Uncompressed multimedia such as data, image, audio and video requires transmission bandwidth and storage capacity. Due to demand for data storage capacity and data transmission bandwidth, Image compression is used which provides data security, reduces the storage requirements, provides rich quality signals for visual data representation and reduces the image fidelity. The focus of this study is the Discrete Cosine Transform (DCT) and Inverse Discrete Cosine Transform (IDCT) based on the sub-band decomposition for image compression. The simulated results are shown that sub-band decomposition based DCT provides good compression rate and better peak signal to noise ratio than conventional DCT.