Wavelet-Based Digital Image Watermarking with MATLAB Implementation

In this documentation, I present a MATLAB implementation for wavelet-based digital image watermarking. This code employs discrete wavelet transform (DWT) to achieve adaptive encoding within the DC components of images. The wavelet transform serves as a mathematical framework that decomposes signals or images into sub-signals or sub-images across different frequency bands. The implementation specifically modifies the approximation coefficients (low-frequency components) through adaptive quantization techniques, allowing seamless embedding of digital watermarks for copyright protection and authentication purposes.

The core algorithm performs multi-level DWT decomposition using wavelet families like Haar or Daubechies, then applies threshold-based modulation to the LL subband coefficients. Key MATLAB functions include wavedec2 for 2D wavelet decomposition, waverec2 for reconstruction, and custom quantization functions for adaptive embedding strength control based on local image characteristics. This implementation demonstrates robustness against common image processing operations while maintaining perceptual transparency. The provided code serves as an educational tool for understanding fundamental principles and practical methodologies in digital watermarking systems.