An efficient sign prediction method for DCT coefficients and its application to reversible data embedding in scrambled JPEG image

In this paper, an efficient DCT sign prediction method is proposed. Unlike the conventional methods that depend on information from both spatial and frequency domains, the proposed method operates solely in the frequency domain by exploiting the pixel value patterns represented by the corresponding DCT basis vectors. In particular, each block is classified into five categories, namely, complex-pattern, complex-nonpattern, simple-smooth, simple-pattern and simple-texture, and each is treated differently using the proposed predictor. The proposed sign prediction method is then applied to realize reversible data embedding using sign information in a scrambled JPEG compressed image. This work is the first of its kind in using sign information for data embedding purposes. Basic performance of the proposed sign prediction and the proposed reversible data embedding method in scrambled JPEG image are verified using standard test images.