FIELD: steganography; digital watermark detection. SUBSTANCE: proposed method and device are designed to detect watermark in stream of watermark-bearing video data wherein watermark is adjusted to unknown scale out of finite number of scales and is shifted through unknown number of pixels. Video data stream is divided into plurality of scaled equal-size watermark blocks for each predetermined number of scales and plurality of scaled watermark blocks are read out in plurality of read blocks. Each of read blocks is accumulated in predetermined number of read-block bins. Then accumulated read blocks are scaled again and integrated into single composite video-signal block. After that predetermined value, such as that of discrete cosine transformation, is estimated in composite video signal block. This estimate provides for information about presence of watermark in video data stream, scale used for watermark-bearing video signal, and about shift of video signal, if any, inside watermark blocks. Fractional remainder operation is used to find number of read-block bins for each scale under discussion and also to determine bin wherein each read block should be accumulated. EFFECT: facilitated detection of digital watermarks introduced in video data streams subjected to unknown scaling and arbitrary shift. 17 cl, 9 dwg
