Abstract
An improved steganographic method is proposed in this paper. Two distinct methods are combined to achieve possibly high data hiding capability with high visual quality. The proposed method shifts the last n nonzero AC coefficients from S JPEG block, and changes the magnitude values of the first n nonzero AC coefficients from T JPEG blocks. S and T blocks are determined by the number of nonzero JPEG coefficients in the block. Zero run-length modification method improves the robustness against statistical attack based on magnitude histogram. Magnitude modification method improves the visual quality. This combination complements each other.