Two-Level Wavelet Decomposition of Grayscale and Binary Images for Digital Watermarking

This technique involves performing two-level wavelet decomposition on grayscale and binary images of identical dimensions. The core implementation embeds digital watermark information from the decomposed binary image into the detail subbands (horizontal, vertical, and diagonal components) of the grayscale image's wavelet decomposition. Key functions typically include wavelet transform functions (like wavedec2 in MATLAB) for decomposition, coefficient modification algorithms for watermark embedding, and inverse wavelet transforms for image reconstruction. This watermarking approach enhances copyright protection and integrity verification by making the embedded data resistant to common image processing operations while maintaining visual quality. The wavelet-based method provides superior frequency localization compared to traditional DCT-based techniques, allowing more robust watermark placement in high-frequency detail components where human visual perception is less sensitive.