Implementation of Wavelet Decomposition-Based Image Digital Watermarking Algorithm Using Arnold Transform

This paper presents a MATLAB implementation of a wavelet decomposition-based image digital watermarking algorithm incorporating Arnold transform, with successful debugging and verification. The implementation follows a systematic approach: first, we apply Arnold transform to the original image using iterative pixel scrambling to enhance randomness and complexity through coordinate permutation. Next, we perform wavelet decomposition using functions like wavedec2() to obtain multi-scale image coefficients across different frequency subbands (LL, LH, HL, HH). Subsequently, we embed watermark information into selected wavelet coefficients by adjusting embedding strength parameters and determining optimal coefficient positions through quantitative analysis, achieving controlled trade-offs between invisibility and robustness. The watermark embedding process involves modifying coefficient values using additive or multiplicative rules while maintaining perceptual quality. Finally, we reconstruct the watermarked image through inverse wavelet transform using waverec2() and validate the algorithm's correctness and stability through systematic debugging tests including PSNR calculations and attack simulations. This wavelet-based digital watermarking algorithm provides substantial security and reliability for image copyright protection and tamper prevention, with the Arnold transform adding an additional layer of security through its periodic scrambling characteristics.