MATLAB-Based Image Watermarking: Inserting and Extracting Watermarks Between Images

MATLAB programming enables the insertion of one image as a watermark into another image, along with the capability to extract the watermark later. This process leverages MATLAB's comprehensive image processing toolbox. The implementation typically involves several key steps: First, use MATLAB's imread() function to load both images - the host image (original image) and the watermark image. The watermark image often requires resizing using imresize() to match appropriate dimensions before insertion. For watermark insertion, common techniques include alpha blending or discrete wavelet transform (DWT) methods. Alpha blending can be implemented using weighted addition of pixel values, while DWT-based approaches provide better robustness by embedding watermarks in frequency domains. The processed image can be saved using imwrite() function. Watermark extraction involves reverse engineering the insertion algorithm. For alpha blending, subtraction operations can recover the watermark, while DWT methods require inverse transformation. MATLAB's image processing functions like imsubtract() and wavelet reconstruction functions facilitate this extraction process. By developing appropriate MATLAB scripts, this watermarking process can be automated, making it efficient for digital rights management applications. The code typically utilizes matrix operations for pixel-level manipulations, ensuring precise control over watermark transparency and positioning parameters.