Abstract
This study presents an optimization-based image watermarking scheme by using Lagrange Principle. Unlike traditional way of single-coefficient quantization, this study uses multi-coefficients quantization to embed the watermarks. To modify the low-frequency coefficients of discrete wavelet transform (DWT), the Lagrange Principle is applied to derive an optimization-based formula. Experimental results show that the proposed method has good image quality under high embedding capacity and robust to JPEG compression.