A Hybrid JPEG & JPEG 2000 Image Compression Scheme for Gray Images

The main purpose of image compression is to reduce the redundancy and irrelevancy present in the image, so that it can be stored and transferred efficiently. The compressed image is represented by less number of bits compared to original. Hence, the required storage size will be reduced, consequently maximum images can be stored and it can transferred in faster way to save the time, transmission bandwidth. The Joint Photographic Expert Group (JPEG) , based on the Discrete Cosine Transform (DCT). It has been one of the most widely used compression methods. Although hardware implementation for the JPEG using the DCT is simple, the noticeable “blocking artifacts” across the block boundaries cannot be neglected at higher compression ratio. In addition, the quality of the reconstructed images is degraded by the “false contouring” effect for specific images having gradually shaded areas. The Discrete Wavelet Transform (DWT) based coding, on the other hand, has been emerged as another efficient tool for image compression mainly due to its ability to display image at different resolutions and achieve higher compression ratio. In lossless compression scheme, i.e. DWT the reconstructed image is identical to the original image. In Lossy compression scheme, i.e. DCT the reconstructed image contains degradation relative to the original.