Improved Watermarking Scheme Using Discrete Cosine Transform and Schur Decomposition
This addresses the need for improved image protection against illegal copying, though it appears to be an incremental improvement in watermarking techniques.
The paper tackles the problem of limited capacity in existing watermarking channels by proposing a new robust method that adds the triangular matrix from Schur decomposition to the DCT transform of the host image, with results showing robustness against various attacks including JPEG compression, noise addition, and cropping.
Watermarking is a technique which consists in introducing a brand, the name or the logo of the author, in an image in order to protect it against illegal copy. The capacity of the existing watermark channel is often limited. We propose in this paper a new robust method which consists in adding the triangular matrix of the mark obtained after the Schur decomposition to the DCT transform of the host image. The unitary matrix acts as secret key for the extraction of the mark. Unlike most watermarking algorithms, the host image and the mark have the same size. The results show that our method is robust against attack techniques as : JPEG compression, colors reducing, adding noise, filtering, cropping, low rotations, and histogram spreading.