A DCT-Based Watermarking Technique for Image Authentication

This paper presents a novel DCT-based watermarking method for image authentication. In this method a watermark in the form of a visually meaningful binary pattern is embedded for the purpose of tamper detection. The method embeds one watermark bit in each DCT block by shifting a randomly selected coefficient to have a mapped value, in a coefficient-binary-mapping function, that is identical to the watermark bit. The method was tested under different attacks and was found to provide good detection performance while maintaining the quality of the watermarked image.