Source Code for DCT-Based Watermarking Implementation in Grayscale Images

This MATLAB source code implements a Discrete Cosine Transform (DCT)-based watermarking technique for grayscale images. The algorithm operates in the frequency domain by embedding a sequence of pseudo-random real numbers into selected DCT coefficients. The implementation includes key functions for coefficient selection, perceptual masking based on Human Visual System (HVS) characteristics to ensure watermark invisibility, and blind extraction procedures. The watermark embedding process utilizes HVS masking properties to maintain visual quality while embedding robust identification data. A significant advancement of this technique is its blind recovery capability - the embedded watermark sequence can be extracted without reference to the original uncorrupted image. This represents a major improvement over conventional methods that require comparison between watermarked and original images. Digital watermarking has been established as a viable solution for copyright protection and multimedia authentication in network environments. The technology enables identification of document authors, owners, distributors, and authorized consumers through embedded digital signatures. The code implementation includes modules for DCT transformation, coefficient quantization, pseudo-random sequence generation, and correlation-based detection algorithms for reliable watermark extraction.