GB2417848A

GB2417848A - A method and apparatus for impairing the formation of digital images

Info

Publication number: GB2417848A
Application number: GB0422771A
Authority: GB
Inventors: Ron Vigna
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-09-07
Filing date: 2004-10-13
Publication date: 2006-03-08
Also published as: GB0419756D0; GB0422771D0

Abstract

A method and apparatus for impairing the use of an image capture device 3 to obtain a digital image of an object, preferably a cinema projection screen 2, comprises providing infrared light 5 so that it forms part of the digital image obtained by the device 3, preferably producing a pattern, including identification information within the image. Preferably the infrared light 5 is projected in wavelength ranges of 750nm to 1100nm, 750nm to 850nm, 750nm to 800nm, 780nm to 800nm, 800nm to 850nm or at a wavelength of 1064nm, by at least one laser 1. IR light 5 may reach the image capture device 3 via: reflection from the object; transmission through the object or perforations in it, or; directly from an infrared source. Visible light 7 may be projected onto the object, preferably sharing a common path towards the object with the infrared light 5, the infrared light preferably reflected along the path via an infrared mirror 12, which may be located within visible light source housing.

Description

24 1 7848

METHOD AND APPARATUS FOR IMPAIRING THE FORMATION OF DIGITAL

IMAGES

The present invention relates to a method and apparatus for impairing the use of image capture devices for obtaining a digital image of an object. Particularly, but not exclusively, the invention relates to a method and apparatus for impairing the use of digital image recording equipment for recording a projected image from a cinema screen.

There are many situations in which it is desirable for people to prevent or deter others performing still photography or recording moving images of certain objects. With the prevalence of cheap digital cameras and mobile telephones equipped with digital cameras, such measures are becoming increasingly important, because more and more people carry suitable such devices on their person.

For example, an art gallery may wish to prevent or at least deter its visitors from taking digital images of its paintings. Whilst it is possible to put up signs instructing visitors not to take photographs, these could be ignored by visitors. Instructing security guards to intervene if they spot someone taking a picture could help, but such a system would be costly and difficult to operate in a large gallery containing hundreds of paintings.

There are examples of fields in which unauthorized digital imagery is taken extremely seriously. For example, piracy of film and video material is an increasing problem in the motion picture industry. The Motion Picture Association (MPA) estimates that the annual loss in potential revenues to the US motion picture industry from video and disc piracy is more than $3.5 billion (1.9 billion). A significant problem in the motion picture industry is the pirating of first release films. Newly released films find their way onto the Internet within hours of their first screening. As typical consumer Internet speeds become faster and faster, online film piracy is set to increase.

A common method of producing an unauthorised copy of a film is by recording it from a cinema screen using a digital recording device such as a handheld camcorder.

Although such video copies are usually of an inferior quality to that of the original, pirated copies of movies of this type are increasingly made and sold.

This sort of film piracy has become such a serious problem that some film studios have offered to reward cinema staff who catch cinema goers recording films, and have even started lobbying in the USA to make it a crime to record a film in a cinema. Some distributors of blockbuster films are so fearful that illegal copies will be made by cinema goers that they supply cinemas with specialised equipment in order to help catch people recording their films. For example, it has been known for some distributors to issue night vision goggles to cinema ushers at film premieres to help them catch people filming the movie from their seats.

Metal detectors are also used in some cinemas in order to detect video equipment on cinema goers. However, as semiconductor-based optical detectors become both smaller and integrated with other devices, it is becoming increasingly impractical to remove all recording equipment from cinema goers. For example, as mobile telephone camera technology becomes more and more sophisticated, it is anticipated that it will soon become possible to record a good quality sequence of images using a small, camera- equipped mobile telephone. It will be appreciated that confiscating mobile telephones is not likely to be feasible for cinema staff, as such a move is unlikely to be tolerated by their customers.

There are various known security measures for the prevention of film piracy, such as the provision of watermarks and special codes on film reels so that one can trace where copies originated from. In addition, various methods and systems have been developed for inhibiting off-screen copying of f lms or image sequences US 2004/0033051 describes a method and system for producing and displaying visual presentations which inhibit off-screen duplication by recording images at variable frame rates. The variation of frame rates forms a rate sequence that is recorded simultaneously when the images are recorded. This sequence is then read by the display device so that the images are displayed at the frame rates at which they are recorded. Any unauthorised attempt to record the image sequence off the screen without the rate sequence will only record images displayed at unsynchronized rates.

WO 00/74366 describes a method to prevent video camcorder piracy of motion picture images by varying the frame rate of the displayed motion picture images in a random fashion, thus preventing the camcorder from synchronizing its internal frame with that of the displayed motion picture image.

Such systems suffer from the disadvantage that they can only be used with digital and video projectors. The frame rate of conventional 35 mm movie projectors cannot easily be adjusted and varied to form different rate sequences.

An object of the present invention is to provide a method and apparatus for impairing the use of an image capture device arranged to obtain a digital image of an object.

Another object of the invention is to provide a method for impairing unauthorized off- screen copying of video and film material in cinema theatres which obviates or ameliorates the above described problems associated with conventional methods.

According to a first aspect of the invention there is provided a method for impairing the use of an image capture device arranged to obtain a digital image of an object, the method comprising providing infrared light in such a manner that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object.

This method makes it impossible to use an image capture device to capture a digital image of an object without also capturing infrared light which reduces the quality of the digital image.

Preferred features of this aspect of the invention are set out in Claims 2 to 19.

According to a second aspect of the invention there is provided an apparatus for impairing the use of an image capture device arranged to obtain a digital image of an object, comprising an infrared light source arranged to provide infrared light in such a manner that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object.

This arrangement makes it impossible to use an image capture device to capture a digital image of an object without also capturing infrared light which reduces the quality of the digital image.

Preferred features ofthis aspect ofthe invention are set out in Claims 21 to 38.

Preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure I is a schematic diagram of apparatus for impairing the use of a silicon based optical detector according to a first embodiment of the invention; Figure 2 is a schematic diagram of apparatus for impairing the use of a silicon based optical detector according to a second embodiment of the invention; Figure 3 is a schematic diagram of apparatus for impairing the use of a silicon based optical detector according to a third embodiment of the invention; Figure 4a is a front view of an infrared transmitter box for use in a fourth embodiment of the invention; Figure 4b is a side view of infrared transmitter box shown in Figure 4a; Figure Sa is a side view of the arrangement of an infrared source for use in a fifth embodiment of the invention; Figure Sb is a rear view of the arrangement of an infrared source shown in Figure 5b; Figure 6 is schematic view of the pattern of scan lines of infrared light projected onto a cinema screen used in the embodiment shown in Figure 2; and Figure 7 is schematic view of another pattern of scan lines of infrared light projected onto a cinema screen suitable for use in embodiments of the invention.

Figure 1 shows an infrared source 100 comprising an infrared laser, an object 200 and a recording device 300. The recording device 300 includes a silicon based optical detector 400.

In the arrangement shown in Figure l, the recording device 300 is arranged such that the silicon based optical detector 400 receives visible light from the object 200. It will be understood that under conventional circumstances, this visible light could be used by the recording device 300 to obtain a digital image ofthe object 200. In this embodiment, the silicon based optical detector 400 is a CCD, and the recording device 300 is a conventional digital camera.

The infrared source 100 in this embodiment is arranged so that infrared light 500 of wavelength 800 rim is projected in a path to the object 200 and is reflected from the object 200 towards the CCD 400. The infrared source 100 is therefore arranged to provide the CCD 400 with infrared light of wavelength 800 rim by reflection from the object 200.

Studies have shown that silicon based optical detectors such as CCD receivers in commercially available recording devices such as digital cameras are sensitive not only to visible light in the range of 400 rim to 750 nm, as one might expect, but also to non- visible wavelengths of infrared light in the range from 750 rim to 1200 nm. As a consequence, conventional recording devices will form a digital image on this basis of both received visible light and received invisible infrared light. In such circumstances, the infrared light has the effect of appearing as grey light in the resultant digital image.

It is therefore the case that the CCD 400 shown in Figure 1 not only detects the visible light from the object 200, but also detects the infrared light from the infrared source 100 reflected from the object 200. In Figure 1, the infrared source is arranged to provide a spot of infrared light on the object 200. The infrared reflection from this spot appears as a grey spot on the digital image obtained by the recording device 300. This grey spot therefore obscures the portion of the digital image that would have been formed from the visible light originating from the area of the infrared spot had it not been present. If the intensity of the reflected infrared light from the spot is sufficient, then the grey spot will completely mask the area of the object covered by the spot in the digital image.

Thus, the received infrared light from the infrared source has the effect of reducing the quality of the digital image of the object 200 obtained by the recording device 300.

Consequently, the product of the recording exercise is useless. Not only does this protect the original source image, by rendering the recorded version unsuitable for viewing, but it deters the operator of the recording device 300 from attempting to make copies in the future. Such methods are especially useful in environments such as art galleries in which it may not be feasible to prevent visitors from taking digital images, and in which impairing the use of recording equipment may act as a strong deterrent.

For example, in a practical implementation of this embodiment of the invention, the spot of infrared light on the object could be placed over an important part of the object, for example over the face of a portrait in an art gallery.

In alternative embodiments the infrared source can be arranged to move the infrared light from the infrared laser in such a way that the spot of infrared light moves over an area of the object 200. In this a way a larger portion of the digital image recorded by the recording device will be obscured.

In further embodiments, an optical device can be arranged between the infrared laser and the object such that the beam of infrared light from the infrared source is spread.

With this arrangement the area of the infrared spot on the object will be increased, resulting in the obscuration of a larger portion of the digital image recorded by the recording device.

Whilst the infrared source 100 in Figure 1 is arranged to provide infrared light with a wavelength of 800 nm, other embodiments can use any infrared wavelength that silicon based optical detectors are sensitive to, i.e. wavelengths in the range from 750 nm to 1200 nm.

Furthermore, studies have also shown that conventional semiconductor based optical detectors are generally most sensitive to infrared light in the near infrared part of the spectrum in the range from 750 nm to 850 nm. Therefore, in some embodiments it is advantageous to use wavelengths in the range from 750nm to 850 nm, in order to maximise the deterioration of the digital image formed by the recording device 300 for a given power of the infrared source 100.

It has been found that the shorter the wavelength of the infrared light emitted by the source 100, the less power is required by the source to cause the same level of deterioration to the digital image formed by the recording device 300. However, the closer the infrared light wavelength is to the range of visible wavelengths, the more visible the infrared light becomes to the human eye. It has been found that the range of infrared light wavelengths from 800 nm to 850 rim provides a good balance of causing a large amount of deterioration to a digital image for a given infrared source power, whilst remaining invisible to the human eye Although the upper boundary of the visible spectrum is usually taken to be 750 nm, it is known that some people can see light up to wavelengths of 780 nm. A range of infrared light of wavelengths greater than 780 rim could be used to ensure that the light from the infrared source could not be seen by any viewers.

In other embodiments, infrared light with a wavelength of from 750 rim to 800 nm can be used. Using wavelengths in this range has the advantage that an optical filter could not be used to block the infrared light without also blocking out at least a portion of the visible light from the object 200. This is because infrared filters are broadband and remove a large range of wavelengths. Therefore, it would be impossible for the owner of the recording device 300 to circumvent the method of impairing digital image capture by fitting a suitable filter to remove the infrared light without affecting the quality of the image. This is because in order to remove infrared light with a wavelength of from 750 rim to 800 nm, the filter would also remove a portion of the visible light of wavelength smaller that 750 nm.

A range of 780 rim to 800 nm can be used to provide infrared light that is very close to the visible range, but that would not be seen by any viewers. This range would also have the advantage that it would be impossible to filter out without affecting the visible spectrum.

In other embodiments still, the infrared source 100 can be arranged to transmit infrared light at a wavelength of 1064 nm. Although, at this wavelength more power would be required in order to substantially degrade the recorded image, the design of the system would become more economical since less expensive mass produced lasers transmit infrared light at this wavelength.

In this embodiment, the infrared source 100 is a laser, but it can be an infrared lamp, a combination of infrared lamps and lasers or any other type of infrared source that can be configured to provide infrared light of a suitable wavelength.

In alternative embodiments, an infrared source can be arranged to provide a blanket of infrared light over the object. This can be achieved, for example, by arranging an infrared tube above the object.

In other embodiments still, infrared lamps may be arranged around the object to illuminate the object with infrared light.

As discussed, the recording device 300 in Figure 1 is a conventional digital camera.

However, the recording device can be any device capable of recording a still digital image, such as a mobile telephone equipped with a camera. Furthermore, the recording device 300 need not be restricted to capturing still digital images, but could be a device capable of obtaining moving images, such as a digital camcorder. In addition, the recording device 300 could be capable of obtaining both still and moving digital images.

Although Figure 1 shows an arrangement in which the infrared light is provided to the recording device by reflection from the object, it should be understood that the method of the present invention has broader applications than this.

For example, the recording device 300 can be provided with infrared light from the infrared source 100 that has been transmitted through the object 200. To achieve this, the infrared source lOO can be placed on the other side of the object 200 from the recording device 300, with the infrared light directed towards the recording device.

Such methods are suitable for objects that are not reflective to infrared light but are instead transparent to infrared light.

In addition, the infrared light source 100 can be arranged to illuminate the semiconductor based optical detector 400 of the recording device 300 directly, without infrared light being transmitted by or reflected from the object 200.

Embodiments of the invention such as those described in relation to Figure 1 have many practical applications, and are suited to any application in which it is desired to impair the use of semiconductor based optical detectors for obtaining digital images of an object.

A second embodiment of the invention will be described with reference to Figure 2.

Figure 2 shows a laser projector 15 comprising a laser 1, a cinema screen 2, an infrared reflector 12, a cinema projector 20, and a digital video recorder 3.

The cinema projector 20 comprises a xenon lamp 8, arranged to provide a visible light source, a housing 9 for the xenon lamp 8, a film reel 10 and a lens 11. The xenon lamp 8, the film reel 10 and the lens 11 of the cinema projector 20 operate in a conventional manner to project a visible image from the film reel 10 on to the cinema screen 2.

The digital video recorder 3 comprises a semiconductor based optical detector in the form of a CCD 4 and is capable or recording moving digital images in the conventional manner. It will be appreciated from the foregoing description that the CCD 4 of digital video recorder 3 is also sensitive to infrared light.

In this embodiment, the laser projector 15 is arranged to project infrared light 5 with a wavelength of 820 nm. The laser I is operated in a power range of 3 W and complies with Maximum Permissible Exposure (MPE) regulations and British Standard BSEN 60825. Alternatively, the laser may be operated at any power setting from 1 W to 10 W. As the area of the screen increases the power of the laser can be increased.

The infrared light 5 is provided from the laser 1 to the infrared reflector 12. The reflector 12 is gold-coated glass and reflects infrared but allows visible light to pass through. In other embodiments, the infrared reflector 12 could be made from any optical broadband material that has one of its faces coated with 750nm to 1100nm reflectance coating. Alternatively, a more selective reflectance coating that is specifically matched to the wavelength or wavelength range of the infrared source could be used.

The visible light 7 from the xenon lamp 8 passes through the film reel 10 and into the lens 11 before passing through the infrared reflector 12 and towards the screen 2.

Therefore, the screen 2 will be illuminated with visible light from the projector 20 and infrared light from the laser 1.

The infrared light from the laser 1 is arranged to fall onto a spot on the screen and be reflected towards the audience (who would typically be seated between the projector 20 and the screen 2). On this basis, the reflected infrared light from the spot on the screen wild have the effect of impairing the quality of the moving digital images captured by the digital video recorder 3. Therefore, the apparatus of Figure 2 will undermine the effects of anyone attempting to record the movie projected onto the screen, as the quality of any digital recording will be marred by a grey area corresponding to reflected infrared light from the spot on the screen 2.

In this embodiment, the angle at which the reflector 12 is positioned with respect to the beam of infrared light 5 from the laser is adjustable so that the infrared light can be deflected through a range of angles.

It will be understood that, in the arrangement of Figure 2, the path of visible light 7 from the cinema projector 20 to the screen defines an imaginary cone. In this embodiment, the laser I and the reflector 12 are arranged to project infrared light to the screen 2 within the boundaries of this imaginary cone thus defining the common path for the visible and infrared light. The use of a common path for the infrared light and the visible light is advantageous because the infrared light from the laser 1 that has been reflected by the infrared mirror 12 cannot be blocked on its path to the screen without also blocking a portion of the visible light from the cinema projector 20. Thus, the method of this embodiment cannot be overcome by someone placing a suitable infrared absorbent material between the infrared mirror 12 and the screen 2, without also blocking a portion of the light from the projector 20.

In order to enhance the effect of the invention and produce the greatest deterioration in the quality of the image that can be recorded by the digital video recorder 3, the embodiment of Figure 2 is configured to vary the position on the screen that receives the infrared light from the laser 1. In this regard, the laser 1 is moved in such a way that infrared light is projected onto the screen in the form of a plurality of scan lines.

Figure 6 is a front view of the screen 2 showing the pattern of scan lines projected onto the screen used in the embodiment shown in Figure 2. It can be seen that, beam deflecting mirrors of the laser projector 15 are adjusted so that the infrared light initially falls as a spot position at the top left corner of the screen 2. Adjustments of the beam deflecting mirrors of the laser projector 15 deflect the infrared light from the laser I causing the position of the spot to move horizontally from the top left corner of the screen 2 to the top right corner of the screen. At the top right corner of the screen, the spot is caused to move vertically downward for a short distance before moving horizontally to the left side of the screen. At the leftmost margin the screen, the spot again moves vertically downwards for a short distance and then moves back horizontally to the right side of the screen again. This pattern is continued until the bottom left corner is reached. This produces a plurality of scan lines, and in this embodiment, 250 scan lines are used. In other embodiments, different numbers of scan lines could be used, but 200 to 300 scan lines have been found to be particularly

suitable.

As a result of the scan lines, the digital video recorder 3 does not record a single grey spot on the screen corresponding to the infrared light, but a series of horizontal grey lines. These grey lines would appear over the recording of the movie on the cinema screen by the digital video recorder 3, which would significantly mar the quality of the digital recording.

Figure 7 is a front view of the screen 2 showing an alternative pattern of scan lines projected onto the screen which is suitable for use with embodiments of the invention.

In this arrangement, beam deflecting mirrors of the laser projector 15 are adjusted so that the infrared light initially falls as a spot position at the top left corner of the screen 2. Adjustments of the beam deflecting mirrors of the laser projector 15 then cause the position of the spot to move horizontally from the top left corner of the screen 2 to the top right corner of the screen. At the top right corner of the screen, the spot is caused to move diagonally downward and to the right. At the leftmost margin of the screen, the spot again moves horizontally to the left until the rightmost margin of the screen is reached, at which point the spot moves diagonally downward and to the right again.

This pattern is continued until the bottom left corner is reached. This produces a plurality of scan lines, and in this embodiment, 250 scan lines are used. In other embodiments, different numbers of scan lines could be used, but 200 to 300 scan lines have been found to be particularly suitable.

In other embodiments, the laser projector IS is operated to project a message or identification code on the screen 2. This makes it possible to trace any digital recordings made, as the message or identification code would appear in grey in any recording made by the digital video recorder By use of a suitable code, a pirated film can be traced to a particular cinema or even a particular screening.

A message or identification can be combined with the scan lines of the above described embodiments or any other infrared pattern or image deemed appropriate.

In further embodiments, an optical device may be arranged between the infrared laser 1 and the screen 2 such that the beam of infrared light from the infrared laser is spread over a larger portion of the screen.

In the embodiments described above, the laser projector 15 is generally arranged to project infrared light to the screen continuously whenever the cinema projector is illuminating the screen. However, in alternative embodiments, the laser 1 can be turned off, either periodically or at random intervals. Pulsing the laser on and off has the advantage that it prolongs the life of the laser. A further advantage of pulsing the laser on and off is that this results in the digital image obtained by the digital video recorder 3 comprising a series of flashing grey spots or scan lines, thus making it unpleasant to view. For example, the laser 1 could pulsed on and off at a frequency of 2 Hz so that its effect is clearly noticeable on the recording. Since the pulsing infrared light is invisible to viewer watching the film in the cinema they will not be adversely affected by this.

Although in the above described embodiments only one laser is used, a number of lasers may be used to project infrared light on the screen. The advantage of using a number of lasers is that a larger portion of the screen could be covered in infrared light simultaneously, thus having a more pronounced negative effect on any digital recordings. One or more of the lasers could be replaced by an infrared lamp, a combination of infrared lamps and lasers or any other suitable infrared source.

In the embodiment of Figure 2, the infrared source is arranged to project infrared light onto the infrared reflector 12. However, it will be appreciated that the infrared source could be arranged to project infrared light directly onto the cinema screen without the use of the infrared reflector 12. In other embodiments, the infrared source can be arranged to project infrared light through the screen in a transmission mode, as will be discussed in more detail below. In other embodiments still, the infrared source can be arranged to project infrared light directly to the expected position of the recording device 3. For example, the area in which the audience sits could be flooded with infrared light coming from the direction that they would face, which could be achieved by banks of infrared lamps around the cinema screen 2.

In the embodiment of Figure 2, the xenon lamp 8 is operated at a power of 3000W. In other embodiments, the xenon lamp can be operated at a power setting from 1000 W to 7000W.

In an alternative embodiment of the invention shown in Figure 3, the infrared reflector 12 is arranged inside the housing 9. The reflected infrared light 5 is thereby projected along a common path with the visible light 7 before passing through the lens 11. Such a configuration is advantageous because the infrared light passes through the film 10 thereby allowing the intensity of the infrared light transmitted to the screen 2to automatically adjust to the colours of visible light transmitted. This is because less infrared light will pass through areas of dark colour on the film than will pass through areas of light colour on the film.

A fourth embodiment of the present invention in shown in figures 4a to 4b. In this embodiment, an infrared source comprising an infrared transmitter box 110 is arranged to provide infrared light 5 through a cinema screen 2. Although not shown in Figure 4a and 4b a conventional cinema projector illuminates the screen 2 with visible light in the conventional manner.

Figure 4a is a front view of the infrared transmitter box 110. The transmitter box 110 is provided with a number of infrared transmitting diodes 101 arranged on a printed circuit board 111. The infrared diodes 101 are controlled by a computer processor so that they display a flashing message, which in this embodiment is the name of the cinema and the time and date.

Figure 4b is a side view of the infrared transmitter box 1 10 showing it positioned behind the cinema screen 2. In this embodiment the cinema screen 2 comprises perforations.

The infrared diodes 101 are positioned to correspond with the perforations in the cinema screen 2. The infrared light from the infrared diodes 101 thereby passes through the cinema screen 2 towards the audience and will be picked up by any digital image recording equipment pointed towards the screen 2. Such digital image recording equipment will therefore record the flashing message provided by the transmitter box l l O as grey light overlaid over the visible image on the cinema screen 2, thus impairing the quality of the digital image and enabling the unauthorized recording to be traced.

In other embodiments, the infrared diodes 101 can be controlled by a computer processor to display any suitable flashing pattern. Alternatively, the infrared diodes may not flash and remain on, either displaying a message or pattern.

Although in this embodiment infrared transmitting diodes are used, other infrared sources such as infrared light bulbs or lasers may be used to project infrared light through the screen.

A fifth embodiment of the present invention is shown in 5a to 5b. In this embodiment, an infrared source comprising two infrared transmitter boxes and three infrared flood light sources 102 is arranged to provide infrared light 5 through a cinema screen 2.

Although not shown in Figure 5a and 5b a conventional cinema projector illuminates the screen 2 with visible light in a conventional manner.

Figure 5a is a side view of the arrangement of the infrared source in this embodiment and Figure Sb provides a rear view.

The three infrared flood light sources 102 are placed equidistant in a horizontal row between the two transmitter boxes 110, which are arranged vertically above each other.

The advantage of this configuration is that infrared light from the infrared source will cover a large portion of the screen more efficiently than with only infrared diodes.

Although Figures 5a and Sb show one arrangement of the infrared flood light sources and the transmitter boxes, many arrangements can be envisaged.

In other embodiments, an infrared source can be arranged to provide a blanket of infrared light over the screen. This can be achieved by arranging an infrared tube above the screen.

In other embodiments still, infrared lamps may be arranged around the screen to illuminate the screen with infrared light.

It will be appreciated that the features of the above embodiments of the invention can be combined to form further embodiments. For example, the laser source 1 configured as shown in Figure 2 could be combined with the infrared transmitter box 110 shown in Figure 4a and 4b. In such a configuration, the recording device 300 is provided with infrared light by both reflection from the cinema screen 2 and infrared light through the perforations in the screen. Alternatively, the above described embodiments could be combined with one or more infrared sources arranged to project infrared light directly at the recording device 300.

It is also possible to use mixture types of infrared source (e.g. a mixture of laser and filament types).

It will be appreciated that the above mentioned embodiments of the invention cannot physically prevent someone from using a digital video recorder in an attempt to record the image on the screen, but instead embodiments of the invention provide apparatus that deteriorates the quality of the image to an extent that people will be strongly deterred from using digital video recorders in this way.

Throughout this specification, the term "image capture device" has been used. This term is to be interpreted broadly to cover any type of digital image capturing apparatus whether it is to be used for recording still or moving images or merely relaying still and/or moving images for simultaneous or near simultaneous viewing. It is not intended to cover devices which are purely for the purpose of image capture, but it is intended also to cover devices which have image capture as one of their functions (e.g. mobile telephone with built in digital cameras).

Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims.

Claims

CLAIMS: 1. A method for impairing the use of an image capture device

arranged to obtain a digital image of an object, the method comprising providing infrared light in such a manner that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object.
2. A method according to Claim 1, wherein the method comprises using infrared light in a wavelength range of from 750 rim to 1100 nm.
3. A method according to Claim 2, wherein the method comprises using infrared light in a wavelength range of from 750 nm to 850 nm.
4. A method according to Claim 3, wherein the method comprises using infrared light in a wavelength range of from 750 rim to 800 nm.
5. A method according to Claim 4, wherein the method comprises using infrared light in a wavelength range of from 780 nm to 800 nm.
6. A method according to Claim 3, wherein the method comprises using infrared light in a wavelength range of from 800 nm to 850 nm.
7. A method according to Claim 2, wherein the method comprises using infrared light with a wavelength of 1064 nm.
8. A method according to any one of the preceding claims, further comprising using at least one laser to project the infrared light.
9. A method according to any one of the preceding claims, wherein the method comprises illuminating the object with infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object by reflection from the object.
10. A method according to Claim 9, comprising using a visible light source to illuminate the object by projecting visible light onto the object.
11. A method according to Claim 10, wherein the visible light used to illuminate the object and the infrared light are projected via a common path to the object.
12. A method according to Claim 11, further comprising: using an infrared mirror arranged to reflect infrared light but not visible light; projecting the visible light used to illuminate the object through the infrared mirror and along the common path to the object; projecting the infrared light onto the infrared mirror; and reflecting the infrared light from the infrared mirror along the common path to the object.
13. A method according to Claim 11 or 12, wherein the common path defines an imaginary cone from the visible light source to the object.
14. A method according to any one of the preceding claims, wherein the method comprises illuminating the object with infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object by transmission through the object.
15. A method according to any one of the preceding claims, wherein the method comprises illuminating the object with infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object through perforations in the object.
16. A method according to any one of the preceding claims, wherein the method comprises providing the infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object directly from an infrared source.
17. A method according to any one of the preceding claims, comprising providing the infrared light in such a way so as to produce a pattern on the digital image of the object obtained by the image capture device when capturing an image.
18. A method according to Claim 17, wherein the pattern comprises recognisable identification information.
19. A method according to any preceding claim, wherein the object is a cinema projection screen.
20. Apparatus for impairing the use of an image capture device arranged to obtain a digital image of an object, comprising an infrared light source arranged to provide infrared light in such a manner that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object.
21. Apparatus according to Claim 20, wherein the infrared light source is arranged to provide infrared light in a wavelength range of from 750 rim to 1100 nm.
22. Apparatus according to Claim 21, wherein the infrared light source is arranged to provide infrared light in a wavelength range of from 700 rim to 850 nm.
23. Apparatus according to Claim 22, wherein the infrared light source is arranged to provide infrared light in a wavelength range of from 750 rim to 800 nm.
24. Apparatus according to Claim 22, wherein the infrared light source is arranged to provide infrared light in a wavelength range of from 800 rim to 850 nm.
25. Apparatus according to Claim 21, wherein the infrared light source is arranged to provide infrared light with a wavelength of 1064 nm.
26. Apparatus according to any one of claims 20 to 25, wherein the infrared light source comprises at least one laser.
27. Apparatus according to any one of claims 20 to 26, wherein the infrared light source is arranged to project infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object by reflection from the object.
28. Apparatus according to Claim 27, comprising visible light source arranged to illuminate the object by projecting visible light onto the object.
29. Apparatus according to Claim 28, wherein the apparatus is arranged to illuminate the object with the visible light the infrared light via a common path to the object.
30. Apparatus according to Claim 29, further comprising an infrared mirror arranged to reflect infrared light but not visible light, wherein: the visible light source is arranged to illuminate the object through the infrared mirror and along the common path to the object, the infrared light source is arranged to provide infrared light onto the infrared mirror; and the infrared light mirror is arranged to reflect the infrared light from the infrared source along the common path to the object.
31. Apparatus according to Claim 30, wherein the visible light source includes a housing and the infrared mirror is located within the housing.
32. Apparatus according to any one of Claims 29 to 30, wherein the common path defines an imaginary cone from the visible light source to the object.
33. Apparatus according to any one of claims 20 to 32, wherein the infrared light source is arranged to project infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object by transmission through the object.
34. Apparatus according to any one of claims 18 to 33, wherein the infrared light source is arranged to project infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object through perforations in the object.
35. Apparatus according to any one of claims 18 to 34, wherein the infrared light source is arranged to project infrared light so that it will form part of the digital image of the object obtained by the image capture device when capturing an image of the object directly from the infrared source.
36. Apparatus according to any one of claims 18 to 35, wherein the apparatus is arranged to provide the infrared light in such a way so as to produce a pattern on the digital image formed by the image capture device when capturing an image.
37. Apparatus according to Claim 36, wherein the pattern comprises recognisable identification information.
38. Apparatus according to any one of Claims 18 to 34, wherein the object is a cinema projection screen.