in the case of a simple color space transform RDgDb, we replaced transform lifting steps with reversible denoising and lifting steps (RDLS), which are lifting steps integrated with denoising filters. In this study, we apply RDLS to more complex color space transforms LDgEb and RCT and evaluate RDLS effects on bitrates of lossless JPEG-LS, JPEG 2000, and JPEG XR coding for a diverse image test-set. We find that RDLS effects differ among transforms, yet are similar for different algorithms; for the employed denoising filter selection method, on average the bitrate improvements of RDLS-modified LDgEb and RCT are not as high as of the simpler transform. The RDLS applicability reaches beyond image data storage; due to its general nature it may be exploited in other lifting-based transforms, e.g., during the image analysis for data mining.