New simple and efficient color space transformations for lossless image compression

We present simple color space transformations for lossless image compression and compare them with established transformations including RCT, YCoCg-R and with the optimal KLT for 3 sets of test images and for significantly different compression algorithms: JPEG-LS, JPEG2000 and JPEG XR. One of the transformations, RDgDb, which requires just 2 integer subtractions per image pixel, on average results in the best ratios for JPEG2000 and JPEG XR, while for a specific set or in case of JPEG-LS its compression ratios are either the best or within 0.1 bpp from the best. The overall best ratios were obtained with JPEG-LS and the modular-arithmetic variant of RDgDb (mRDgDb). Another transformation (LDgEb), based on analog transformations in human vision system, is with respect to complexity and average ratios better than RCT and YCoCg-R, although worse than RDgDb; for one of the sets it obtains the best ratios. (c) 2014 Elsevier Inc. All rights reserved.