1. Field of the Invention
Embodiments of the present invention generally relate to insertion techniques for watermarks. More particularly, the present invention relates to insertion techniques for low frequency watermarks.
2. Description of the Related Art
Watermarking is a technique that can be used to detect the origin of a copy of audio and/or visual media. This technique is especially beneficial in the motion picture industry. Typically, when a motion picture is released, there is a very large market for unauthorized copies of the motion picture. Watermarking facilitates the detection of the origin of any unauthorized copies. Watermarking information is very critical in eliminating, or at least minimizing, piracy of copyrighted audio/visual content.
Given these potential leaks, a content owner needs forensic tools that enable the tracking of unauthorized copies back to the party who licensed the use of the content, and who was responsible for preventing its further distribution. The ability of the content owners to identify the exact distribution point at which material was stolen can be used as a tool to identify the responsible parties and can act as a deterrent to such theft. A watermark uniquely identifying the licensee of that copy of the content can serve this purpose. This tracking watermark will give content owners a powerful forensic tool against piracy, because it allows them to trace pirated copies to the individual customers (e.g., for video download), or to a specific post-production house, or to the time and location (e.g., for digital cinema) at which theft occurred.
Most watermarking methods use high frequency techniques to insert watermarks into audio/visual content. However, there are problems associated with high frequency watermarking techniques. High frequencies should be avoided because the reduced sensitivity of the Human Visual System (HVS) at high frequencies allows these components to be distorted by processing or attacked by adversaries without significant degradation to the fidelity of the content. Thus, watermark data in these components can be damaged. One might conclude that since there is also reduced HVS sensitivity at low frequencies that low frequencies should be avoided for the same reason. However, the high degree of information in the low frequency components makes them difficult to distort without degrading the fidelity of the content. Most optical and computational processes that are applied to moving imagery and result in “matchable” quality tend to reproduce these low frequency/high information components with high fidelity. For example, camcorder piracy, which often degrades middle and high frequencies to the extent that typical spread-spectrum watermarks are significantly damaged, still generally produces a video stream from which a viewer could describe in detail what is happening in each scene.
Therefore, there is a need in the art for a method and apparatus to provide low frequency watermarking of content.
In one embodiment, the present invention generally relates to a method and apparatus for inserting a watermark onto an illuminated image sequence. A light modulator modulates a light source. A controller controls the light modulator such that a low frequency watermark is inserted onto the illuminated image sequence. In one embodiment a serial and/or parallel configuration may be used in order to insert the low frequency watermark onto the illuminated image sequence. In another embodiment a slit modulator may be used to facilitate high speed film printing.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
The present invention discloses insertion techniques for low frequency watermarks. For some watermarking applications, e.g., per-show fingerprinting of film-based cinema presentation, it is desirable to insert the watermark into an analog signal stream. For low frequency watermarks, this analog insertion can be done in an especially cost-effective manner, since its inherent low frequency nature allows the use of relatively low performance light modulating hardware (e.g., a low resolution liquid crystal light valve panel). Insertion techniques may be used for both printing and projecting stages. It is useful to mark at both these stages, since the film copy can be marked at the printing stage, while time of showing and other temporally dynamic information can be marked at projection time.
For low spatiotemporal frequency watermarking purposes, a low spatiotemporal resolution light modulator is placed in series and/or parallel with a film printer or projector. It modulates the light source that would otherwise evenly illuminate each frame of the film, thus causing a subtle low frequency modulation in the printed or projected film content. The light modulator is controlled by a device that has been programmed in a previous profiling stage to determine appropriate modulations, with an optional sync signal from the projector or printer to help maintain temporal registration. For slit-based high speed film printing, a slit modulator may be used.
If both positive and negative excursions of the low frequency watermark are desired, the “resting” transmissivity of the light modulator 110 must be below 100%, with a consequent decrease in total light throughput that can be compensated by the use of a slightly brighter bulb in light source 115. Alternatively, for some watermarks, positive excursions can be excluded.
The serial 100 and parallel 200 embodiments can also be used together, with negative-going marks handled by the serial branch and positive-going marks handled by the parallel branch. This dual approach allows for enabling both signs (positive/negative) of a watermark without any loss in overall contrast.
For slit-based operation, a feedback-based frame index signal received at controller 325 is useful for maintaining registration. For example, a sensor near the slit could keep approximate track of the start and end of each frame going by, thus enabling more accurate modification of transmissivity for the intended watermark.
Serial and/or parallel embodiments may be implemented using straightforward optical assembly techniques. The fact that basic optical assembly techniques may be used allows the ability to retrofit existing projectors and printers, thus implementing the present invention at a potentially lower cost.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims benefit of U.S. provisional patent application Ser. No. 60/474,900, filed May 29, 2003, which is herein incorporated by reference.
Number | Name | Date | Kind |
---|---|---|---|
5134496 | Schwab et al. | Jul 1992 | A |
5319453 | Copriviza et al. | Jun 1994 | A |
5365552 | Astle | Nov 1994 | A |
5396531 | Hartley | Mar 1995 | A |
5404160 | Schober et al. | Apr 1995 | A |
5488570 | Agarwal | Jan 1996 | A |
5502494 | Auld | Mar 1996 | A |
5515296 | Agarwal | May 1996 | A |
5519780 | Woo et al. | May 1996 | A |
5530759 | Braudaway et al. | Jun 1996 | A |
5568570 | Rabbani | Oct 1996 | A |
5636292 | Rhoads | Jun 1997 | A |
5646997 | Barton | Jul 1997 | A |
5659726 | Sandford et al. | Aug 1997 | A |
5661574 | Kawana | Aug 1997 | A |
5664018 | Leighton | Sep 1997 | A |
5686965 | Auld | Nov 1997 | A |
5696848 | Patti et al. | Dec 1997 | A |
5703793 | Wise et al. | Dec 1997 | A |
5778102 | Sandford et al. | Jul 1998 | A |
5809139 | Girod et al. | Sep 1998 | A |
5825892 | Braudaway et al. | Oct 1998 | A |
5841886 | Rhoads | Nov 1998 | A |
5848155 | Cox | Dec 1998 | A |
5850481 | Rhoads | Dec 1998 | A |
5862260 | Rhoads | Jan 1999 | A |
5881176 | Keith et al. | Mar 1999 | A |
5901178 | Lee et al. | May 1999 | A |
5905819 | Daly | May 1999 | A |
5907619 | Davis | May 1999 | A |
5915027 | Cox et al. | Jun 1999 | A |
5930369 | Cox et al. | Jul 1999 | A |
5933798 | Linnartz | Aug 1999 | A |
5959717 | Chaum | Sep 1999 | A |
5991426 | Cox et al. | Nov 1999 | A |
6018374 | Wrobleski | Jan 2000 | A |
6026193 | Rhoads | Feb 2000 | A |
6037984 | Isnardi et al. | Mar 2000 | A |
6044156 | Honsinger et al. | Mar 2000 | A |
6094722 | Astola et al. | Jul 2000 | A |
6101602 | Fridrich | Aug 2000 | A |
6104826 | Nakagawa et al. | Aug 2000 | A |
6130741 | Wen et al. | Oct 2000 | A |
6137904 | Lubin et al. | Oct 2000 | A |
6188728 | Hurst | Feb 2001 | B1 |
6208735 | Cox et al. | Mar 2001 | B1 |
6208745 | Florencio et al. | Mar 2001 | B1 |
6208746 | Musgrave | Mar 2001 | B1 |
6211919 | Zink et al. | Apr 2001 | B1 |
6224874 | Ehret et al. | May 2001 | B1 |
6373960 | Conover et al. | Apr 2002 | B1 |
6381367 | Ryan | Apr 2002 | B1 |
6449379 | Rhoads | Sep 2002 | B1 |
6535617 | Hannigan et al. | Mar 2003 | B1 |
6553127 | Kurowski | Apr 2003 | B1 |
6563936 | Brill et al. | May 2003 | B2 |
6577744 | Braudaway et al. | Jun 2003 | B1 |
6594373 | Gustafson | Jul 2003 | B1 |
6611608 | Wu et al. | Aug 2003 | B1 |
6624874 | Revelli, Jr. et al. | Sep 2003 | B2 |
6636638 | Yamaguchi | Oct 2003 | B1 |
6665418 | Honsinger | Dec 2003 | B1 |
6674873 | Donescu et al. | Jan 2004 | B1 |
6678389 | Sun et al. | Jan 2004 | B1 |
6683966 | Tian et al. | Jan 2004 | B1 |
6687384 | Isnardi | Feb 2004 | B1 |
6718045 | Donescu et al. | Apr 2004 | B2 |
6721437 | Ezaki et al. | Apr 2004 | B1 |
6757407 | Bruckstein et al. | Jun 2004 | B2 |
6760464 | Brunk | Jul 2004 | B2 |
6763121 | Shaked et al. | Jul 2004 | B1 |
6771795 | Isnardi | Aug 2004 | B1 |
6778678 | Podilchuk et al. | Aug 2004 | B1 |
6785401 | Walker et al. | Aug 2004 | B2 |
6792129 | Zeng et al. | Sep 2004 | B1 |
6792130 | Jones et al. | Sep 2004 | B1 |
6885757 | Bloom et al. | Apr 2005 | B2 |
6944313 | Donescu | Sep 2005 | B1 |
7043019 | Tehranchi et al. | May 2006 | B2 |
7058199 | Au et al. | Jun 2006 | B1 |
7113615 | Rhoads et al. | Sep 2006 | B2 |
7218754 | Schumann et al. | May 2007 | B2 |
7295681 | Lubin et al. | Nov 2007 | B2 |
7298865 | Lubin et al. | Nov 2007 | B2 |
20020076083 | Levy | Jun 2002 | A1 |
20020090110 | Braudaway et al. | Jul 2002 | A1 |
20020141584 | Razdan et al. | Oct 2002 | A1 |
20020168069 | Tehranchi et al. | Nov 2002 | A1 |
20020168082 | Razdan | Nov 2002 | A1 |
20020180973 | MacKinnon et al. | Dec 2002 | A1 |
20030021439 | Lubin et al. | Jan 2003 | A1 |
20030033347 | Bolle et al. | Feb 2003 | A1 |
20030063361 | Ohnishi et al. | Apr 2003 | A1 |
20030112974 | Levy | Jun 2003 | A1 |
20030188166 | Pelly et al. | Oct 2003 | A1 |
20040009763 | Stone et al. | Jan 2004 | A1 |
20040013284 | Yu | Jan 2004 | A1 |
20040064702 | Yu et al. | Apr 2004 | A1 |
20040066951 | Pelly et al. | Apr 2004 | A1 |
20040120523 | Haitsma et al. | Jun 2004 | A1 |
20050018875 | Lubin et al. | Jan 2005 | A1 |
20050025336 | Lubin et al. | Feb 2005 | A1 |
20050036174 | Lubin | Feb 2005 | A1 |
20050175216 | Bloom et al. | Aug 2005 | A1 |
20080212824 | Braudaway et al. | Sep 2008 | A1 |
Number | Date | Country |
---|---|---|
2002359845 | Dec 2002 | JP |
Number | Date | Country | |
---|---|---|---|
20040240705 A1 | Dec 2004 | US |
Number | Date | Country | |
---|---|---|---|
60474900 | May 2003 | US |