On the Application of Haar Wavelets to Locally Progressive Encoding of Grey-level Images

Abstract. In the paper, a new original procedure for the evaluation of discrete Haar spectra for separate fragments (blocks) of a digital image is proposed. The procedure explores specific properties of Haar wavelets, refers to the assumption that Haar spectrum of the whole image is known, and is much faster than direct evaluation of Haar spectral coefficients for the respective image blocks. It is shown that the developed procedure can be successively applied to implementing of a locally progressive image encoding idea. The essence of the latter – selected blocks of the image under processing are compressed into a bit stream with increasing accuracy. To translate the idea into action, direct employment of hyperbolic image filters is proposed. Preliminary experimental results show that the developed approach leads to reasonable image compression ratios and sufficiently high quality of restored image blocks..