Patent Application
20100103331
The invention relates to a video recording prevention system. In particular, the invention relates to the combination of frequency and spectral domain solutions for the prevention of illicit video recording.
The advent of highly portable camcorders has enabled moviegoers to wrongfully and surreptitiously capture the video content of movies displayed in theaters. In an effort to combat such activities, some theaters have incorporated systems for preventing the recording of movie content or degrading video captured by camcorders. The approaches have varied, but each has attempted to exploit the differences between the optical technology of camcorders and the human optical system.
To degrade captured video, some theaters have employed the use of ultraviolet or infrared light, both of which are invisible to the human optical system but detectable and recordable by typical camcorders. Because ultraviolet light (UV) or infrared light (IR) can conceivably be detected by those seeking to record movie content and such people could conceivably implement spectral filters on their camcorders, the use of UV and IR is discouraged.
Some theaters have attempted to prevent video recording by the use of frequency modulation which may deliver, for example, a copyright infringement warning detectable and recordable by typical camcorders as part of video degradation. Unfortunately, the frequency modulation method is discouraged because it is dependent on a camcorder's shutter mechanism and introduces a flicker visible to the human optical system which results in an unpleasant viewing experience for the audience.
It is therefore desirable to develop an improved video recording prevention system.
The present invention is directed to an anti-recording apparatus having the combination of a frequency modulation domain component and spectral domain component which are detectable by a recording device.
The frequency domain solution of the invention can also take advantage of aliasing artifacts that a camcorder will experience when operated under certain conditions. With regards to alias artifacts, it is important to understand that the Shannon theorem suggests that the camcorder sampling rate should be at least twice the rate of a film rate to avoid the possibility of an alias effect. As such, a key feature of the invention is to use greater frame rates. Because DLP® (digital light projection) technology can easily provide frame rates of up to 144 Hz in the motion picture images 20, the use of such frame rates can be readily implemented in theatres to increase the likelihood of aliasing in camcorders. Camcorders typically sample at about 60 Hz. In a preferred embodiment, the frame rate is at least 144 Hz, thereby making this frequency solution more effective at causing aliasing for camcorders having higher sample rate capability.
The advantage of the frequency domain is that there is no extra hardware required and this component is highly effective at high shutter speeds, because camcorders will capture warning message frames or copyright infringement message frames. Further, if the shutter speed is slow, (e.g. 1/15 sec or 1/60), the picture quality to the viewer of the camcorder recording will likely be degraded, even if the warning message frames or copyright infringement message frames are not captured by the camcorder. It is important to point out that the human visual system is such that as frame rates go under approximately 50 Hz, individual frames become detectable to humans as jitter.
Shutter speed (speed of an opening or capture time duration) of a camcorder dictates the amount of light that can be admitted to a CCD. High speeds admit or collect less light and low speeds admit or collect more light. Low speeds, however, may cause blurring if fast moving objects are recorded. As such, if an infringer is selecting shutter speeds to avoid blur or avoid warning message frames, the infringer may not have the camcorder optimized for proper image brightness or contrast.
Further, the embodiment in
As a result, a video recorder or camcorder used in this environment described in
Regarding the spectral domain solution, it takes advantage of the high sensitivity in near IR region (up to 1 micron=1000 nm) in silicon cells in camcorders. This IR is invisible to viewers, but capturable by recording equipment. Although the sensitivity in UV is relatively low in comparison with that in IR, silicon cells surprising still capture UV light. Further, it is important to note that the spectral component is effective regardless of shutter speed. Slow shutter speeds of the camcorder will tend to lead to whole pictures being washed out. Camcorders which use high shutter speeds will still tend to perceive the alphanumeric characters appearing as warning messages in the regions 21, 22 when such messages are inscribed on the mirror 17; however, the regions 21, 22 will not be visible to moviegoers.
The implementation of the combination of the frequency and spectral domain solutions turns out to be effective because each solution compensates for the weakness of the other solution. The weakness of the spectral component is that it can be defeated by stacking filters of multiple wavelength domains in front of the camcorder; however, the use of such filters reduces transmission of visible light. With light transmission low, the pirate would have to slow the shutter speed, which in turn degrades picture quality in the form of blurred images. The weakness of the frequency domain component is that it can be defeated with slow shutter speed; however, when the shutter speed is low, the camcorder is more susceptible the UV and IR spectral domain solution.
In sum, the combination of frequency domain and spectrum domain methodologies makes it significantly more difficult for copyright infringers to illicitly record motion pictures in theatres.
The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. For example, although camcorder is repeatedly mentioned, the invention is intended to be applicable to other types of video cameras. Further, other embodiments can include varying the frame rate of the projector at rates not perceptible to the moviegoer during the course of operation, which has the intended result of confusing the infringer by making it such that at optimized conditions in terms of shutter speed or sampling rates for defeating the frequency domain components will change during the course of a movie, which means that the movie frame frame can vary during the course of showing a movie. Further, the intensities of the UV light 16a and IR light 16b can vary collectively, independently, or randomly (i.e. they can increase and decrease together or one can increase while the other decreases or does not vary) to make it more difficult for a pirate find and use correct filters for the different intensity conditions. Another aspect of the invention is that a warning message frame is intended to include some frame having some content that does not necessarily comprise alphanumeric characters but would be objectionable to a viewer if seen by the viewer while viewing actual video frames of a movie.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US07/14951 | 6/27/2007 | WO | 00 | 12/21/2009 |
