An improved block based EZW technique for low dynamic range image compression

Abstract

This papers deals with improved image compression technique for images having low dynamic range. It is a well known fact that the dynamic range of the images having low intensity variations is less. So by considering this fundamental characteristic into account we can go for image compression at higher ratio with small modifications to the existing algorithms. To achieve the higher compression ratio, block-wise Embedded Zero Wavelet (EZW) is applied on the images by forcing all the blocks in the image to take the same number of dominant and sub-ordinate passes. The number of passes applied on each block of the image will be equal to the lowest number of passes taken by one of the blocks in image. This downside the number of passes applied on the image which reduces the number of bits used for encoding the image which successively increase the compression ratio. The proposed algorithm is analyzed with respect to the normal block-wise EZW by mathematical parameters and visual quality. The mathematical parameters chosen for comparison are Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity (SSIM) index.