The main objective in developing a robust image watermarking technique is to obtain the highest possible robustness without losing the transparency. To achieve this objective, this paper presents a new optimal robust image watermarking technique based on singular value decomposition (SVD) using differential evolution algorithm (DE). The singular values (SV) of the host image are modified by multiple scaling factors to embed a watermark image. The modifications are optimised using DE to achieve maximum robustness and transparency Experimental results show that the proposed approach can effectively improve the quality of the watermarked image and the robustness of the embedded watermark against various attacks. (C) 2008 Elsevier B.V. All rights reserved.