CRT-based self-recovery watermarking technique for multimedia applications

We propose a Chinese remainder theorem (CRT)-based computationally efficient self-recovery watermarking technique for multimedia applications. Taking few examples of digital images we have shown that the proposed technique can recover the tampered region in the watermarked image quite effectively. Using an optimal quantizing technique we generate a 21-bit watermark from the DCT coefficients of an 8×8 block. This watermark is embedded in a randomly selected block using CRT. Due to modular operations of CRT the watermark embedding and extraction phases are computationally efficient. Experimenting with different size and location of tampering, we have shown effectiveness of our proposed technique. We have also shown the results of a tampered cheque for bank application.