SECURING MEDICAL IMAGES WITH ENCRYPTION-BASED WATERMARKING TECHNIQUES

Abstract

This paper presents an encryption-based image-watermarking algorithm for wavelet-based medical images using customized quantization of wavelet coefficients and a chaotic Singular Value Decomposition (SVD) cipher. To strengthen resilience and provide an additional security layer, an SVD-CHAOS embedding and extraction process scrambles the watermark logo during preprocessing. An r-level discrete wavelet transform is applied to the host image during embedding, while adaptive low-bit quantization selects high-frequency coefficients to carry the scrambled watermark. The method is designed to withstand common attacks and recover the hidden watermark without significant degradation of diagnostic image quality. Performance is evaluated using peak signal-to-noise ratio (PSNR), normalized correlation (NC), mean squared error (MSE), and structural similarity (SSIM), and the reported results are compared with related techniques.