What is Pure Payload

DCT and wavelet based techniques have been widely used in image processing, for example, the applications involving JPEG, MPEG and JPEG2000. To combine the advantages of DCT and wavelet, we introduce in this chapter a novel multilevel DCT decomposition method by exploiting the modified inverse Hilbert curve. The experimental results showed that the proposed multilevel decomposition can extract characteristic DCT coefficients and assign the coefficients to new neighborhoods with distinct frequency properties. We discuss a powerful reversible data hiding algorithm in JPEG images based on this new multilevel DCT. This lossless data hiding algorithm features a key-dependent (multilevel structure) coefficient-extension technique and an embedding location selector, and it can achieve high quality reconstructed images with disparate content types.