MATLAB Source Code for DWT-Based Digital Watermarking Implementation

This documentation presents a MATLAB source code implementation of DWT-based digital watermarking. The program provides complete functionality for both watermark embedding and extraction processes utilizing the Discrete Wavelet Transform (DWT) algorithm. Digital watermarking represents a technique for embedding hidden information within digital media, serving purposes such as copyright protection, identity verification, and security enhancement. The DWT method, a fundamental signal processing technique, decomposes signals into different frequency subbands, enabling more effective watermark concealment and improved robustness against various attacks. The implementation employs MATLAB's built-in wavelet toolbox functions including dwt2() for 2D discrete wavelet transformation and idwt2() for inverse transformation. Key algorithmic steps involve: 1) Decomposing the host image into LL, LH, HL, and HH subbands using multi-level DWT, 2) Embedding watermark data in selected coefficient bands through quantization-based modulation, 3) Reconstructing the watermarked image using inverse DWT. The code features modular structure with separate functions for embedding (watermark_embed()) and extraction (watermark_extract()), complemented by comprehensive comments and configuration parameters for wavelet type selection and embedding strength adjustment. This well-documented source code offers clear implementation details and adjustable parameters, making it suitable for educational purposes and practical applications in digital watermarking research. The program demonstrates proper handling of image preprocessing, coefficient modification strategies, and robustness considerations common in DWT-based watermarking systems.