Abstract:
A projection system has a projector having a frame rate exceeding human flicker sensitivity. The projector having warning message frames in between actual video frames. The warning frames are not detectable to humans. A light source which emits infrared light and ultraviolet light at wavelengths and intensities detectable by movie cameras (e.g., camcorders) and undetectable to humans.

Description:
FIELD OF THE INVENTION 
       [0001]    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. 
       BACKGROUND OF THE INVENTION 
       [0002]    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. 
         [0003]    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. 
         [0004]    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&#39;s shutter mechanism and introduces a flicker visible to the human optical system which results in an unpleasant viewing experience for the audience. 
         [0005]    It is therefore desirable to develop an improved video recording prevention system. 
       SUMMARY OF THE INVENTION 
       [0006]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic illustration of a theatre. 
           [0008]      FIG. 2  is a side view of the implementation of the spectral domain component according to the invention. 
           [0009]      FIG. 3  is top view of the implementation of the frequency modulation domain component and spectral domain component according to the invention. 
           [0010]      FIG. 4  is front view of the implementation of the frequency modulation domain component and spectral domain component according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]      FIG. 1  shows the layout of a theatre or cinema  10 , which can employ anti-piracy utilities such as frequency domain solutions which will now be described. As shown in  FIG. 1 , the theatre  10  employing the invention comprises of a projection room  12 , viewer seats  13  in steps, and a projector  14  which projects motion picture images  20  on a screen  11 . From here, the use of software manipulation in the projector  14  enables the use of the frequency domain solution. The frequency domain solution of the invention utilizes the different inherent sensitivities between the human visual system and a camcorder which are, respectively an integration system and a sampling sampling. In light of these differences, warning message frames or copyright infringement message frames can be included in between the movie frames or actual video frames on the screen such that the moviegoer will not perceive these messages. On the other hand, these messages will be captured by the movie camera or camcorder, as long as the shutter speed is set at a sufficiently fast speed. However, as the infringer slows the shutter speed to avoid warning message frames, the camcorder&#39;s propensity to record blurred moving images increases. 
         [0012]    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. 
         [0013]    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. 
         [0014]    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. 
         [0015]      FIG. 2  shows a side view of a theatre or cinema  10 , which can employ frequency domain solutions in combination with the spectral domain solution, which will now be described. As shown in  FIG. 2 , the theatre  10  comprises a projection room  12 , viewer seats  13  in steps, projector  14 , and screen  11 . The spectrum domain solution requires hardware components. A first component is at least one UV source, which can be UV lasers, and/or at least one IR source, which can be IR lasers. The source or sources which make up the IR source  15   b  and/or UV source  15   a  is shown in  FIG. 3 .  FIG. 2  shows the sources as reference numeral  15 .  FIG. 2  shows just a single component for the light source to illustrate an embodiment where there is one device that produces both IR and UV light or other embodiments where the source or sources can be positioned at different locations in the theatre  10  which includes locations along the top of the front of the theatre  10 . The invention further includes an electronically controlled rotating mirror (or polygon mirror or functional equivalent)  17  attached to the ceiling of the theatre  10  which is used to collectively project the IR and/or UV light  16  toward the screen  11 . The UV and/or IR light  16  incident on the screen then propagates into the theatre for potential illicit video recorders to capture. In a preferred embodiment, alphanumeric characters can be inscribed in the mirror which can contain a warning message that is detectable by camcorders, but not visible to the moviegoers. In such an embodiment, the entire screen  11  can be irradiated with IR or UV light and the alphanumeric characters can form a pattern of absence or lack of the IR or UV light. 
         [0016]      FIG. 3  shows a top view of the combination of the methodologies in a presently preferred embodiment. The frequency modulation domain component is captured in the motion picture images  20  being projected onto screen  11 . The spectral domain component according to the invention utilizes the rotating mirror  17  in concert with a distinct UV source  15   a  and a distinct IR source  15   b  positioned at opposite sides of the front wall of the theatre  10 . The UV light  16   a  and IR light  16   b  are shown propagating from opposite sides of the front wall. The rotating mirror reflects the UV light  16   a  and IR light  16   b  toward the screen  11 . Regions  21  and  22  contain images associated with the UV light  16   a  and IR light  16   b,  respectively, which can degrade and deter video recording. 
         [0017]      FIG. 4  shows the front view of the screen in  FIG. 3  according to another. The UV light  16   a  and IR light  16   b  are projected on the entire screen  11 . The collection of alphanumerical characters shown in the region  21  are portions of the screen  11  not irradiated with UV light  16   a . The collection of alphanumerical characters shown in the region  22  are portions of the screen  11  not irradiated with IR light  16   b.  In such an embodiment the regions  21 ,  22  scan back-and-forth in opposite directions to one another. These regions  21 ,  22  contain warning or copyright messages or other objectionable material that will be invisible to the moviegoer, but perceptible to the camcorder. An alternative embodiment includes only a portion of the screen receiving the UV light  16   a  and IR light  16   b    
         [0018]    Further, the embodiment in  FIG. 4  includes the frequency domain solution wherein some frames of the motion picture images  20  contain frames with a warning message or copyright infringement message  20   a,  which will be imperceptible to the moviegoer, but perceptible to a camcorder, provided that a sufficiently fast shutter speed is used. As long as such frequency domain solution is based on software, the warning message could be manipulated to any shape. 
         [0019]    As a result, a video recorder or camcorder used in this environment described in  FIG. 4  would be subjected to (1) warning message frames (such as the infringement message  20   a  in  FIG. 4 ) which is in between the movie frames or actual video frames and (2) the consistent background of IR and UV light that has message regions  21 ,  22  scanning across the screen. 
         [0020]    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. 
         [0021]    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. 
         [0022]    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. 
         [0023]    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  16   a  and IR light  16   b  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.