Performance Analysis of Wavelet Based Transforms in JPEG

In this paper, a performance analysis of different transforms DCT, DWT and a combined approach of DCT and DWT is used to compress a digital image. JPEG is the first international digital image compression standard for continuous-tone still images, both grey scale and color. JPEG is a transform coder, which uses DCT as the default transform. It has been proved that we can easily plug in Discrete Wavelet Transform (DWT) to JPEG standard with minimal changes in the basic operations. The experimental results show that DWT based JPEG gives better quality at higher bit-rates than DCT based JPEG. Since the bit-rate is less. DCT-JPEG outperforms DWT JPEG. But the computational complexity of DWT-JPEG is much higher than that of DCT-JPEG. A combination of DCT and DWT transforms can be used to reduce the computational complexity and also to get better quality image than DCT-JPEG at higher bit-rates.