MATLAB Implementation of Digital Watermarking Algorithm Using DCT Transformation

This MATLAB implementation provides a functional digital watermarking algorithm that has been thoroughly tested and debugged. The implementation leverages DCT (Discrete Cosine Transform) to improve algorithm stability and effectiveness by embedding watermark information in frequency domain coefficients. Digital watermarking serves as a crucial technology for digital content security, enabling copyright protection and anti-counterfeiting identification through the embedding of invisible markers within digital media. The code implementation includes key components such as: - DCT coefficient calculation using MATLAB's dct2 function - Watermark embedding logic that modifies mid-frequency DCT coefficients - Inverse DCT transformation for watermark extraction - Robustness testing against common image processing operations The algorithm operates by first dividing the host image into blocks, applying DCT to each block, then selectively modifying specific frequency components to embed the watermark data. This frequency-domain approach provides inherent resistance to common image manipulations while maintaining visual quality. The implementation includes both embedding and extraction functions, with error-checking mechanisms to ensure reliable operation across various image formats.