SUMMARYIn this paper, to automate broadcast monitoring, which is typified by the verification of the transmission of the material ID code of a commercial message (CM) or program, the authors propose a watermarking scheme without reference images, which does not require a reference image when the watermark sequence is extracted. By embedding a watermark sequence formed by using standard normal random numbers after discretizing the embeddingtarget coefficients in the DCT domain, the proposed technique makes a reference image unnecessary when the watermark sequence is extracted. In addition, since the proposed technique enables a watermark image having the desired image quality (PSNR) to be achieved for any image, it has the advantage that the image quality can always be maintained regardless of the image. Therefore, the same procedure can always be used to embed the watermark sequence in a full-motion video image without obtaining parameters for each image and to extract that watermark sequence without using a reference image. The authors used simulations to verify that an image quality of at least 56 dB, which is the HDTV digital VTR guideline, can be maintained even in the watermarked image, that the watermark sequence can be extracted without using a reference image, and that the proposed technique is robust with respect to MPEG.