MATLAB Implementation of DCT Transform for Digital Watermarking

This algorithm utilizes Discrete Cosine Transform (DCT) to implement digital watermark embedding and extraction. The method embeds watermark information into original data through DCT transformation, while embedded watermarks can be recovered using inverse DCT transformation. Key implementation steps include: applying DCT to convert image data into frequency domain coefficients, selecting mid-frequency coefficients for watermark embedding to balance robustness and invisibility, and modifying coefficients using quantization-based embedding techniques. Digital watermarking technology plays crucial roles in copyright protection, information authentication, and data integrity verification. MATLAB implementation typically involves using dct2() for forward transformation and idct2() for inverse transformation, with additional functions for coefficient selection and embedding strength control. The algorithm maintains visual quality while ensuring watermark durability against common image processing operations.