JP2014048304A - Image display system and image processing device - Google Patents

Abstract

An image display system and an image processing apparatus capable of suppressing deterioration in image quality due to a Fresnel reflection component are provided.
An image display system 100 scatters a first linearly polarized light that vibrates in a first direction and transmits a second linearly polarized light that oscillates in a second direction orthogonal to the first direction. And an optical projection device 300 for projecting the first linearly polarized video light on the screen 200 to display an image, and an optical projection device 300 that is positioned on one side of the screen 200. An imaging device 400 that acquires a first image composed of first linearly polarized light and a second image composed of second linearly polarized light, and an image processing unit that performs image processing on the second image based on the first image. 1000.
[Selection] Figure 1

Description

  The present invention relates to an image display system and an image processing apparatus.

Due to the recent development of networks, people in remote places are increasingly conducting conferences (so-called video conferences) via networks. As a system used for such a video conference, a display photographing apparatus of Patent Document 1 is known.
The display photographing apparatus of Patent Document 1 has a display on which a partner's video is projected and a video camera provided on the back side of the display, and the video camera photographs a person on the front side of the display through the display. It is configured as follows. Here, since the display has a property of substantially transmitting a specific linearly polarized light, in Patent Document 1, a polarizing plate is provided on the front surface of the video camera, and only the specific linearly polarized light that transmits the display is a video camera. The person can be photographed through the display. As described above, by arranging the video camera on the back of the display, it is possible to capture an image in which the person's eyes match, so that the video conference can proceed without a sense of incongruity.
However, in such a configuration, a specific linearly polarized light component of the light (random polarized light) reflected by Fresnel on the back surface of the display passes through the polarizing plate and enters the video camera. For this reason, there is a problem that noise caused by the Fresnel reflection component is generated in the image data acquired by the video camera, and the image quality is deteriorated.

JP 2001-83497 A

  An object of the present invention is to provide an image display system and an image processing apparatus that can suppress a decrease in image quality due to a Fresnel reflection component.

Such an object is achieved by the present invention described below.
The image display system of the present invention scatters the first linearly polarized light that oscillates in the first direction, and allows the screen to take a scattering state that transmits the second linearly polarized light that oscillates in the second direction orthogonal to the first direction;
An optical projection device located on one side of the screen and projecting the first linearly polarized video light on the screen to display an image on the screen;
An imaging device that is located on one side of the screen and acquires a first image composed of the first linearly polarized light and a second image composed of the second linearly polarized light when the screen is in the scattering state;
An image processing unit that performs image processing on the second image based on the first image.
By adopting such a configuration, it is possible to remove the Fresnel reflection component, and it is possible to suppress deterioration in image quality due to the Fresnel reflection component.

In the image display system of the present invention, it is preferable that the image processing unit performs a background difference on the second image with the first image as a background image.
With such a configuration, the Fresnel reflection component can be removed by simple image processing.
In the image display system of the present invention, the screen can be in a transmission state that transmits the first linearly polarized light and the second linearly polarized light,
The imaging device acquires a third image consisting of the first linearly polarized light or the second linearly polarized light when the screen is in the transmissive state;
The image processing unit preferably corrects the color of the second image based on the third image.
With this configuration, the image processed by the image processing unit becomes a more natural image.

In the image display system of the present invention, the photographing device includes a photographing optical system into which light is incident, and
And a polarization controller that performs polarization control of the light incident on the photographing optical system.
With such a configuration, the imaging device can acquire the first image and the second image with a small number of parts.

In the image display system of the present invention, it is preferable that the polarization control unit includes a polarizer that passes linearly polarized light that vibrates in a predetermined direction, and a drive unit that changes the posture of the polarizer.
With such a configuration, the first image and the second image can be easily captured separately by rotating the polarizer by 90 ° by the driving unit.

In the image display system of the present invention, the deflection control unit can select a state having chirality and a state having no chirality, and a liquid crystal device,
It is preferable to include a polarizer that is provided between the liquid crystal device and the photographing optical system and allows linearly polarized light deflected in a predetermined direction to pass therethrough.
With such a configuration, the first image and the second image can be easily captured separately by controlling the driving of the liquid crystal device.

In the image display system of the present invention, it is preferable that the imaging device acquires the first image after startup before acquiring the second image.
By setting it as such a structure, the image process based on a 1st image can be performed about all the 2nd images acquired after starting.
In the image display system of the present invention, it is preferable that the photographing device acquires the first image at predetermined time intervals.
By adopting such a configuration, it is possible to cope with changes in the background, and it is possible to perform more accurate image processing on the second image.

In the image display system of the present invention, it is preferable that the screen has a polymer-dispersed liquid crystal layer in which a polymer is dispersed in liquid crystal molecules.
According to the screen having such a configuration, the scattering state and the transmission state can be easily switched.
In the image display system of the present invention, it is preferable that the screen is in the scattering state by applying an electric field to the polymer dispersed liquid crystal layer.
According to such a configuration, since the screen can be in a transmissive state (transparent state) when not in use, the feeling of pressure given by the screen can be reduced.

An image processing apparatus according to the present invention is disposed on one side of a screen that scatters first linearly polarized light that vibrates in a first direction and transmits second linearly polarized light that vibrates in a second direction orthogonal to the first direction. The second image including the second linearly polarized light acquired by the imaging device is subjected to image processing based on the first image including the first linearly polarized light acquired by the imaging device.
By adopting such a configuration, it is possible to remove the Fresnel reflection component, and it is possible to suppress deterioration in image quality due to the Fresnel reflection component.

1 is a schematic diagram of an image display system according to a first embodiment of the present invention. It is the schematic of the video conference using the image display system shown in FIG. It is sectional drawing (AA sectional view taken on the line in FIG. 1) of the screen which the image display system shown in FIG. 1 has. It is sectional drawing which shows the voltage application state of the screen shown in FIG. It is a figure which shows scattering of the image light which passes the screen shown in FIG. 3, (a) is a figure corresponding to the AA line cross section in FIG. 1, (b) is a BB line cross section in FIG. It is a corresponding figure. It is a figure which shows scattering of the image light which passes the screen shown in FIG. 3, (a) is a figure corresponding to the AA line cross section in FIG. 1, (b) is a BB line cross section in FIG. It is a corresponding figure. It is a graph which shows the screen transmittance | permeability of the linearly polarized light from which a polarization direction differs. It is a top view which shows the structure of the optical system of the optical projection device shown in FIG. It is a top view which shows the relationship between the orientation direction of the liquid crystal molecule contained in a screen, and the polarization direction of the image light irradiated to a screen. It is a block diagram of the imaging device which the image display system shown in FIG. 1 has. It is a figure for demonstrating the action | operation of the image display system shown in FIG. It is a figure for demonstrating the action | operation of the image display system shown in FIG. It is sectional drawing of the polarization control part with which the image display system concerning 2nd Embodiment of this invention is provided. It is sectional drawing explaining the drive of the liquid crystal device which the polarization control part shown in FIG. 13 has.

Hereinafter, an image display system and an image processing apparatus of the present invention will be described in detail based on preferred embodiments shown in the drawings.
<First Embodiment>
FIG. 1 is a schematic diagram of an image display system according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a video conference using the image display system shown in FIG. 3 is a cross-sectional view (cross-sectional view taken along line AA in FIG. 1) of the screen included in the image display system shown in FIG. 4 is a cross-sectional view showing a voltage application state of the screen shown in FIG. 5 and 6 are diagrams showing scattering of image light passing through the screen shown in FIG. 3, wherein (a) is a diagram corresponding to the cross section along line AA in FIG. 1, and (b) is in FIG. It is a figure corresponding to a BB line section. FIG. 7 is a graph showing screen transmittance of linearly polarized light having different polarization directions. FIG. 8 is a plan view showing the configuration of the optical system of the optical projection device shown in FIG. FIG. 9 is a plan view showing the relationship between the alignment direction of the liquid crystal molecules contained in the screen and the polarization direction of the image light irradiated on the screen. FIG. 10 is a configuration diagram of a photographing device included in the image display system shown in FIG. 11 and 12 are diagrams for explaining the operation of the image display system shown in FIG.

As shown in FIG. 1, the image display system 100 includes a screen 200, a light projection device 300, a photographing device 400, an image processing unit (image processing apparatus of the present invention) 1000, and a control unit 800. Yes.
Such an image display system 100 can be suitably used for a so-called video conference. When used in a video conference, for example, as shown in FIG. 2, image display systems 100 and 100 ′ are provided in two remote conference rooms R 1 and R 2, and these image display systems 100, 100 'is connected. The video of the person X captured by the imaging device 400 is transmitted to the image display system 100 ′ via the network N, and the video is displayed on the screen 200 ′ by the optical projection device 300 ′. On the contrary, the video of the person Y captured by the imaging device 400 ′ is transmitted to the image display system 100 via the network N, and the video is displayed on the screen 200 by the optical projection device 300. Note that the audio is acquired by, for example, microphones built in the video cameras 500 and 500 ′ and output from speakers (not shown) provided in the conference rooms R1 and R2. Further, the light projection devices 300 and 300 ′ project image light on the rear surface which is the opposite surface when the person X side and the person Y side of the screens 200 and 200 ′ are front surfaces. According to such a system, since the conference can be performed while viewing the other party's images (real-time images) displayed on the screens 200 and 200 ′, the video conference can be smoothly advanced.

Hereinafter, the image display system 100 will be described in detail. The image display system 100 ′ has the same configuration as the image display system 100.
(screen)
As shown in FIG. 3, the screen 200 is provided between a pair of transparent substrates 211 and 212, a pair of transparent electrodes 221 and 222, a pair of alignment films 231 and 232, and a pair of transparent substrates 211 and 212. And a polymer dispersed liquid crystal layer 250.

  The transparent substrates 211 and 212 have a function of supporting the transparent electrodes 221 and 222 and the alignment films 231 and 232. Further, the transparent substrate 211 is located on the back side of the screen 200 (the optical projection device 300 side), and the transparent substrate 212 is located on the front side of the screen 200 (the person X side). The constituent materials of the transparent substrates 211 and 212 are not particularly limited, and examples thereof include glass materials such as quartz glass and plastic materials such as polyethylene terephthalate. Among these, it is particularly preferable that it is made of a glass material such as quartz glass. As a result, it is possible to obtain a screen 200 that is less likely to warp, bend, or the like and that is more stable.

The transparent electrode 221 of the pair of transparent electrodes 221 and 222 is formed on the inner surface of the transparent substrate 211, and the transparent electrode 222 is formed on the inner surface of the transparent substrate 212. These transparent electrodes 221 and 222 have conductivity, and are made of, for example, indium tin oxide (ITO), indium oxide (IO), tin oxide (SnO ₂ ), or the like.

  The alignment film 231 of the pair of alignment films 231 and 232 is formed on the inner surface of the transparent electrode 221, and the alignment film 232 is formed on the inner surface of the transparent electrode 222. Further, the pair of alignment films 231 and 232 are formed so that a twist angle of a liquid crystal molecule 253 described later sandwiched between them is substantially 0 °. These alignment films 231 and 232 are obtained by, for example, performing an alignment process such as a rubbing process on a film made of polyimide, polyvinyl alcohol, or the like.

The polymer-dispersed liquid crystal layer 250 can switch between a transmission (transparent) state and a scattering state depending on the strength of an applied electric field. Such a polymer dispersed liquid crystal layer 250 includes PDLC (polymer dispersed liquid crystal) 251. The PDLC 251 includes liquid crystal molecules 253 and a polymer 252 dispersed in the liquid crystal molecules 253. The liquid crystal molecules 253 and the polymer 252 are aligned along the alignment directions A and B between the alignment films 231 and 232 in a voltage non-application state in which no voltage is applied between the pair of transparent electrodes 221 and 222, respectively. It has a predetermined tilt angle and is oriented in a predetermined direction.
In FIG. 3, the alignment direction of the liquid crystal molecules 253 on the alignment film 231 side is indicated by an arrow A, and the alignment direction of the liquid crystal molecules 253 on the alignment film 232 side is indicated by an arrow B. In the following, it is also referred to as an alignment direction A and an alignment direction B.

  Such a PDLC 251 can be formed by, for example, a mixture of a polymer precursor such as a liquid crystalline monomer and liquid crystal molecules. Specifically, the liquid crystal monomer is polymerized by irradiating the mixture with energy such as ultraviolet light while the mixture is aligned by the alignment films 231 and 232. Then, the liquid crystalline monomer is polymerized while maintaining the alignment, and becomes a polymer 252 having an alignment regulating force. The liquid crystal molecules 253 are phase-separated from the polymer 252 and are aligned by the alignment regulating force of the polymer 252.

  The polymer precursor is not particularly limited as long as it is dissolved in the liquid crystal molecules 253 and the mixed solution has liquid crystallinity, and examples thereof include those in which a benzene skeleton, preferably a biphenyl skeleton is introduced into the polymer. . Moreover, even if it does not have a benzene skeleton, any polymer that aligns with the liquid crystal molecules 253 can be used similarly. Specific examples of the polymer 252 and the polymer precursor include, for example, methacrylic acid ester or acrylic acid ester of biphenylmethanol or naphthol, or derivatives of these compounds. Moreover, you may mix and use the methacrylic ester or acrylic ester derivative of biphenol with these. Moreover, (alpha) -methylstyrene, an epoxy resin, etc. can also be used as another example.

  On the other hand, the liquid crystal molecules 253 only have to have refractive index anisotropy and dielectric anisotropy, and can be appropriately selected from known liquid crystal materials. As the liquid crystal molecules 253, the refractive index in the major axis direction is substantially equal to the refractive index in the major axis direction of the polymer 252 and the refractive index in the minor axis direction is the refractive index in the minor axis direction of the polymer 252. Further, a material whose refractive index in the minor axis direction is sufficiently different from the refractive index in the major axis direction of the polymer 252 is used.

The PDLC 251 of this embodiment is a reverse type. Therefore, the polymer-dispersed liquid crystal layer 250 is in a transmissive state having optical transparency when no voltage is applied between the pair of transparent electrodes 221 and 222, and the voltage between the pair of transparent electrodes 221 and 222 is reduced. In a voltage application state in which is applied, a scattering state having light scattering properties is obtained.
More specifically, in the voltage non-applied state, the refractive index is continuous between the liquid crystal molecules 253 and the polymer 252 and light incident on the PDLC 251 is emitted without being diffused, and is in a transmissive state. Become. On the other hand, in the voltage application state, as shown in FIG. 4, the azimuth angle of the polymer 252 does not change, whereas the azimuth angle of the liquid crystal molecules 253 changes according to the electric field. When the refractive index changes discontinuously with the liquid crystal molecules 253, the incident light is scattered and emitted to enter a light scattering state.
The “electric field non-generation state” is applied not only in a state where no electric field acts on the polymer dispersed liquid crystal layer 250 but also in a state where an electric field is generated between the pair of transparent electrodes 221 and 222. This includes the case where a voltage weaker than the voltage is applied and an electric field having a lower intensity than the electric field generation state is generated.

  According to this screen 200, when the screen 200 is not used, the screen 200 can be kept transparent. Therefore, for example, when the screen 200 is used in a living space, the feeling of pressure given by the screen 200 can be reduced. Further, as described above, since the screen 200 uses the reverse type PDLC 251, the time during which an image is displayed on the screen 200 (that is, the time in the scattering state) is the time during which no image is displayed on the screen 200 (that is, the time). It is preferably used for applications shorter than the transmission state time). By using such a method, power saving driving of the image display system 100 becomes possible.

In the screen 200 having such a configuration, the linearly polarized light (first linearly polarized light) L1 that vibrates in a direction (first direction) parallel to the alignment direction A of the liquid crystal molecules 253 located on the back side of the screen 200 in the diffusion state. And linearly polarized light (second linearly polarized light) L2 that vibrates in a direction orthogonal to the orientation direction A (second direction) is transmitted.
More specifically, in a voltage application state, light incident on the polymer dispersed liquid crystal layer 250 from the back side of the screen 200 passes through the polymer 252 and the liquid crystal molecules 253 alternately. At this time, the linearly polarized light L1 passes through the polymer 252 in the minor axis direction and the liquid crystal molecules 253 in the major axis direction, as shown in FIGS. 5 (a) and 5 (b). As described above, since the refractive index in the minor axis direction of the polymer 252 and the refractive index in the major axis direction of the liquid crystal molecules 253 are different, the linearly polarized light L1 is generated at the interface between the polymer 252 and the liquid crystal molecules 253. Scattered. On the other hand, as shown in FIGS. 6A and 6B, the linearly polarized light L2 passes the polymer 252 in the minor axis direction and the liquid crystal molecules 253 in the minor axis direction. As described above, since the refractive index in the minor axis direction of the polymer 252 and the refractive index in the minor axis direction of the liquid crystal molecules 253 are substantially equal, the linearly polarized light L2 is almost at the interface between the polymer 252 and the liquid crystal molecules 253. The light passes through the polymer dispersed liquid crystal layer 250 as it is without being scattered.
FIG. 7 shows an example of the transmittance of the linearly polarized light L1 and L2. As is clear from FIG. 7, the linearly polarized light L <b> 1 hardly transmits through the polymer dispersed liquid crystal layer 250 and is mostly scattered within the polymer dispersed liquid crystal layer 250. On the other hand, the linearly polarized light L 2 hardly scatters in the polymer dispersed liquid crystal layer 250, and most of the linearly polarized light L 2 is transmitted through the polymer dispersed liquid crystal layer 250.

(Light projection device)
The light projection device 300 includes a projector 600 and a polarization controller 700 (see FIG. 1).
As shown in FIG. 8, the projector 600 includes a light source device 620, a uniform illumination optical system 630, a light modulation device 640, and a projection optical system 650. Such a projector 600 forms a light image by modulating the light emitted from the light source device 620 by the light modulation device 640 according to the given image information, and projects the light image into a projection optical system (projection lens group). ) An optical device for enlarging and projecting from 650 onto the screen 200.

The light source device 620 includes an ultra-high pressure mercury lamp 621 that is a light source and a reflector 622. In such a configuration, the light emitted from the extra-high pressure mercury lamp 621 is reflected by the reflector 622 and converged to the front side. In addition, as a light source, you may employ | adopt not only an ultrahigh pressure mercury lamp but a metal halide lamp etc., for example.
The uniform illumination optical system 630 includes a rod integrator 631, a color wheel 632, a relay lens group 633, and a reflection mirror 634. In such a uniform illumination optical system 630, the light beam emitted from the light source device 620 passes through the color wheel 632 and then enters the rod integrator 631 at an angle.

  The color wheel 632 is rotatably provided by a driving source such as a motor (not shown). Further, the color wheel 632 is formed with a filter surface 632a facing a port formed at the incident side end of the rod integrator 631, and the filter surface 632a has R (red), G (green), B (blue) three-color filters are formed side by side in the circumferential direction across an area. The color wheel 632 may be provided on the emission side of the rod integrator 631.

  The light beam incident on the color wheel 632 is color-separated in time series into three colors of red (R) light, green (G) light, and blue (B) light by the filter surface 632a. The separation into the three colors R, G, and B is performed at a frequency faster than the frame frequency of the image displayed on the screen 200. By performing color separation at such a frequency, a full color image can be displayed on the screen 200.

The light (R light, G light, B light) that has passed through the color wheel 632 is introduced into the inside of the incident port of the rod integrator 631. The light introduced into the rod integrator 631 is reflected a plurality of times in the rod integrator 631, thereby ensuring a uniform illuminance on the exit surface of the rod integrator 631. Therefore, the light emitted from the emission port of the rod integrator 631 has a uniform illumination distribution.
The light emitted from the rod integrator 631 enters the light modulation device 640 as uniform illumination light via the relay lens group 633 and the reflection mirror 634.

  The light modulation device 640 includes a substrate 641 and a plurality of light modulation elements 642 arranged on the substrate (for example, DMD (Digital Micromirror Device: “DMD” is a registered trademark of Texas Instruments Incorporated, USA). The plurality of light modulation elements 642 are arranged in a matrix on the substrate 641. The number of light modulation elements 642 is not particularly limited, and in the projector 600, one light modulation element 642 is provided. Therefore, the light modulation elements 642 are arranged in the number of pixels, for example, horizontal × vertical = 1280 × 1024, 640 × 480.

Each light modulation element 642 has a movable mirror for reflecting an incident light beam, and this movable mirror has an ON state in which the reflected light is guided to the projection optical system 650 and an inclination with respect to the ON state. In contrast, the posture changes to an OFF state in which the reflected light is guided to an absorber (not shown).
The light modulation device 640 forms a predetermined light image by independently switching ON / OFF states of each light modulation element 642 based on the image information given from the control unit 800. The formed optical image is incident on the projection optical system 650. The projection optical system 650 includes a projection lens 651 and emits an optical image guided to the projection optical system 650 as video light L.

  The image light L emitted from the projection optical system 650 passes through the polarization controller 700. The polarization controller 700 is a polarizer that converts the image light L, which is randomly polarized light, into image light L ′ that is linearly polarized light in a predetermined vibration direction. Such a polarization control unit 700 is not particularly limited as long as the above effects can be exhibited, and for example, a known device such as a wire grid array or a liquid crystal device can be used.

As shown in FIG. 9, the polarization direction C of the image light L ′ that has been linearly polarized by the polarization controller 700 is parallel to the alignment direction A of the liquid crystal molecules 253. By making the orientation direction A and the polarization direction C parallel to each other, the video light L ′ can be efficiently scattered on the screen 200 for the reason described above. Therefore, the generation of bright spots on the screen 200 can be effectively suppressed, and the quality of the image displayed on the screen 200 is increased.
The “parallel” includes not only the case where the alignment direction A and the polarization direction C are parallel, but also the case where the polarization direction C is slightly inclined with respect to the alignment direction A. Specifically, the case where the angle between the orientation direction A and the polarization direction C is about 10 ° or less in a plan view of the screen 200 is included. If it is in such a range, a sufficient effect can be exhibited.

The optical projection device 300 has been described above. In such an optical projection device 300, the polarization controller 700 is located between the projector 600 and the screen 200. In addition, the polarization controller 700 is provided separately from the projector 600. By adopting such a configuration for the optical projection device 300, the orientation of the polarization controller 700 relative to the screen 200 can be maintained at a predetermined orientation regardless of the orientation of the projector 600. Therefore, the polarization controller 700 can always obtain the image light L ′ in which the polarization direction C coincides with the alignment direction A.
The light projection device 300 is not particularly limited as long as the image light L ′ whose polarization direction matches the alignment direction A can be emitted. For example, the polarization controller 700 may be built in the projector 600 and may be disposed between the light modulation device 640 and the projection optical system 650. Various liquid crystal projectors (LCD) may be used.

(Shooting device)
As illustrated in FIG. 10, the photographing device 400 includes a video camera 500 and a polarization controller 900 that controls the polarization of light incident on the video camera 500.
The video camera 500 includes an imaging optical system (imaging lens group) 510, an imaging unit 520 (for example, an imaging element such as a CCD or CMOS) that converts an optical image formed by the imaging optical system 510 into an electrical signal, and imaging. An A / D conversion unit 530 that converts the output of the unit 520 into a digital signal, and an arithmetic unit 540 that converts the digital signal output from the A / D conversion unit 530 into image data by performing image processing or compression arithmetic processing. The transmission unit 550 transmits the image data generated by the calculation unit 540, and the storage unit (storage medium such as SSD or HDD) (not shown) that stores the image data and the like.

  Such a video camera 500 is provided on the back side of the screen 200 (see FIG. 1). As shown in FIGS. 1 and 2, the video camera 500 is arranged to face the person X through the screen 200, and the person X is viewing the person Y reflected on the screen 200. Are preferably arranged so that their lines of sight coincide. An image captured by the video camera 500 having such an arrangement is an image in which the line of sight of the person X matches. Therefore, since the person Y can hold a video conference in the state where the person X is projected on the screen 200 ′ and eyes are present, a more realistic conference is possible.

  Returning to FIG. 10, the polarization controller 900 is attached to the front surface of the photographing optical system 510 of the video camera 500. The polarization control unit 900 includes a polarizer 910 such as a wire grid array, and a drive unit 920 that rotates the polarizer 910 by 90 ° around the optical axis. In such a polarization control unit 900, the polarization control of light incident on the photographing optical system 510 can be easily performed by rotating the polarizer 910 by the driving unit 920. Specifically, by setting the polarizer 910 to a predetermined position (first state), the light passing through the polarizer 910 can be changed to linearly polarized light L3 that vibrates in a direction parallel to the alignment direction A. By setting 910 to a state rotated 90 ° from the first state (second state), light passing through the polarizer 910 can be made into linearly polarized light L4 that oscillates in a direction orthogonal to the orientation direction A. .

(Control part)
As shown in FIGS. 1 and 2, the control unit 800 is built in, for example, a personal computer, and includes a light projection device control unit 810, a screen control unit 820, a photographing device control unit 840, and an image data communication unit. 830.
The image data communication unit 830 transmits the image data processed by the image processing unit 1000 to the image display system 100 ′ via the network N. Further, the image data communication unit 830 receives the image data I ′ generated by the image display system 100 ′ via the network N. The image data I ′ is sent from the light projection device controller 810 to the light projection device 300 (projector 600), and the light projection device 300 emits video light L ′ based on the sent image data.

  The screen control unit 820 controls the driving of the screen 200 in correspondence with the transmission of the image data I ′ to the projector 600. Specifically, the screen control unit 820 sets the screen 200 in a transmissive state when the image data I ′ is not output from the light projection device control unit 810 to the projector 600. On the contrary, the screen control unit 820 causes the screen 200 to be in a scattering state when the image data I ′ is output from the light projection device control unit 810 to the projector 600. Further, when acquiring image data G1, G2, and G3 described later, the screen control unit 820 controls the state of the screen 200 so as to meet the acquisition conditions.

(Image processing unit)
The image processing unit 1000 has a function of image processing image data acquired by the video camera 500. Hereinafter, this image processing method will be described in detail. For convenience of explanation, as shown in FIG. 11, a background 2000 including a foliage plant 2100 exists on the back of the person X, and the back of the video camera 500 has a back. A case where the background 3000 including the forehead 3100 exists will be described.

First, the video camera 500 acquires image data G1 when the screen 200 is in a transmissive state. Specifically, the calculation unit 540 generates image data (third image) G1 based on the electrical signal from the imaging unit 520. As illustrated in FIG. 12A, the image data G <b> 1 is image data in which a person X and a background 2000 over the screen 200 are combined with a background 3000 that is Fresnel-reflected on the back of the screen 200. As will be described later, the image data G1 is image data for correction used as a reference for color correction of the image data G3 ′ after the background difference is performed. Such image data G1 is stored in the image processing unit 1000.
When acquiring the image data G1, the light guided from the polarization controller 900 to the photographing optical system 510 may be either linearly polarized light L3 or L4. That is, the state of the polarization controller 900 does not matter.

  Next, the polarizer 910 is rotated as necessary so that the linearly polarized light L3 passes through the polarizer 910. Then, the image data (first image) G2 of the linearly polarized light L3 when the screen 200 is in the scattering state is acquired by the video camera 500. The linearly polarized light L3 is an opaque component for the screen 200 because its polarization direction is parallel to the alignment direction A of the liquid crystal molecules 253. Therefore, as shown in FIG. 12B, the image data G2 is image data in which only the background 3000 reflected by Fresnel reflection on the back surface of the screen 200 is reflected without the person X and the background 2000 passing through the screen 200. As will be described later, the image data G2 is image data for correction used as a background image for background difference. The image data G2 is stored in the image processing unit 1000.

  Next, the screen 200 is set in a scattering state, and the image light L ′ based on the image data I ′ is emitted from the light projection device 300. Thereby, the video of the person Y is displayed on the screen 200 in real time. Further, the polarizer 910 is rotated so that the linearly polarized light L4 passes through the polarizer 910, and the video camera 500 acquires image data (second image) G3 of the linearly polarized light L4. The linearly polarized light L4 is a transmission component for the screen 200 because its polarization direction is orthogonal to the alignment direction A of the liquid crystal molecules 253. Therefore, according to the linearly polarized light L4, it is possible to image the person X and the background 2000 over the screen 200 even when the screen 200 is in a scattering state. Therefore, as shown in FIG. 12C, the image data G3 is image data in which the person X and the background 2000 over the screen 200 and the background 3000 reflected by Fresnel reflection on the back surface of the screen 200 are combined. Such image data G3 is sent to the image processing unit 1000.

  The image processing unit 1000 uses the stored image data G2 as background image data, performs background difference extraction for an object that does not exist in the image data G2 with respect to the transmitted image data G3, and creates new image data G3 ′. Is generated. In this embodiment, the image data G2 includes a background 3000, and the image data G3 includes a person X, a background 2000, and a background 3000. Therefore, as shown in FIG. 12D, the person X and the background 2000 other than the background 3000 are extracted from the image data G3 by the background difference, and this becomes the image data G3 '. The image data G3 'is clear image data from which the Fresnel reflection component is removed.

  Here, as described above, the image data G3 is image data of linearly polarized light L4. The linearly polarized light L4 is a transmission component for the screen 200, but is slightly scattered when passing through the screen 200 (see L2 in FIG. 7). Therefore, the image data G3 is an image in which the contrast is slightly lowered because the above-described slight scattering components are superimposed, and the image data G3 'generated from the image data G3 is also an image in which the contrast is slightly lowered. Therefore, the image processing unit 1000 performs processing for increasing the contrast of the image data G3 '. For example, the image processing unit 1000 performs a histogram expansion process on the image data G3 'to increase the contrast by widening the density distribution of the image data G3'.

Further, the image processing unit 1000 performs color correction on the image data G3 ′. In this case, the image data G1 acquired when the screen 200 is in the transmissive state is used as a reference. The image acquired when the screen 200 is in the transmissive state is clearer and more natural than the image acquired when the screen 200 is in the scattering state. Therefore, effective color correction can be performed by using such image data G1 as a reference. The color correction can be performed, for example, by correcting the saturation, hue, and the like so that an arbitrary pixel included in the image data G3 ′ has the same color as the corresponding pixel included in the image data G1. By performing such processing, the image data G3 ′ becomes clearer and more natural.
The image data G3 ′ thus generated is transmitted to the control unit 800, and is transmitted from the image data communication unit 830 of the control unit 800 to the image display system 100 ′ via the network N.

  For example, the video camera 500 continuously acquires the image data G3 at about 30 to 60 frames / second, the acquired image data G3 is processed by the image processing unit 1000, and the generated image data G3 ′ is converted into the image display system 100 ′. Can be displayed on the screen 200 ′ of the image display system 100 ′ so that a smooth moving image with the person X as a subject can be displayed.

As described above, according to the image display system 100, the clear image data G3 ′ from which the Fresnel reflection component (background 2000) is removed can be generated, and a video conference can be performed with a clear image. Therefore, the video conference can proceed more smoothly and without stress.
In addition, the timing which acquires image data G1 and G2 is not specifically limited. For example, the image data G1 and G2 may be acquired first (before acquiring the image data G3) after starting the video camera 500. In this case, until the image display system 100 stops, image data G3 ′ is generated from the image data G3 based on the first acquired image data G1 and G2. Further, for example, the image data G1 and G2 may be acquired and updated at predetermined time intervals (for example, every 1 minute or 5 minutes). In this way, it is possible to cope with changes in the surroundings such as the background 2000 and 3000 changing during the meeting, and the lighting (including sunlight) changing, and the quality of the image data G3 ′ is degraded. Can be prevented. Further, the image data G1 and G2 may be manually acquired by the user.

Second Embodiment
Next, a second embodiment of the image display system of the present invention will be described.
FIG. 13 is a cross-sectional view of the polarization controller provided in the image display system according to the second embodiment of the present invention. FIG. 14 is a cross-sectional view illustrating driving of the liquid crystal device included in the polarization controller shown in FIG.

Hereinafter, the image display system according to the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The image display system according to the second embodiment of the present invention is the same as the first embodiment described above except that the configuration of the polarization control element is different. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment mentioned above.

As illustrated in FIG. 13, the polarization control unit 900A includes a polarizer 910 and a liquid crystal device 930 provided in front of the polarizer 910 (on the screen 200 side).
The liquid crystal device 930 uses twisted nematic liquid crystal. Such a liquid crystal device 930 includes a pair of transparent substrates 941 and 942, a pair of transparent electrodes 951 and 952, a pair of alignment films 961 and 962, and a liquid crystal layer provided between the pair of transparent substrates 941 and 942. 970. In addition, the alignment film 962 positioned on the polarizer 910 side of the pair of alignment films 961 and 962 is disposed in accordance with the direction of the polarizer 910 and the direction is shifted by 90 ° with respect to the alignment film 961. Has been. The liquid crystal molecules 971 included in the liquid crystal layer 970 are aligned along the direction of the alignment films 961 and 962 on the alignment films 961 and 962 side, and are twisted by 90 ° as a whole.

  As shown in FIG. 14A, the liquid crystal layer 970 has chirality when no voltage is applied between the pair of transparent electrodes 951 and 952. Therefore, natural light (random polarization) incident on the liquid crystal device 930 rotates 90 ° while passing through the liquid crystal layer 970. On the other hand, as shown in FIG. 14B, the chirality of the liquid crystal layer 970 is lost in a voltage application state in which a voltage is applied between the pair of transparent electrodes 951 and 952. Therefore, natural light (random polarization) incident on the liquid crystal device 930 passes through the liquid crystal layer 970 without rotating.

  According to the polarization controller 900A, by selecting the voltage non-application state or the voltage application state, the polarization direction before entering the liquid crystal device 930 passes the linearly polarized light L3 parallel to the alignment direction A of the liquid crystal molecules 253. And a state where the polarization direction before entering the liquid crystal device 930 passes the linearly polarized light L4 orthogonal to the alignment direction A of the liquid crystal molecules 253 can be selected.

  Since such a polarization control unit 900A electrically switches linearly polarized light that passes through the polarizer 910, for example, like the polarization control unit 900 of the first embodiment described above, mechanically passes through the polarizer 910. Compared with the configuration for switching the linearly polarized light, the switching can be performed in a shorter time. Therefore, in this embodiment, it is preferable to operate the imaging device 400 as follows.

  That is, in this embodiment, the video camera 500 acquires the image data G2 of the linearly polarized light L3 and the image data G3 of the linearly polarized light L4 alternately and continuously. Then, the image processing unit 1000 uses the predetermined image data G2 as a background image, and performs a background difference on the image data G3 acquired next to the image data G2. According to such a method, the background difference of each image data G3 can be performed based on the image data G2 acquired immediately before. Therefore, for example, even when there is a moving object (for example, a human, a machine, or the like) in the background 3000, or when such a moving object crosses the background 3000, the Fresnel reflection component is more accurately obtained from the image data G3. Can be generated.

Note that although a device using twisted nematic liquid crystal is used as the liquid crystal device 930, the configuration of the liquid crystal device 930 is not particularly limited as long as the same effect can be exhibited. For example, it may be a vertical alignment type liquid crystal device in which the alignment is controlled.
Also according to the second embodiment, the same effects as those of the first embodiment described above can be obtained.

The image display system and the image processing apparatus of the present invention have been described based on the illustrated embodiment. However, the image display system of the present invention is not limited to this, and the configuration of each unit has the same function. Can be replaced with any structure having Further, the image display system of the present invention may appropriately combine the above-described embodiments.
In the above-described embodiment, the reverse type screen is used. However, a normal type screen, that is, a screen that is in a scattering state in a voltage non-application state and in a transmission state in a voltage application state may be used.
In the above-described embodiment, the configuration in which the image processing unit exists independently has been described. However, the image processing unit may be built in, for example, a video camera or built in the control unit. Also good.

  DESCRIPTION OF SYMBOLS 100, 100 '... Image display system 200, 200' ... Screen 211, 212 ... Transparent substrate 221, 222 ... Transparent electrode 231, 232 ... Alignment film 250 ... Polymer dispersion type liquid crystal layer 251 ... PDLC 252 ... Polymer 253 ... Liquid crystal Molecule 300, 300 '... light projection device 400, 400' ... imaging device 500 ... video camera 510 ... imaging optical system 520 ... imaging unit 530 ... A / D conversion unit 540 ... calculation unit 550 ... transmission unit 600 ... projector 620 ... light source Device 621... High pressure mercury lamp 622. Reflector 630. Uniform illumination optical system 631. Rod integrator 632. Color wheel 632 a. Element 650 ... Projection optical system 651 ... Projection lens 700 ... Polarization control unit 800, 800 '... Control unit 810 ... Optical projection device control unit 820 ... Screen control unit 830 ... Image data communication unit 840 ... Imaging device control unit 900, 900A ... Polarization controller 910 ... Polarizer 920 ... Drive part 930 ... Liquid crystal device 941, 942 ... Transparent substrate 951, 952 ... Transparent electrode 961, 962 ... Alignment film 970 ... Liquid crystal layer 971 ... Liquid crystal molecule 1000, 1000 '... Image processor 2000 ... Background 2100 ... Foliage plant 3000 ... Background 3100 ... Forehead G1, G2, G3, G3 '... Image data R1, R2 ... Conference room L, L' ... Video light L1, L2, L3, L4 ... Linear polarization N ... Network X , Y ... person

Claims (11)

A screen capable of scattering a first linearly polarized light oscillating in a first direction and transmitting a second linearly polarized light oscillating in a second direction orthogonal to the first direction;
An optical projection device located on one side of the screen and projecting the first linearly polarized video light on the screen to display an image on the screen;
An imaging device that is located on one side of the screen and acquires a first image composed of the first linearly polarized light and a second image composed of the second linearly polarized light when the screen is in the scattering state;
An image display system, comprising: an image processing unit that performs image processing on the second image based on the first image.   The image display system according to claim 1, wherein the image processing unit performs a background difference on the second image using the first image as a background image. The screen may be in a transmission state that transmits the first linearly polarized light and the second linearly polarized light,
The imaging device acquires a third image consisting of the first linearly polarized light or the second linearly polarized light when the screen is in the transmissive state;
The image display system according to claim 1, wherein the image processing unit performs color correction on the second image based on the third image. The photographing device includes a photographing optical system in which light is incident;
The image display system according to claim 1, further comprising: a polarization control unit that performs polarization control of the light incident on the photographing optical system.   The image display system according to claim 4, wherein the polarization control unit includes a polarizer that passes linearly polarized light that vibrates in a predetermined direction, and a drive unit that changes the attitude of the polarizer. The deflection control unit is a liquid crystal device capable of selecting a state having chirality and a state having no chirality, and
The image display system according to claim 4, further comprising a polarizer that is provided between the liquid crystal device and the photographing optical system and allows linearly polarized light deflected in a predetermined direction to pass therethrough.   The image display system according to claim 1, wherein the imaging device acquires the first image after acquisition and before acquiring the second image.   The image display system according to claim 1, wherein the photographing device acquires the first image at predetermined time intervals.   The image display system according to claim 1, wherein the screen includes a polymer-dispersed liquid crystal layer in which a polymer is dispersed in liquid crystal molecules.   The image display system according to claim 9, wherein the screen is in the scattering state by applying an electric field to the polymer-dispersed liquid crystal layer.   The first linearly polarized light that oscillates in a first direction is scattered, and the second linearly polarized light that oscillates in a second direction orthogonal to the first direction is transmitted through the imaging device disposed on one side of the screen. An image processing apparatus that performs image processing on a second image composed of two linearly polarized light based on the first image composed of the first linearly polarized light acquired by the photographing device.

Images