JP2017011664A - Noise addition device - Google Patents

Abstract

In a space-saving configuration, it is possible to degrade the image quality of a captured image without affecting the visual perception of a human viewing a voyeur object.
An oscillator 32 has a predetermined frequency that is not perceived by human eyes when an image is viewed, and is perceived by human eyes when a captured image obtained by capturing the image with a camera is viewed. A pulse signal for superimposing the changing noise on the image light is generated. The drive circuit 30 converts the pulse signal so as to generate an overshoot when the electronic shutter 12 is changed from the open state to the closed state, and opens and closes the electronic shutter 32 at a predetermined frequency based on the converted signal. .
[Selection] Figure 9

Description

  The present invention relates to a noise adding device that adds noise to various videos such as a movie screened in a theater or the like and a video projected by a projector.

  A movie is created with a huge investment of money. On the other hand, illegal voyeurism in movie theaters has become a big problem with the spread of miniaturized and highly sensitive video cameras.

  In recent years, there has been a video explaining that voyeurism is a criminal act before the start of screening in a movie theater, but it is not a complete measure. For example, the current situation is that new movies that are considered voyeurized are leaked to the Internet, and pirated versions of various media such as DVD (Digital Versatile Disk) are sold. These illegal activities continue to cause tremendous damage to the film industry.

  Therefore, various techniques are considered as techniques for preventing voyeurism of movies. For example, Patent Document 1 proposes that flickering is generated in a voyeurized image by irradiating light on a screen at a specific frequency using an irradiation unit different from a movie projector. Thereby, the image quality of the voyeur image can be lowered.

JP 2010-278573 A

  However, in the technology described in Patent Document 1, it is necessary to provide an irradiation unit separately from the movie projector, and it is necessary to secure a space for arranging the irradiation unit. There is room for improvement.

  The present invention has been made in consideration of the above facts, and is noise-added with a space-saving configuration that can degrade the image quality of the captured image without affecting the human vision of the image. An object is to provide an apparatus.

  In order to achieve the above object, the noise adding device according to the first aspect of the present invention is not perceived by human eyes when viewing an image, and is not perceived by human eyes when viewing a captured image obtained by capturing the image with a camera. And a signal generator that generates a signal for superimposing noise that changes at a predetermined frequency on the image light, and a signal generated by the signal generator on the optical path of the image light. A drive unit that opens and closes the provided electronic shutter at the predetermined frequency; and a frame-shaped shield provided so as to surround the electronic shutter, wherein the electronic shutter and the shield are configured to transmit the image light. It is arranged to shield everything.

  According to the noise adding device according to the first aspect of the invention, the signal generation unit is not perceived by the human eye when viewing the video, and when the video captured by the camera is viewed by the human, A signal for superimposing the noise perceived by the eye and changing at a predetermined frequency on the image light is generated.

  Then, based on the signal generated by the signal generation unit, the driving unit opens and closes a shutter provided on the optical path of the image light at the predetermined frequency. At this time, a frame-shaped shield provided so as to surround the electronic shutter and the electronic shutter shield all of the image light.

  As described above, the frame-shaped shielding object provided so as to surround the electronic shutter and the electronic shutter shield all of the video light, and the electronic shutter is based on a signal for superimposing noise on the video light. By changing the shutter from the open state to the closed state, even when the electronic shutter is small, it is possible to degrade the image quality of the captured video without affecting the visual perception of the person viewing the video. .

  The drive unit according to the first invention converts the signal generated by the signal generation unit so as to generate an overshoot when the electronic shutter is changed from the open state to the closed state, and converts the signal into the converted signal. Based on this, the electronic shutter can be opened and closed at the predetermined frequency.

  According to a second aspect of the present invention, there is provided a noise adding device that is not perceived by human eyes when viewing an image, and is perceived by human eyes when a captured image obtained by capturing the image with a camera is viewed. A signal generator that generates a signal for superimposing noise that changes at the frequency of the image light on the image light, and a shutter provided on the optical path of the image light based on the signal generated by the signal generator A drive unit that opens and closes at a predetermined frequency, and the drive unit converts the signal generated by the signal generation unit so as to generate an overshoot when the shutter is changed from an open state to a closed state. Then, based on the converted signal, the shutter is opened and closed at the predetermined frequency.

  According to the noise adding device according to the second aspect of the invention, the signal generation unit is not perceived by human eyes when viewing the image, and when the captured image obtained by capturing the image with the camera is viewed, A signal for superimposing the noise perceived by the eye and changing at a predetermined frequency on the image light is generated.

  Then, based on the signal generated by the signal generation unit, the driving unit opens and closes a shutter provided on the optical path of the image light at the predetermined frequency. At this time, the drive unit converts the signal generated by the signal generation unit so as to generate an overshoot when the shutter is changed from the open state to the closed state, and based on the converted signal, The shutter is opened and closed at the predetermined frequency.

  Thus, the signal for superimposing noise on the image light is converted so as to generate an overshoot when the shutter is changed from the open state to the closed state, and the shutter is set to a predetermined frequency based on the converted signal. By opening and closing with, the image quality of the shot video can be deteriorated with a space-saving configuration without affecting the human vision of the video.

  According to a second aspect of the present invention, there is provided a drive unit including a switch that switches on and off according to a signal generated by the signal generation unit, an RC parallel circuit that is a parallel circuit of a resistor and a capacitive load, and a DC power supply in series. The shutter can be opened and closed at the predetermined frequency by using a signal corresponding to a voltage at a connection point between the parallel circuit and the DC power supply as the converted signal.

  The drive unit according to the second invention may further include an input side parallel circuit, which is a parallel circuit of a resistor and a capacitive load, provided between the signal generation unit and the switch. Thereby, it is possible to correct the deterioration of the signal waveform due to the capacitance of the switch.

  The drive unit according to the second invention has one end connected to a first connection point between the switch and the input side parallel circuit, and the other end connected to a second connection point between the switch and the RC parallel circuit. And a diode that prevents a current from flowing from the second connection point to the first connection point. Thereby, it is possible to correct the deterioration of the signal waveform due to the capacitance of the switch.

  A signal generation unit according to a second aspect of the present invention includes a synchronization separation unit that detects information representing a horizontal position or a vertical position on a screen of a video signal representing the video, and the horizontal position or vertical detected by the synchronization separation unit. A signal for superimposing the noise on the image light can be generated using information representing the position. This makes it possible to fix the portion where noise is superimposed in synchronization with the video signal.

  The signal generation unit according to a second aspect of the present invention further includes a synthesis unit, and the synchronization separation unit detects information indicating a horizontal position and information indicating a vertical position of a video signal representing the video and displays the synthesis. The unit may synthesize the information indicating the horizontal position and the information indicating the vertical position detected by the synchronization separation unit to generate a signal for superimposing the noise on the video light. As a result, a portion where noise is superimposed can be reduced, and a decrease in average luminance can be suppressed.

  The predetermined frequency is N, the frequency of noise not perceived by the human eye is Z1, the frequency of noise perceived by the human eye is Z2, the frame frequency of the video is P, and the frame frequency at the time of shooting by the camera is V. In this case, the predetermined frequency N is set to a value satisfying two expressions of Z1 = mP + nN and Z2 = mP + nN + kV (where m, n, and k are positive or negative integers). You can also.

  The above Z1 and Z2 are values excluding from 6 Hz to 14 Hz, and Z2 is a value from 6 Hz to 14 Hz as in the invention according to claim 7 from the viewpoint of human perception ability. Can be applied.

  According to the noise load device of the present invention, the frame-shaped shielding object and the electronic shutter provided so as to surround the electronic shutter shield all of the image light, and the electronic shutter causes the noise to be superimposed on the image light. By changing the shutter from the open state to the closed state based on the signal, even if the electronic shutter is small, the image quality of the captured video is degraded without affecting the human vision Can be made.

  In addition, a signal for superimposing noise on the image light is converted to generate overshoot when the shutter is changed from the open state to the closed state, and the shutter is opened and closed at a predetermined frequency based on the converted signal. By doing so, there is an effect that the image quality of the shot video can be deteriorated without affecting the visual perception of the human watching the video with a space-saving configuration.

It is a perspective view which shows schematic structure of the principal part of the movie voyeurism prevention device concerning a 1st embodiment. It is a disassembled perspective view which shows an example of a structure of the electronic shutter which concerns on 1st Embodiment. It is a figure which shows the brightness | luminance change of an ideal horizontal direction. It is a figure which shows the luminance change of a normal horizontal direction. It is a figure which shows the luminance change of the horizontal direction which generated the overshoot. (A) The figure which shows the drive circuit containing an electronic shutter and a switch, (B) The graph which shows the change of the electric potential of DC power supply. FIG. 8A is a diagram showing a drive circuit in which a capacitive load is inserted, FIG. 7B is a graph showing a change in potential of a DC power supply, and FIG. 7C is a circuit diagram equivalent to the drive circuit in FIG. It is a figure which shows the equivalent circuit of an electronic shutter. It is a circuit diagram which shows an example of a structure of the control apparatus which concerns on 1st Embodiment. (A) A circuit diagram showing a part of the drive circuit, (B) a diagram showing a change in output voltage V2, and (C) a diagram showing a change in input voltage V1. (A) The figure which shows the change of the input voltage V1, (B) The figure which shows the change of the output voltage V2, and (C) The figure which shows the change of the output voltage V2. (A) The figure which shows the change of the electric potential of DC power supply Vc when there is no CR parallel circuit, (B) The figure which shows the change of the electric potential of DC power supply Vc when a CR parallel circuit is inserted. (A) Schematic diagram for explaining a method of superimposing shutter noise on video, and (B) Schematic diagram for explaining a state of a captured video obtained by a voyeur camera shooting a video on which shutter noise is superimposed. It is. (A) The figure which shows an example of the projection image represented with the sine wave, (B) The figure which shows an example of the shutter noise represented with the waveform, (C) The figure which shows an example of the projection image modulated with the shutter noise . (A) The figure which shows an example of the picked-up image obtained by image | photographing a normal image | video with a voyeur camera, (B) The figure which shows an example of the image | photographed image obtained by image | photographing the image | video modulated with the shutter noise with a voyeur camera. It is. It is a figure which shows an example of the picked-up image to which noise was added obtained by image | photographing with a voyeur camera. It is a circuit diagram which shows an example of a structure of the control apparatus which concerns on 2nd Embodiment. It is a figure which shows the change of the pulse signal before and behind CR parallel circuit 234. It is a circuit diagram which shows an example of a structure of the control apparatus which concerns on 3rd Embodiment. (A) The figure which shows the change of the electric current which flows into the collector terminal when not inserting a diode, (B) The figure which shows the change of the electric current which flows through the collector terminal when a diode is inserted, and (C) Ideal to a switch It is a figure which shows an input. It is a figure which shows schematic structure of the movie voyeurism prevention apparatus which concerns on 4th Embodiment. 4A is a diagram showing a change in a horizontal synchronization signal, FIG. 4B is a diagram showing a change in a vertical synchronization signal, and FIG. 3C is a diagram showing a change in a signal obtained by synthesizing the horizontal synchronization signal and the vertical synchronization signal. It is a figure which shows an example of the picked-up image to which noise was added obtained by image | photographing with a voyeur camera. It is a figure which shows an example explaining the principle of 5th Embodiment. It is a figure which shows an example which shifts the position of the shielding shutter when the brightness of a projection image | video is dark. It is a perspective view which shows schematic structure of the principal part of the movie voyeurism prevention apparatus which concerns on 5th Embodiment. It is a figure which shows an example of the shielding shutter which concerns on 5th Embodiment. It is a figure which shows an example of the shielding shutter which concerns on 5th Embodiment. It is a figure which shows an example of the shielding shutter which concerns on 5th Embodiment. It is a figure which shows an example of the shielding shutter which concerns on 5th Embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the case where the noise adding device of the present invention is applied to a movie voyeurism prevention device that prevents voyeurism of a movie projected from a movie projector will be described as an example. Thus, a noise adding device for adding noise may be used.

[First Embodiment]
FIG. 1 is a perspective view showing a schematic configuration of a main part of the movie sneak shot prevention device according to the present embodiment.

  As shown in FIG. 1, the movie voyeurism prevention device 10 according to the present embodiment includes an electronic shutter 12 and a control device 14 that controls driving of the electronic shutter 12. The control device 14 corresponds to a signal generation unit and a drive unit of the present invention.

  As shown in FIG. 1, the electronic shutter 12 according to the present embodiment is provided between the lens unit 16 </ b> A of the movie projector 16 that projects an image on the screen 20 and the screen 20. In the present embodiment, as shown in FIG. 1, the electronic shutter 12 is disposed in contact with the lens unit 16 </ b> A of the movie projector 16. The electronic shutter 12 may be arranged away from the lens unit 16 </ b> A as long as a part of the image, more preferably the entire position is included in the range that passes through the electronic shutter 12.

  A control device 14 is connected to the electronic shutter 12, and the control device 14 controls on / off (blocking / transmitting light) of the electronic shutter 12.

  As the movie projector 16 according to the present embodiment, a general projector is used. For example, a controller 18 is connected to the movie projector 16 and receives a video signal representing an image from the controller 18. Then, the movie projector 16 modulates the light incident from the light source 16C by an optical modulator (for example, a liquid crystal display element or DMD (Digital Mirror Device)) 16B based on the received video signal, and the lens unit 16A. The image light modulated via is projected onto the screen 20.

  FIG. 2 is an exploded perspective view showing an example of the configuration of the electronic shutter 12 according to the present embodiment. In the present embodiment, the electronic shutter 12 using transmissive piezoelectric ceramics (PLZT) 24 will be described as an example, but the electronic shutter 12 is not limited to this. Other electronic shutters such as an electronic shutter using liquid crystal may be applied.

  As shown in FIG. 2, the electronic shutter 12 according to the present embodiment includes a polarizer 22, a PLZT 24, and a screen 20 side (projection) provided on the lens unit 16A side (projection light incident side) of the movie projector 16. The analyzer 26 is provided on the light emission side.

  In the present embodiment, as shown in FIG. 2, the PLZT 24 has a groove shape and an electrode is provided in the groove portion. However, the shape of the PLZT 24 and the electrode is not limited to this. Instead, it is possible to adopt various shapes.

  As an example of PLZT24, for example, Shizuoka University paper (Tomio Hirano, “Study on low temperature formation of CSD PLZT ferroelectric thin film using seed layer”, SURE: Shizuoka University REpository, Shizuoka University, September 22, 2000 , P.1-138, [October 24, 2013 search], Internet <URL: http://ir.lib.shizuoka.ac.jp/handle/10297/3241>) Can be adopted.

  As described in the above paper, when the optical axis is x and the plane orthogonal to the optical axis x is the yz plane, by applying an electric field to the PLZT 24, the light in each of the x, y, and z axis directions of the PLZT 24 The refractive index changes. Here, the polarizer 22 is disposed so that the polarization direction is, for example, 45 degrees with respect to the y-axis direction and the z-axis direction, and the analyzer 26 is configured so that the polarization direction is orthogonal to the polarizer 22. Placed in. With this arrangement, when no electric field is applied to the PLZT 24, the light that has passed through the PLZT 24 crystal has the same phase in the y component and the z component, and the polarization direction is kept in the same direction as at the time of incidence. Light is blocked by the photon 26. On the other hand, when an electric field is applied to PLZT 24, the refractive indices in the y-axis direction and the z-axis direction are different, so that each phase gradually shifts while propagating through the crystal of PLZT 24, and elliptically polarized light that combines two components. The light passes through the analyzer 26.

  In the present embodiment, the electronic shutter 12 configured as described above is disposed in contact with the projection light emission side of the lens unit 16A of the movie projector 16. An electronic shutter at a predetermined frequency that degrades the captured image when it is photographed by a camera such as a video camera (hereinafter sometimes simply referred to as a voyeur camera) without affecting the visual perception of the audience watching in the movie theater. Control device 14 controls to drive 12.

  Here, as the predetermined frequency, a frequency that is not perceived by the human eye when viewing the projected image and perceived by the human eye when viewing the captured image taken by the voyeur camera is selected. To do.

  Specifically, the predetermined frequency is N, the frequency of noise that is not perceived by the human eye is Z1, the frequency of noise that is perceived by the human eye is Z2, the frame frequency of the projected image is P, and the voyeur camera takes a picture. When the frame frequency at the time is V, a value satisfying the following equations (1) and (2) is selected as the predetermined frequency N (where m, n, and k are positive or negative integers). .)

Z1 = mP + nN (1)
Z2 = mP + nN + kV (2)

  The control device 14 controls the on / off drive of the electronic shutter 12 at the predetermined frequency N, and noise generated by the electronic shutter 12 (hereinafter sometimes simply referred to as shutter noise) is projected on the projected image. Superimpose. As a result, it is possible to deteriorate the captured video when the voyeur camera is used without affecting the visual perception of the audience watching at the movie theater.

  Further, in the present embodiment, the electronic shutter 12 can be disposed in contact with the projection light emission side of the lens unit 16A, so that the space saving configuration can be achieved as compared with the case where an irradiation unit or the like for emitting light is separately provided. can do.

  Next, the principle of controlling the on / off driving of the electronic shutter 12 in the present embodiment will be described.

  In the case where noise is simply added by driving the electronic shutter on and off, there is a problem that in the captured image, the darkened portion of the screen is not sufficiently darkened because the brightness is reduced.

  In order to solve the problem that the dark part of the screen including the interference does not become sufficiently dark, it is only necessary to drastically reduce the luminance at the changing portion from the high luminance region to the low luminance region as shown on the right side of FIG. Specifically, if the electronic shutter is rapidly changed from the open state to the closed state, it becomes darker rapidly as shown on the left side of FIG.

  The dark part is not sufficiently darkened simply by driving the electronic shutter on and off. This situation is shown on the left side of FIG. The luminance change at this time is as shown in the right side of FIG. In such a way of decreasing the brightness, it is affected by the gently decreasing portion, and human vision does not feel a large change in luminance. The human visual characteristics used here have the O'Brien effect (references (Suetake, “Development of a color vision barrier-free high-speed color conversion system for digital color images based on the Clay-O'Brien illusion effect”, Journal of the Franklin Institute, June 2012) Month)). When the O'Brien effect is used, as shown on the right side of FIG. 5, even if it is a gentle change, it appears to human vision that the brightness has suddenly decreased. When the right side of FIG. 5 is compared with the right side of FIG. 4, the gently changing portion has a similar waveform. However, the right side of FIG. This is the application of the O'Brien effect, which appears to have a sharp drop in brightness and then becomes darker, making it possible to obtain a sufficient disturbing effect.

  A circuit for generating a waveform that causes overshoot in this way will be described with reference to FIGS. 6 and 7. FIG. When driving an electronic shutter, it is necessary to turn it on / off by passing or stopping current. FIG. 7A illustrates an example in which an electronic shutter is driven using a transistor. An equivalent circuit of the electronic shutter is a parallel circuit of a capacitor and a resistor as shown in FIG. Here, since a method for reducing the capacitive load will be described, it is assumed that the electronic shutter includes only a capacitor for simplification. That is, the resistance value is assumed to be very large and capacitive load. Here, an example of driving with a transistor is shown, but the same applies to an FET (field effect transistor) or a current drive IC. Although a circuit example of grounded emitter is shown here, the same effect can be obtained with a circuit configuration other than grounded emitter. These devices can amplify minute currents and control large currents. The transistor has three electrodes, B (base), E (emitter), and C (collector). When a very small current is passed between BEs, a large current flows between CBs, which is combined with the current that flows between BEs and flows out of E. As a result, a large current flows through C and charges the capacitive load C1. Since it is a capacitor, that is, a capacitive load, charge is not accumulated at a time, and charge accumulation increases with the passage of time as shown in FIG. If the capacity of the capacitive load C1 is small, the potential of the DC power supply Vc changes rapidly. However, if the capacity of the capacitive load C1 is large compared to the current, it takes time to change the potential of the DC power supply Vc. This potential change corresponds to the luminance change on the right side of FIG. That is, a rapid potential change is necessary to rapidly reduce the luminance. FIG. 7A shows this solution. In the figure, the capacitive load C1 is an electronic shutter. The total capacitance seen from the transistor is reduced by inserting the capacitive load C2. An equivalent circuit of FIG. 7A is shown in FIG. C3 is the combined capacity of C1 and C2, and (C1C2) / (C1 + C2) <C1. That is, the combined capacitance seen from the transistor is reduced by inserting C2.

  As described above, as shown in FIG. 9, the control device 14 according to the present embodiment includes the oscillator 32 and the drive circuit 30. As shown in FIG. 9, the drive circuit 30 includes a switch 38, a CR parallel circuit 34 in which a capacitive load C2 and a resistor R2 are connected in parallel, and a series circuit in which a DC power supply Vc is connected in series. A CR parallel circuit in which a capacitive load C1 and a resistor R1 are connected in parallel is referred to as an electronic shutter 12. The principle will be described with reference to FIG. Assume that the CR parallel circuit 34 is inserted and the pulse waveform shown in FIG. By adjusting the capacitive load C2 and the resistor R2, the waveform shown in FIG. 10B (hereinafter referred to as an edge waveform) can be output. This output waveform outputs a thin edge at the rise and fall of the input waveform. This waveform is a waveform that generates the overshoot shown in FIG. 5, and brings about the effect shown in FIG. FIG. 11 shows the relationship between C2 · R2 and the shape of the edge waveform. For the input shown in FIG. 11A, FIGS. 11B and 11C show changes due to time constant τ = C 2 · R 2. Here, the time constant τ is the time that falls from the rise to 37%. As shown in FIGS. 11B and 11C, this can be dealt with by adjusting C 2 · R 2 in accordance with the load characteristics of the electronic shutter 12.

  FIG. 12 shows changes in the potential of the DC power supply Vc, which is an input signal to the electronic shutter 12 when the CR parallel circuit 34 of the present embodiment is not provided and when it is not provided. By inserting the CR parallel circuit 34, an edge is generated in the potential of the DC power supply Vc, and a desired O'Brien effect is obtained.

  As described above, the drive circuit 30 of the control device 14 according to the present embodiment switches the on / off according to the pulse signal generated at the predetermined frequency generated by the oscillator 32 as shown in FIG. 38, a CR parallel circuit 34 of a resistor R2 and a capacitive load C2, and a series circuit in which a DC power source Vc is connected in series, and a signal corresponding to the potential at the connection point between the CR parallel circuit 34 and the DC power source Vc. Is used to open and close the electronic shutter 12 at a predetermined frequency. At this time, the drive circuit 30 converts the pulse signal generated by the oscillator 32 so as to generate an overshoot when the electronic shutter 12 changes from the open state to the closed state, and based on the converted signal, the electronic circuit 12 The shutter 12 is opened and closed at a predetermined frequency. The drive circuit 30 corresponds to a drive unit of the present invention, and the oscillator 32 corresponds to a signal generation unit.

  Next, the operation of the movie sneak shot prevention device 10 according to the present embodiment configured as described above will be described with reference to FIGS. FIG. 13A is a schematic diagram for explaining a method of superimposing shutter noise on an image. FIG. 13B is a schematic diagram for explaining a state of a photographed image obtained by photographing the image on which the shutter noise is superimposed by the voyeur camera. FIG. 14A is a diagram showing an example of a projected image represented by a sine wave. FIG. 14B is a diagram illustrating an example of shutter noise. FIG. 14C is a diagram illustrating an example of a projected image modulated by shutter noise. Further, FIG. 15A is a diagram illustrating an example of a captured image obtained by capturing a normal image with a voyeur camera. FIG. 15B is a diagram illustrating an example of a captured image obtained by capturing an image modulated with shutter noise with a voyeur camera.

  In the movie voyeurism prevention device 10 according to the present embodiment, when the movie projector 16 starts projecting a movie onto the screen 20, the control device 14 controls on / off (light blocking / transmitting) of the electronic shutter 12. To start.

  As a result, an image transmitted through the lens unit 16A is projected onto the screen 20 via the electronic shutter 12. That is, since the image is intermittently projected on the screen 20 in accordance with the on / off of the electronic shutter 12, the image projected on the screen 20 has a projected image and shutter noise as shown in FIG. Is multiplied to obtain a projected image modulated by shutter noise. For example, when a projected image represented by a sine wave as shown in FIG. 14A is multiplied by shutter noise that changes so as to cause overshoot as shown in FIG. 14B, FIG. As shown in (C), a projection image modulated by shutter noise is obtained.

  Further, when the video projected on the screen 20 is shot with the voyeur camera in this way, as shown in FIG. 13B, the projection video modulated with the shutter noise and the normal video are shot with the voyeur camera. A captured image multiplied by the captured image is obtained. For example, as shown in FIG. 15A, when a normal video is captured by a voyeur camera and a projection video modulated by the shutter noise described above is multiplied, FIG. A photographed image as shown is obtained.

  At this time, as described above, the predetermined frequency N is set to a value satisfying the above expressions (1) and (2) without affecting the visual perception of the audience watching in the movie theater. When shooting with a voyeur camera, the shot video can be degraded. Further, the electronic shutter 12 is converted so as to generate an overshoot when the electronic shutter 12 changes from the open state to the closed state, and the electronic shutter 12 is opened and closed at a predetermined frequency based on the converted signal, as shown in FIG. As described above, it is possible to superimpose noise with a sufficiently reduced brightness in a dark portion on a captured image captured by a voyeur camera.

  In the following, the principle that the control device 14 can drive the electronic shutter 12 at the frequency N to degrade the video captured by the voyeur camera without affecting the visual perception of the audience watching in the movie theater. Will be described.

  When multiplication of two types of signals is performed, signals of the sum frequency and the difference frequency always appear. For example, when signals of sin θ and sin φ are multiplied, signals (θ−φ) and (θ + φ) appear as shown in the following equation (3).

  In other words, the Fourier series and Fourier transformation that originated in Fourier, a French mathematician who was active in the 18th and 19th centuries, and subsequent research proved that all signals can be expressed by combining trigonometric functions. Yes.

  An image projected in a movie theater is no exception, and can be expressed by a sine wave (sin) and a cosine wave (cos) having different phases and periods.

  A movie usually has a frame frequency of 24 Hz. However, an image with a frame frequency of 24 Hz is visually recognized as flicker by human eyes. For this reason, by cutting the shutter within one frame (inserting a dark frame), a pseudo 48 Hz is realized to prevent flicker. For this reason, movies have basic frame frequencies of 24 Hz and 48 Hz, and can be expanded in Fourier series by 24 Hz. Here, since 48 Hz is twice the frequency of 24 Hz, when the video signal is expanded in Fourier series at 24 Hz, a signal having a frequency that is an integral multiple of 24 Hz appears. For this reason, 48 Hz appears as a frequency twice that of 24 Hz. Since this principle does not depend on the frame frequency of the movie projector 16, the following description will be generalized and the frame frequency of the movie projector 16 will be described as PHz.

  Further, the above-described predetermined frequency (shutter noise frequency) given when the control device 14 drives the electronic shutter 12 is NHz. In this embodiment, an example in which the predetermined frequency is superimposed by the electronic shutter 12 is shown, but the present invention is not limited to this. For example, there is a method in which noise corresponding to shutter noise is directly superimposed on the backlight of the movie projector 16 or the video signal to be projected by the movie projector 16, and these all theoretically have the same principle.

  In addition, a general video camera or the like used for voyeurism has a frame frequency of 30 Hz or 60 Hz, and VHz is used to generalize this.

  When a noise signal of NHz is superimposed on a video signal having a frame frequency of PHz, as shown by the equation (3), signals of (N−P) Hz and (N + P) Hz appear with PHz and NHz as fundamental frequencies. In human vision, the highest brightness part and the lowest brightness part tend to stand out. Therefore, if attention is paid only to the noticeable part, a signal of NHz is sampled at PHz.

  Therefore, a signal of (m × P + n × N) Hz appears from the sampling theorem. Here, m and n are positive or negative integers, and m, n = ± 1, ± 2, ± 3,. For example, when P = 24 Hz and N = 100 Hz, a signal of 100−24 × 4 = 4 Hz or 24 × 5 when m = −4 and n = 1, or when m = 5 and n = −1. A signal of −100 = 20 Hz appears. In the theater, a human appreciates the image projected from the movie projector 16 with shutter noise superimposed.

  By the way, human vision is very sensitive to low frequency flicker. Here, the low-frequency flicker refers to flicker having a frequency that is visible to humans.

  Here, as an example of the low-frequency flicker that satisfies the expressions (1) and (2), a periodic signal of 6 Hz to 14 Hz can be mentioned. Humans generally tend to recognize flicker of 50 Hz or less, but are particularly sensitive to flicker of 15 Hz or less. For this reason, it is necessary to select the frequency of the shutter noise as the predetermined frequency so that the (m × P + n × N) Hz signal does not become a frequency sensitive to human vision. In the above example, Z1 = 24 × 5-100 = 20 Hz, and the spectator views the video with the shutter noise superimposed, but since the value of Z1 is greater than 15 Hz, flicker is relatively recognized. hard.

  The voyeur camera takes a picture of this state. In this case, the captured image obtained by capturing the image projected on the screen 20 with the voyeur camera is obtained by further superimposing the signal of the frame frequency of the voyeur camera. That is, the frame frequency of the voyeur camera is set to VHz, and k = ± 1, ± 2, ± 3,..., (M × P + n × N + k × V) Hz signal is mixed.

  Here, the value of (m × P + n × N) Hz is a frequency that deviates from the frequency band (for example, 15 Hz or less) at which humans can easily see flicker, and the value of (m × P + n × N + k × V) Hz is human. The value of N is selected so that the frequency is easily visible. That is, by selecting a predetermined frequency satisfying the above expressions (1) and (2) as N, it is possible to create a state in which flicker is not visually recognized in the theater but flicker is visually recognized in a sneak shot. Become.

  For example, if P = 24 Hz, N = 233 Hz, and V = 60 Hz, the image projected on the screen 20 becomes 233-24 × 9 = 17 Hz when m = −9 and n = 1, and the flicker described above. It is difficult to see with human vision because it deviates from a frequency at which it is easily perceived. At N = 55 Hz, when m = −2 and n = 1, 55−24 × 2 = 7 Hz, and a signal having a frequency at which humans can easily recognize flicker is mixed.

  On the other hand, when an image on which the shutter noise is superimposed and projected on the screen 20 from the movie projector 16 is shot with a voyeur camera, the values of (m × P + n × N + k × V) are P = 24 Hz and N = In the case of 233 Hz, V = 60 Hz, m = 5, n = −1, and k = 2, (m × P + n × N + k × V) = 5 × 24-233 + 2 × 60 = 7 Hz. In this state, a signal having a frequency at which humans can easily recognize flicker is mixed, and a flicker can be visually recognized.

  As described above, according to the movie sneak shot prevention device according to the first embodiment, when the pulse signal for superimposing the noise on the image light is changed from the open state to the closed state by the drive circuit. Shooting without affecting the visual perception of humans in a space-saving configuration by opening and closing the shutter at a predetermined frequency based on the converted signal. The image quality of the recorded video can be sufficiently degraded.

  In the present embodiment, the example in which the electronic shutter 12 is disposed in contact with the lens unit 16A of the movie projector 16 has been described. However, the present invention is not limited to this. For example, it may be provided in the movie projector 16 (for example, between the lens unit 16A and the light modulator 16B, or between the light modulator 16B and the light source 16C).

[Second Embodiment]
In the second embodiment, an example in which a CR parallel circuit is inserted between an oscillator and a drive circuit will be described. In addition, about the part which becomes the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 17, in the drive circuit 230 of the control device 214 according to the second embodiment, a CR parallel circuit 234 provided between the oscillator 32 and the base terminal of the switch 38, the switch 38, and the CR A parallel circuit 34 and a DC power supply Vc are included.

  Even if the pulse waveform is input to the base terminal of the switch 38, the input waveform to the electronic shutter 12 collapses due to the capacitance between the base and emitter of the switch 38. Therefore, by inserting a CR parallel circuit 234 between the base terminal of the switch 38 and the oscillator 32, an edge can be generated in the input waveform to the electronic shutter 12, as shown in FIG. It is possible to correct waveform deterioration due to gaps.

  As described above, according to the movie voyeurism prevention apparatus according to the second embodiment, the drive circuit 230 corrects the waveform deterioration caused between the base emitters of the switch 38 with respect to the pulse signal generated by the oscillator 32. When the electronic shutter 12 is converted from the open state to the closed state, the electronic shutter 12 is converted so as to generate an overshoot, and the electronic shutter 12 is opened and closed at a predetermined frequency based on the converted signal. Image quality can be sufficiently degraded.

[Third Embodiment]
In the third embodiment, an example in which a CR parallel circuit is inserted between an oscillator and a drive circuit and a diode is further provided will be described. In addition, about the part which becomes the same structure as 1st Embodiment and 2nd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 19, in the drive circuit 330 of the control device 314 according to the third embodiment, a current is provided between the CR parallel circuit 234 and the base emitter of the switch 38 and from the emitter terminal to the base terminal. Including a diode 336, a switch 38, a CR parallel circuit 34, and a DC power source Vc.

  Although the input waveform to the electronic shutter 12 collapses due to the capacitive load between the base and emitter of the switch 38, the collapse of the input waveform to the electronic shutter 12 can be corrected by inserting a diode 336 as shown in FIG. It is. FIG. 20 shows the principle. Assume that an ideal pulse shown in FIG. 20C is input between the base and emitter of the switch 38. It is desirable that the current flowing through the collector terminal is immediately turned OFF, that is, zero after the pulse becomes zero. However, due to the capacitance between the base and collector of the switch 38, the current flowing through the collector terminal does not turn OFF for a while as in the example without the diode shown in FIG. This is because the capacitive load between the base collectors of the switch 38 is charged. On the other hand, when the diode 336 is inserted, it is possible to reduce the extra charge charged in the capacitive load between the base and collector of the switch 38. As a result, as in the example with the diode shown in FIG. 20B, after the pulse waveform becomes zero, the current flowing through the collector terminal of the switch 38 becomes zero in a short time.

  As described above, according to the movie voyeurism prevention apparatus according to the third embodiment, the diode 336 is inserted between the base collectors of the switch 38 of the drive circuit 330, thereby reducing the capacitive load between the base collectors of the switch 38. After the excessive charge to be charged is reduced and the pulse waveform becomes zero, the current flowing through the collector terminal of the switch 38 becomes zero in a short time. As a result, the image quality of the captured video can be sufficiently degraded.

[Fourth Embodiment]
In the fourth embodiment, an example in which the electronic shutter 12 is driven in synchronization with an image will be described. In addition, about the part which becomes the structure similar to 1st Embodiment-3rd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 21, the same video signal as the video signal output from the controller 18 to the movie projector 16 is input to the control device 414 of the movie voyeurism prevention device 410 according to the fourth embodiment.

  The control device 14 includes a synchronization separation unit 420 that detects horizontal position information and vertical position information on the screen from the input video signal, and a synthesis circuit that combines the horizontal position information and vertical position information detected by the synchronization separation unit 420. 422 and a drive circuit 330 that receives an output signal from the synthesis circuit 422. The drive circuit 330 corresponds to a drive unit of the present invention, and the synchronization separation unit 420 and the synthesis circuit 422 correspond to a signal generation unit.

  The sync separator 420 separates and outputs the horizontal sync signal from the video signal as shown in FIG. 22A, and separates the vertical sync signal from the video signal as shown in FIG. 22B. Output.

  As shown in FIG. 22C, the synthesis circuit 422 outputs a pulse signal obtained by synthesizing the horizontal synchronization signal and the vertical synchronization signal output by the synchronization separation unit 420.

  The drive circuit 330 receives the pulse signal output from the synthesis circuit 422 as an input and drives on / off of the electronic shutter 12.

  In this way, by driving the electronic shutter 12 in synchronization with the video signal of the movie projector 16, as shown in FIG. 23, the noise generation position in the captured image obtained by the voyeur camera is fixed. Only a part of the image can be obtained, and a decrease in average luminance can be suppressed.

  In the fourth embodiment, the case where the pulse signal obtained by synthesizing the horizontal synchronization signal and the vertical synchronization signal output by the synchronization separation unit 420 is described as an example. However, the present invention is not limited to this. Alternatively, the horizontal synchronization signal or the vertical synchronization signal output by the synchronization separation unit 420 may be output as it is as a pulse signal without using a synthesis circuit.

  In the first to third embodiments, the case where the pulse signal output from the oscillator is converted by the drive circuit is described as an example. However, the present invention is not limited to this. A pulse signal for generating an overshoot may be directly generated when the shutter is changed from the open state to the closed state.

[Fifth Embodiment]
The fifth embodiment includes a circular electronic shutter and a frame-shaped shield provided so as to surround the circular electronic shutter on a plane perpendicular to the optical path direction of the image light. A mode in which the shielding shutter is disposed so as to shield all of the image light will be described. In addition, about the part which becomes the same structure as 1st-4th Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  First, the principle of projection of image light on the screen in the fifth embodiment will be described with reference to FIG. In the fifth embodiment, the shielding object is the adapter 502 made of a substance that shields light. However, the adapter 502 is not limited to the adapter 502 as long as it is a substance that shields light.

  Specifically, the light source 16C is incident on the light modulator 16B after being condensed. Here, in FIG. 24, the optical path of the projected image is totally shielded by the shielding shutter 500, and a part of the optical path of the projected image is transmitted through the electronic shutter 12.

  Here, although the light is diffractive, since the optical path of the projected image is completely shielded by the shielding shutter 500, it is possible to reliably add noise to the image projected on the screen 20.

  Note that the larger the area shielded by the adapter of the projected image, the darker the entire image projected on the screen. Therefore, when the brightness of the entire projected image is insufficient, as shown in FIG. Adjustment is possible by moving the position of the shutter 500 away from the light source. Further, the dotted line portion in FIG. 25 represents the position of the shielding shutter 500 before the movement.

  FIG. 26 is a perspective view showing a schematic configuration of a main part of a video sneak shot prevention device according to the fifth embodiment.

  As shown in FIG. 26, the shielding shutter 500 according to the fifth embodiment is provided between the lens unit 16A of the movie projector 16 that projects an image on the screen 20 and the light modulator 16B. In the fifth embodiment, the case where the shielding shutter 500 is disposed inside the movie projector 16 will be described. However, the shielding shutter 500 may be disposed outside the movie projector 16.

  Here, as shown in FIG. 27, the shielding shutter 500 is provided so as to surround the circular electronic shutter 12 and the circular electronic shutter 12 on a plane perpendicular to the optical path direction of the image light. An adapter 502 is included. In the fifth embodiment, it is assumed that the shielding shutter 500 is disposed so as to shield all the optical paths of the video.

  As described above, in the fifth embodiment, the entire optical path of the image is shielded by the shielding shutter 500, and the passage of light or the non-passage of light is controlled by the electronic shutter 12 which is a part of the shielding shutter 500. Thus, even when the size of the electronic shutter is smaller than the entire optical path of the video, it is possible to prevent the voyeurism of the movie.

  In the fifth embodiment, the case where the shielding shutter 500 is shown in FIG. 27 has been described. However, the present invention is not limited to this. For example, the area ratio between the electronic shutter 12 portion and the shield portion may be changed in the shielding shutter 500 as shown in FIGS.

  In the fifth embodiment, an example in which the shielding shutter 500 is disposed between the lens unit 16A of the movie projector 16 and the light modulator 16B as shown in FIG. 26 has been described. However, the present invention is not limited to this. is not. For example, when the entire optical path of the image can be blocked by the blocking shutter 500, the movie projector 16 (for example, an arbitrary location between the lens unit 16A and the light modulator 16B, the light modulator 16B and the light source 16C, You may arrange | position in the arbitrary positions of the arbitrary places between. Further, when the entire optical path of the image can be shielded by the shielding shutter 500, the shielding shutter 500 may be disposed at an arbitrary position between the lens unit 16A of the movie projector 16 and the screen 20.

  In the fifth embodiment, the electronic shutter 12 is opened and closed at a predetermined frequency based on a signal converted to generate an overshoot when the electronic shutter 12 is changed from the open state to the closed state. Although described, the present invention is not limited to this. For example, noise that changes at a predetermined frequency that is not perceived by the human eye when the image is viewed and is perceived by the human eye when the captured image obtained by capturing the image with a camera is viewed as image light The electronic shutter 12 may be opened and closed at a predetermined frequency based on a signal for superimposing on the electronic shutter.

  In addition, although the control of turning on / off the electronic shutter 12 (blocking / transmitting light) in the fifth embodiment has been described in the control device 14 according to the first embodiment, the present invention is not limited thereto. Is not to be done. For example, on / off (light blocking / transmission) control of the electronic shutter 12 may be realized by any of the control device 214, the control device 314, or the control device 414 in the second to fourth embodiments. .

  The shielding shutter according to the fifth embodiment includes a circular electronic shutter and a frame-shaped shielding provided so as to surround the circular electronic shutter on a plane perpendicular to the optical path direction of the image light. Although the case where it consists of a thing was demonstrated, it is not limited to this. For example, a shielding shutter including a circular electronic shutter and a frame-shaped shielding object provided so as to surround the circular electronic shutter may be used.

  In the first to fifth embodiments described above, the case where movie voyeurism is prevented has been described as an example. However, the present invention is applied to an apparatus that prevents voyeurism of images other than movies. May be. Further, the present invention may be applied to an apparatus that adds noise to a video other than the purpose of preventing video voyeurism. For example, the present invention may be applied to an apparatus that adds noise so that only a part of a video is a non-photographable part.

DESCRIPTION OF SYMBOLS 10 Movie voyeurism prevention apparatus 12 Electronic shutter 14 Control apparatus 16 Movie projector 18 Controller 30 Drive circuit 32 Oscillator 34 RC parallel circuit 38 Switch 214 Controller 230 Drive circuit 234 RC parallel circuit 314 Controller 330 Drive circuit 336 Diode 410 Movie voyeurism prevention Device 414 Control device 420 Sync separation unit 422 Combining circuit 500 Shield shutter 502 Adapter

Claims (10)

Noise that changes at a predetermined frequency that is not perceived by the human eye when the image is viewed and is perceived by the human eye when the captured image obtained by capturing the image with the camera is viewed in the image light. A signal generator for generating a signal for superimposition;
A drive unit that opens and closes an electronic shutter provided on the optical path of the image light at the predetermined frequency based on a signal generated by the signal generation unit;
A frame-shaped shield provided to surround the electronic shutter;
Including
A noise adding device in which the electronic shutter and the shielding object are arranged so as to shield all of the image light.   The drive unit converts the signal generated by the signal generation unit so as to generate an overshoot when the electronic shutter is changed from an open state to a closed state, and based on the converted signal, the electronic unit The noise adding apparatus according to claim 1, wherein a shutter is opened and closed at the predetermined frequency. Noise that changes at a predetermined frequency that is not perceived by the human eye when the image is viewed and is perceived by the human eye when the captured image obtained by capturing the image with the camera is viewed in the image light. A signal generator for generating a signal for superimposition;
A drive unit that opens and closes a shutter provided on the optical path of the image light at the predetermined frequency based on the signal generated by the signal generation unit;
Including
The drive unit converts the signal generated by the signal generation unit so as to generate an overshoot when the shutter is changed from an open state to a closed state, and based on the converted signal, the drive unit A noise adding device that opens and closes at the predetermined frequency.   The driving unit includes a series circuit in which a switch that switches on and off according to the signal generated by the signal generation unit, an RC parallel circuit that is a parallel circuit of a resistor and a capacitive load, and a DC power source are connected in series. 4. The noise adding device according to claim 3, wherein the shutter is opened and closed at the predetermined frequency by using a signal corresponding to a voltage at a connection point between the parallel circuit and the DC power supply as the converted signal.   The noise adding device according to claim 4, wherein the driving unit further includes an input side parallel circuit that is provided between the signal generation unit and the switch and is a parallel circuit of a resistor and a capacitive load.   One end of the driving unit is connected to a first connection point between the switch and the input-side parallel circuit, and the other end is connected to a second connection point between the switch and the RC parallel circuit. The noise adding device according to claim 5, further comprising a diode for preventing a current flow from a connection point to the first connection point.   The signal generation unit includes a synchronization separation unit that detects information representing a horizontal position or a vertical position on a screen of a video signal representing the video, and represents information representing a horizontal position or a vertical position detected by the synchronization separation unit. The noise adding device according to claim 3, wherein the noise adding device generates a signal for superimposing the noise on video light. The signal generation unit further includes a synthesis unit,
The synchronization separation unit detects information representing a horizontal position and information representing a vertical position of a video signal representing the video;
The noise adding unit according to claim 7, wherein the combining unit combines the information indicating the horizontal position and the information indicating the vertical position detected by the synchronization separation unit to generate a signal for superimposing the noise on video light. apparatus. The predetermined frequency is N, the frequency of noise not perceived by the human eye is Z1, the frequency of noise perceived by the human eye is Z2, the frame frequency of the video is P, and the frame frequency at the time of shooting by the camera is V. When
The predetermined frequency N is a value that satisfies the following expressions (1) and (2) (where m, n, and k are positive or negative integers): The noise addition apparatus of any one of Claims.
Z1 = mP + nN (1)
Z2 = mP + nN + kV (2)   The noise adding device according to claim 9, wherein Z1 is a value excluding 6 Hz to 14 Hz, and Z2 is a value from 6 Hz to 14 Hz.