Codage hybride pour la compression d’images

Abstract

As the use of digital images is up Data compression of digital images acquired is becoming increasingly important to meet storage needs. One of the challenges of compression is to compress the images at high efficiency while maintaining the quality of the reconstructed image. In this research, we present a hybrid algorithm proposed for compression of color images based on two two-dimensional discrete transform, the wavelet transform DWT and the cosine transform DCT, the proposed algorithm starts by using a single step the discrete wavelet transform for decomposing an image into four sub-bands; low frequency and high frequencies, each block of "n × n" of the sub-band low frequency (LF) are transformed two-dimensional DCT using, in following applies to the quantification and arithmetic coding for the compressed image Our compression algorithm proved good compression ratio, and compared as a function of PSNR. Keywords : Image compression, wavelete, compression ratio,PSNR