DWT-Based Digital Watermarking Algorithm Implementation

This project presents a MATLAB-implemented digital watermarking algorithm based on Discrete Wavelet Transform (DWT). The algorithm implements complete watermark embedding and extraction processes, along with a series of attack resistance experiments, demonstrating excellent performance. Through this algorithm, digital watermarks can be embedded into images for applications such as copyright protection and authentication. During the embedding phase, the watermark is inserted into the frequency domain of the host image using DWT decomposition, typically implemented through MATLAB's wavelet toolbox functions like wavedec2() for 2D decomposition. This frequency-domain approach ensures both robustness and invisibility of the watermark. The implementation involves selecting appropriate wavelet families (e.g., Haar, Daubechies) and decomposition levels to optimize the trade-off between visibility and robustness. The extraction process utilizes inverse DWT transformation (waverec2() function in MATLAB) to recover the original watermark information from the watermarked image. The algorithm employs correlation-based detection or thresholding techniques to accurately extract the embedded watermark data. To evaluate the algorithm's robustness and performance, we conducted comprehensive attack experiments including geometric attacks (rotation, scaling, cropping) and signal processing attacks (noise addition, compression). The experimental results demonstrate that the algorithm maintains excellent robustness and reliable extraction performance under various attack conditions. The MATLAB implementation includes systematic testing modules that quantify performance metrics such as Peak Signal-to-Noise Ratio (PSNR) and Bit Error Rate (BER) to validate the algorithm's effectiveness.