Method and apparatus for recording and reproducing electronic watermark information, and recording medium

• US 6,535,614 B1
• Filed: 08/24/1998
• Issued: 03/18/2003
• Est. Priority Date: 09/03/1997
• Status: Expired due to Term

• Current Assignee: Hitachi Consumer Electronics Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshiura, Hiroshi, Takeuchi, Toshifumi, Arai, Takao, Kimura, Hiroyuki
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US09/139,112
• Time in Patent Office: 1,667 Days
• Field of Search: 382/10, 382/232, 382/236, 382/306, 348/473, 375/240.08, 375/150, 380/54, 380/201, 380/204
• US Class Current: 382/100
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 21/23892 involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

At recording of a video signal, with electronic watermark information being embedded therein, on a recording medium, a reference signal which is formed differently from the watermark information is inserted to the video signal. At reproduction of the video signal, the luminance of the watermark information is modified based on the reference signal.

Claims

1. A method of reproducing electronic watermark information comprising the steps of:

detecting a reference signal for detecting electronic watermark information from a recording medium having recorded thereon a video signal, the electronic watermark information being embedded in the video signal by alteration of a luminous value of a luminance signal included in the video signal, and the reference signal being inserted in the video signal at a position different from a position of embedment of the electronic watermark information; and

modifying a luminous value of the electronic watermark information based on the reference signal;

.

wherein the modifying step includes the step of calculating a drop of a gain of the reference signal; and

wherein the detecting step includes the steps of

generating an electronic watermark information position detection signal based on a sync signal, and

generating a reference signal position detection signal based on a sync signal.

2. An apparatus for reproducing electronic watermark information comprising:

an electronic watermark information detecting circuit which detects electronic watermark information from a video signal;

a reference signal detecting circuit which detects a reference signal; and

a modification circuit which modifies an amplitude of the electronic watermark information based on an amplitude of the reference signal;

wherein the modification circuit includes a gain drift calculating circuit which calculates a drop of a gain of the reference signal;

wherein the electronic watermark information detecting circuit includes an electronic watermark position generating circuit which generates an electronic watermark information position detection signal based on a sync signal; and

wherein the reference signal detecting circuit includes a reference signal position generating circuit which generates a reference signal position detection signal based on a sync signal.