Block-based watermarking in the DCT domain

JPEG compression is a widely used compression standard for still images. We present a robust digital image watermarking algorithm that is compatible with a baseline JPEG compression standard. The DCT coefficients in an 80 block have a parent-child structure which is similar to that of wavelet transform. We exploit this property to embed a watermark with maximum strength and least perceptibility. The watermark detection is performed without referring to the original image. Simulation results show that the proposed algorithm is robust against various signal processing techniques and JPEG coding.