Efficient Mid-band Exchange Coefficient Watermarking System

DCT-based watermarking systems are widely used in protection of multimedia content. The two-dimension DCT and its counterpart Inverse 2-D DCT, are the most complex parts in the DCT-based watermarking systems. One of the DCT-based watermarking systems is the Mid-band Exchange Coefficient watermarking algorithm, which encodes one-bit of the binary watermark image into one 8x8 sub-block of the host image by ensuring that the difference of two mid-band coefficients is positive in case of the encoded value is 1. Otherwise, the two mid-band coefficients are exchanged. Efficient algorithm and structure of the Mid-band Exchange Coefficient watermarking system are proposed which use pruning 2-D DCT to compute the two mid-band coefficients only and don't need to use the 2-D IDCT. The Proposed structure is implemented on Xilinx Virtex 800 FPGA chip. The proposed structure consumes about third of the area, and half of the computing time of the traditional structure.