Investigating Lossy Image Coding Using the PLHaar Transform
Joshua Senecal, Peter Lindström, Mark A. Duchaineau, Ken Joy · Data Compression Conference · 2005
Summary form only given. We developed the piecewise-linear Haar (PLHaar) transform (Senecal, J.G. et al., Proc. 12th Pacific Conf. on Computer Graphics and Appl., p.371-80, 2004), an integer wavelet-like transform. PLHaar does not have dynamic range expansion, i.e., it is an n-bit to n-bit transform. To our knowledge, PLHaar is the only reversible n-bit to n-bit transform that is suitable for lossy and lossless coding. We are investigating PLHaar's use in lossy image coding. Preliminary results from thresholding transform coefficients show that PLHaar does not produce objectionable artifacts like previous n-bit to n-bit transforms, such as that of Honyang Chao et al. (CFH) (see Advances in Computational Mathematics, Lect. Notes In Pure and App. Math., vol.202, p.13-38, 1999). Also, at lower bitrates PLHaar images have increased contrast. For a given set of CFH and PLHaar coefficients with equal entropy, the PLHaar reconstruction is more appealing, although the PSNR may be lower.