Watermark technique using frequency domain

Watermarking is a commonly used technique to hide information in images to discourage unauthorized copying. One of the important issues of watermarking is the robustness subject to lossy compression of the watermarked image. In this paper, a technique of hiding the watermark in the middle frequency portion of the original image is proposed. The modification of the mid-frequency coefficients corresponds to the quantization table in the JPEG standard. With this technique, the watermark can survive when the watermarked image is compressed using the JPEG compression scheme. Moreover, it is independent in the sense that it does not require the information of the watermark image and the original image in the extracting process.