Video display device, video display control device, and program

Abstract

This video display device comprises: a viewpoint location limitation unit that has an optical element for limiting a first viewpoint location and a second viewpoint location; an image display unit that has a display surface including a plurality of pixels and displays a first image and a second image on the display surface; and a control unit that allocates, to each of the pixels included in the display surface, an image value based on at least the first image or the second image. The control unit: allocates a pixel value based on the first image to at least a part of the pixels which are observed from the first viewpoint location through the optical element; allocates a pixel value based on the second image to at least a part of the pixels which are observed from the second viewpoint location through the optical element; and allocates, to at least a part of the pixels which are observed from the first viewpoint location through the optical element and are also observed from the second viewpoint location through the optical element, a synthesized pixel value obtained by synthesizing the pixel value based on the first image and the pixel value based on the second image at a prescribed synthesis ratio.

Description

Video display device, video display control device, and program

[0001] This application claims priority to Japanese Patent Application No. 2023-172530, filed on October 4, 2023, the contents of which are incorporated herein by reference.

[0002] In the field of naked-eye stereoscopic technology, there is known a display device that enables the viewing of a stereoscopic image by separately providing a right-eye image and a left-eye image to the left and right eyes of a viewer. For example, Patent Document 1 discloses a method of displaying images from three or more viewpoints, restricting the area in which each image can be viewed with a parallax barrier, and enabling the viewing of a stereoscopic image over a wider range than with a two-viewpoint method, even when moving left and right or forward and backward.

[0003] Japanese Patent Application Laid-Open No. 2003-158752

[0004] In naked-eye stereoscopic vision, there are inverted viewing areas where 3D images cannot be observed. Therefore, if you move left or right more than the number of viewpoints and enter an inverted viewing area, you will no longer be able to observe the 3D image. Furthermore, if you move forward or backward more than a certain distance, an inverted viewing area will appear on the screen, making it impossible to observe a portion of the 3D image on the screen. It is required that the entire screen can be displayed without any inverted viewing area, regardless of the observer's position.

[0005] The present invention has been made in view of the above points, and provides an image display device, an image display control device, and a program that can display an image without creating a pseudoscopic area across the entire screen, regardless of the position of the viewer.

[0006] The present invention has been made to solve the above-mentioned problems, and one aspect of the present invention is a video display device comprising: a viewpoint position restriction unit having an optical element that restricts a first viewpoint position at which a first viewpoint is located and a second viewpoint position at which a second viewpoint is located, from which a first image and a second image can be viewed; an image display unit having a display surface including a plurality of pixels and displaying the first image and the second image on the display surface; and a control unit that assigns image values ​​based on at least the first image and the second image to each pixel included on the display surface, wherein the control unit assigns pixel values ​​based on the first image to at least a portion of pixels observed from the first viewpoint position through the optical element, assigns pixel values ​​based on the second image to at least a portion of pixels observed from the second viewpoint position through the optical element, and assigns a composite pixel value obtained by combining pixel values ​​based on the first image and pixel values ​​based on the second image at a predetermined combination ratio to at least a portion of pixels observed from the first viewpoint position through the optical element and observed from the second viewpoint position through the optical element.

[0007] Furthermore, one aspect of the present invention is a video display control device that is provided as the control unit in a video display device that includes: a viewpoint position restriction unit having an optical element that restricts a first viewpoint position at which a first viewpoint is located and a second viewpoint position at which a second viewpoint is located, from which the first image and the second image can be viewed; an image display unit having a display surface including a plurality of pixels and displaying the first image and the second image on the display surface; and a control unit that assigns image values ​​based on at least the first image and the second image to each pixel included in the display surface, wherein the video display control device assigns pixel values ​​based on the first image to at least a portion of the pixels observed from the first viewpoint position through the optical element, assigns pixel values ​​based on the second image to at least a portion of the pixels observed from the second viewpoint position through the optical element, and assigns a composite pixel value obtained by combining the pixel values ​​based on the first image and the pixel values ​​based on the second image at a predetermined combination ratio to at least a portion of the pixels observed from the first viewpoint position through the optical element and from the second viewpoint position through the optical element.

[0008] Another aspect of the present invention is a program for causing a computer as the control unit provided in a video display device including: a viewpoint position restriction unit having an optical element that restricts a first viewpoint position at which a first viewpoint is located and a second viewpoint position at which a second viewpoint is located, from which a first image and a second image are viewable, respectively; an image display unit having a display surface including a plurality of pixels and displaying the first image and the second image on the display surface; and a control unit that assigns image values ​​based on at least the first image and the second image to each pixel included in the display surface, to execute the following steps: assigning pixel values ​​based on the first image to at least a portion of pixels observed from the first viewpoint position through the optical element; assigning pixel values ​​based on the second image to at least a portion of pixels observed from the second viewpoint position through the optical element; and assigning composite pixel values ​​obtained by combining pixel values ​​based on the first image and pixel values ​​based on the second image at a predetermined combination ratio to at least a portion of pixels observed from the first viewpoint position through the optical element and observed from the second viewpoint position through the optical element.

[0009] According to the present invention, regardless of the position of the viewer, it is possible to display an image without generating any pseudoscopic area on the entire screen.

[0010] 1 is a diagram showing an example of the configuration of a stereoscopic image display device 1 according to a first embodiment of the present invention. FIG. 2 is a diagram showing an example of the functional configuration of the stereoscopic image display device 1 according to the first embodiment of the present invention. FIG. 3 is a flowchart showing an example of the procedure of a design stage of a control method for the stereoscopic image display device 1 according to the first embodiment of the present invention. FIG. 4 is a diagram showing an example of a barrier end face overlap pixel range according to the first embodiment of the present invention. FIG. 5 is a diagram showing an example of a state of pixels observed by the right eye ER1 and the left eye EL1 according to the first embodiment of the present invention. FIG. 6 is a diagram showing an example of a crosstalk calculation according to the first embodiment of the present invention. FIG. 7 is a diagram showing an example of a luminance value of a composite pixel according to the first embodiment of the present invention. FIG. 8 is a flowchart showing an example of the procedure of an operation stage of a control method for the stereoscopic image display device 1 according to the first embodiment of the present invention. FIG. 9 is a diagram showing an example of a state in which an area observed by the right eye ER1 and an area observed by the left eye EL1 overlap when the observer P1 according to the first embodiment of the present invention moves further rearward than the position shown in FIG. 6. FIG. 10 is a diagram showing an example of a composite pixel value according to the first embodiment of the present invention. FIG. 11 is a diagram showing an example of a state in which an area observed by the right eye ER1 and an area observed by the left eye EL1 overlap more when the observer P1 according to the first embodiment of the present invention moves further rearward than the position shown in FIG. 9. FIG. 12 is a diagram showing an example of a composite pixel value according to the first embodiment of the present invention. 16 is a diagram showing an example of a state in which the overlap between the region observed by the right eye ER1 and the region observed by the left eye EL1 becomes larger when the observer P1 according to the first embodiment of the present invention moves further rearward from the position shown in FIG. 11 . FIG. 17 is a diagram showing an example of a composite pixel value according to the first embodiment of the present invention. FIG. 18 is a diagram showing an example of a state in which the region observed by the right eye ER1 and the region observed by the left eye EL1 become overlapped when the observer P1 according to the first embodiment of the present invention moves forward from the position shown in FIG. 4 . FIG. 19 is a diagram showing an example of a state in which the minimum overlap between the region observed by the right eye ER1 and the region observed by the left eye EL1 becomes minimum when the observer P1 according to the modified embodiment of the first embodiment of the present invention moves left or right from the position shown in FIG. 16 .17 is a diagram showing an example of a state in which the left-eye image ML1 according to a modified example of the first embodiment of the present invention has moved by one pixel in the left-right direction from the position shown in FIG. 17 , resulting in minimal overlap between the region observed by the right eye ER1 and the region observed by the left eye EL1. FIG. 18 is a diagram showing an example of a state in which the region observed by the right eye ER1 and the region observed by the left eye EL1 have maximized overlap when the viewer P1 according to the modified example of the first embodiment of the present invention has moved left-right from the position shown in FIG. 18 . FIG. 19 is a diagram showing an example of a state in which the right-eye observation region and the left-eye observation region are evenly aligned on a display surface 20 according to a second embodiment of the present invention. FIG. 19 is a diagram showing an example of a state in which the viewer P1 according to the second embodiment of the present invention has moved rearward from the position shown in FIG. 20 , resulting in overlap between the right-eye observation region and the left-eye observation region. FIG. 20 is a flowchart showing an example of the procedure of the operation stage of a control method for a stereoscopic video display device 1 according to a third embodiment of the present invention. FIG. 21 is a diagram showing an example of a display surface 20 in which the display boundary between the right-eye image MR1 and the left-eye image ML1 has been determined based on the position of the viewpoint according to the third embodiment of the present invention. FIG. 11 is a diagram illustrating an example of a composite pixel value according to the third embodiment of the present invention.

[0011] (First Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of a stereoscopic image display device 1 according to this embodiment. The stereoscopic image display device 1 includes a display 2, an optical element 3, a backlight 4, a controller 5, a camera 6, and an image processing circuit 7. In the following description, three-dimensional Cartesian coordinates defined by the X-axis, Y-axis, and Z-axis shown in FIG. 1 will be used as appropriate. The X-axis, Y-axis, and Z-axis form a right-handed system.

[0012] The display 2 has a display surface 20. As an example, the display 2 is a liquid crystal display. The display 2 displays a first image and a second image on the display surface 20. In this embodiment, as an example, the first image is an image MR1 for the right eye, and the second image is an image ML1 for the left eye. The display surface 20 includes a plurality of pixels 200 arranged along a first direction and a second direction intersecting the first direction. The pixels 200 are composed of a red subpixel, a green subpixel, and a blue subpixel.

[0013] The first direction is, for example, the X direction shown in FIG. 1. The second direction is a direction intersecting the first direction, for example, the Y direction shown in FIG. 1. The display surface 20 is parallel to the XY plane, and displays a pair of a right-eye image MR1 and a left-eye image ML1 on a plane perpendicular to the Z axis for every n (n is a positive integer greater than or equal to 2m, and m is a positive integer) pixels. Each of the right-eye image MR1 and the left-eye image ML1 is composed of m pixels in size. The right-eye image MR1 is an image viewed by the right eye ER1 of the observer P1. The left-eye image ML1 is an image viewed by the left eye EL1 of the observer P1. The pair of the right-eye image MR1 and the left-eye image ML1 is a parallax image. The right-eye image MR1 and left-eye image ML1 of the same set are correctly viewed by the right eye ER1 and left eye EL1 of the observer P1, thereby providing normal stereoscopic vision to the observer P1.

[0014] The backlight 4 is disposed on the rear surface of the display 2 and illuminates a display surface 20 of the display 2. The rear surface of the display 2 is a surface located on the opposite side of the display surface 20 from the viewer P1.

[0015] The optical element 3 is disposed in front of the display 2. The front of the display 2 is a surface located closer to the viewer P1 than the display surface 20. The optical element 3 is a parallax barrier having a light-shielding region 31 that blocks part of the display surface 20 and a light-transmitting region 32 that transmits part of the display surface 20. In this embodiment, as an example, the light-shielding region 31 and the light-transmitting region 32 are alternately arranged in the parallax barrier, thereby forming a striped pattern in which linear slits are arranged at predetermined intervals. The linear slits are inclined at a predetermined angle (tilt angle) with respect to the X-axis and Y-axis, for example. The linear slits are an example of the light-transmitting region 32.

[0016] In this embodiment, a parallax barrier having one transmissive region 32 for n pixels is used as an example of the optical element 3. The optical element 3 limits the positions of the right eye ER1 and the left eye EL1 at which the right eye image MR1 and the left eye image ML1 can be viewed, respectively. Also, as shown in FIG. 1 , in order for the right eye ER1 and the left eye EL1 of the viewer P1 to view the entire screen with normal stereoscopic vision, the viewer P1 needs to view from a position that is an optimal viewing distance OVD1 away from the optical element 3.

[0017] The camera 6 captures an image of the viewer P1. Since the viewer P1 is viewing the display 2, the viewer P1 faces the camera 6. The camera 6 includes two cameras. The image processing circuit 7 detects the positions of the viewer P1's pupils from the image of the viewer P1 captured by the camera 6 based on image processing. The image processing circuit 7 detects the positions of the viewer P1's right eye ER1 and left eye EL1 by detecting the positions of the viewer P1's pupils. The image processing circuit 7 also detects the positions of the viewer P1's pupils from the images of the viewer P1 captured by the two cameras of the camera 6. The image processing circuit 7 obtains the distance between the viewer P1 and the display surface 20 based on stereo measurement from the detected pupil positions.

[0018] Therefore, the image processing circuit 7 acquires the three-dimensional coordinates of the positions of the right eye ER1 and the left eye EL1. Information indicating the three-dimensional coordinates of the positions of the right eye ER1 and the left eye EL1 is also referred to as position information. The image processing circuit 7 outputs the acquired position information to the controller 5. Note that the image processing circuit 7 may be provided in the controller 5 or may be a device separate from the controller 5.

[0019] Based on the position information detected by the image processing circuit 7, the controller 5 calculates the area over which the right eye ER1 and the left eye EL1 observe each pixel included in the display surface 20 through the transmissive region 32. Based on the relationship between the calculated areas, the controller 5 displays the right-eye image MR1, the left-eye image ML1, and a composite image on the display surface 20. The composite image is an image obtained by combining the right-eye image MR1 and the left-eye image ML1. The right eye ER1 observes pixels assigned pixel values ​​based on the right-eye image MR1 through the transmissive region 32, and the left eye EL1 observes pixels assigned pixel values ​​based on the left-eye image ML1 through the transmissive region 32, thereby allowing the viewer P1 to perceive a stereoscopic image. The controller 5 also controls the position of the slits realized by the optical element 3. The controller 5 controls the brightness of the backlight 4.

[0020] 2 is a diagram showing an example of the functional configuration of the stereoscopic image display device 1 according to this embodiment. The stereoscopic image display device 1 includes a display unit 10, a viewpoint detection unit 11, a control unit 12, and a storage unit 13.

[0021] The display unit 10 includes a viewpoint position restriction unit 100 and an image display unit 101. The viewpoint position restriction unit 100 has the optical element 3 shown in FIG. 1. The optical element 3 restricts a first viewpoint position where a first viewpoint at which the first image and the second image are viewable is located, and a second viewpoint position where a second viewpoint is located. In one example of this embodiment, the first viewpoint is the right eye ER1 of the observer P1, and the second viewpoint is the left eye EL1 of the observer P1. The first viewpoint position is the position of the right eye ER1. The second viewpoint position is the position of the left eye EL1. The image display unit 101 has the display surface 20 shown in FIG. 1. The image display unit 101 displays the first image and the second image on the display surface 20.

[0022] The viewpoint detection unit 11 acquires the positions of the right eye ER1 and the left eye EL1 of the observer P1. The viewpoint detection unit 11 includes an imaging unit 110 and an image processing unit 111. The imaging unit 110 images the observer P1. The imaging unit 110 includes a camera 6. The image processing unit 111 acquires the three-dimensional coordinates of the positions of the right eye ER1 and the left eye EL1 based on image processing from the image captured by the imaging unit 110. The image processing unit 111 includes an image processing circuit 7.

[0023] The control unit 12 assigns an image value based on at least the first image and the second image to each pixel included on the display surface 20. The control unit 12 assigns a pixel value based on the first image to at least a portion of the pixels observed from a first viewpoint position via the optical element 3. The control unit 12 assigns a pixel value based on the second image to at least a portion of the pixels observed from a second viewpoint position via the optical element 3. The control unit 12 assigns a composite pixel value obtained by combining the pixel value based on the first image and the pixel value based on the second image at a predetermined combination ratio to at least a portion of the pixels observed from the first viewpoint position via the optical element 3 and also observed from the second viewpoint position via the optical element 3. The control unit 12 has a controller 5.

[0024] In one example of this embodiment, the control unit 12 assigns pixel values ​​based on the first image to at least a portion of pixels observed from a first viewpoint position through the transparent region 32. The control unit 12 assigns pixel values ​​based on the second image to at least a portion of pixels observed from a second viewpoint position through the transparent region 32. The control unit 12 assigns composite pixel values ​​to at least a portion of pixels observed from the first viewpoint position through the transparent region 32 and observed from the second viewpoint position through the transparent region 32. The control unit 12 also performs brightness reduction processing, which is processing for reducing the brightness of the composite pixel values.

[0025] The storage unit 13 stores various types of data. The data stored in the storage unit 13 includes, for example, image data of the right-eye image MR1 and the left-eye image ML1. The data stored in the storage unit 13 also includes data indicating a process for calculating a composite pixel value, which will be described later, and data indicating a luminance reduction process. The storage unit 13 is accessed by the control unit 12.

[0026] The control unit 12 is realized, for example, by a display control program stored in a recording medium being read and executed by a CPU (Central Processing Unit). Alternatively, the display control unit 103 may be realized by hardware including circuitry such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit). Alternatively, the control unit 12 may be realized by a combination of software and hardware. These pieces of hardware may be integrated into one unit or may be separated into multiple units.

[0027] The storage unit 13 may also be configured as a non-volatile memory such as a hard disk device, a magneto-optical disk device, or a flash memory, a read-only recording medium such as a CD-ROM, a volatile memory such as a DRAM (Dynamic Random Access Memory), or a combination of these.

[0028] It should be noted that some of the elements constituting the stereoscopic image display device 1 may be realized as devices separate from one another. When some of the elements constituting the stereoscopic image display device 1 are realized as devices separate from one another, the stereoscopic image display device 1 is also referred to as a stereoscopic image display system. For example, at least one of the controller 5, camera 6, and image processing circuit 7 included in the viewpoint detection unit 11 may be realized as a device separate from the display 2, optical element 3, and backlight 4 included in the display unit 10.

[0029] An example of a method for controlling the stereoscopic image display device 1 according to this embodiment will be described below.

[0030] The control method for the stereoscopic image display device 1 according to this embodiment has a design stage and an operation stage. The design stage is carried out when the stereoscopic image display device 1 is designed. The operation stage is carried out when the observer P1 uses the stereoscopic image display device 1.

[0031] [Design Stage] The design stage of the control method for the stereoscopic image display device 1 according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a flowchart showing an example of the procedure of the design stage of the control method for the stereoscopic image display device 1 according to this embodiment.

[0032] Step S101: Determine the number of pixels m, which is the size of each of the right-eye image MR1 and the left-eye image ML1. The sizes of the right-eye image MR1 and the left-eye image ML1 are the sizes in the X-axis direction. A method for determining this number of pixels m will now be described. On the display surface 20 of the display 2, regions (pixel regions) corresponding to n pixels, each of which is observed as being centered in the X-axis direction of the opening of the optical element 3, are present at equal intervals in the X-axis direction as viewed by an observer P1 at the optimal viewing distance OVD1. In this case, m≦n / 2 holds, and the width A of the m pixel regions in the X-axis direction is A≒E, where E is the average human eye-to-eye distance. From this relationship, the number of pixels m can be calculated by dividing the average human eye-to-eye distance E by the design width of one pixel region in the X-axis direction of the display 2. The relationship m≦n / 2 indicates that some of the n pixels may be completely invisible to the observer P1 at the optimal viewing distance OVD1. Hereinafter, the pixel area on the display surface 20 of the display 2 may be simply referred to as a pixel.

[0033] Step S102: The number of pixels (number of pixels per eye) q in the range of pixels observed by one eye (one-eye pixel range) is determined from the designed aperture ratio of the optical element 3. The aperture ratio of the parallax barrier serving as the optical element 3 is defined by the formula "(m-k) / n, k<m". k is the number of pixels out of m pixels that cannot be seen by the observer P1 at the optimum observation distance OVD1. When "k=0" and "2m=n", the "aperture ratio=50%". From the above aperture ratio, the number of pixels per eye q is "q=m-k". Note that although "k≧0" is usually true, "k<0" may also be true.

[0034] Step S103: Of the n pixels on the display surface 20 of the display 2, the number r of pixels in the range overlapping with the end surface of the parallax barrier as the optical element 3 as seen from the viewer P1 (barrier end surface overlapping pixel range) is determined.

[0035] The barrier edge surface overlapping pixel range will now be described with reference to FIG. 4 . FIG. 4 is an explanatory diagram of the barrier edge surface overlapping pixel range according to this embodiment. In the following description, the region included in the display surface 20 that is observed by the right eye ER1 via the transmissive region 32 of the optical element 3 will also be referred to as the right-eye observation region. Furthermore, the region included in the display surface 20 that is observed by the left eye EL1 via the transmissive region 32 of the optical element 3 will also be referred to as the left-eye observation region. In FIG. 4 , the right-eye observation region R1 and the right-eye observation region R2 are examples of the right-eye observation region. The left-eye observation region L1 and the left-eye observation region L2 are examples of the left-eye observation region.

[0036] 4 shows barrier edge surface B1, barrier edge surface B2, and barrier edge surface B3 as examples of barrier edge surfaces. In Fig. 4, the pixels 200 arranged on the display surface 20 are numbered from "1" to "16." Of the pixels 200, the pixels indicated by the numbers "1," "2," "9," and "10" are pixels in a barrier edge surface overlapping pixel range that overlaps with the barrier edge surface 210 of the parallax barrier serving as the optical element 3. The image displayed at the pixels in the barrier edge surface overlapping pixel range is also referred to as a mixed image.

[0037] The pixels in the barrier edge overlapping pixel range (in the example shown in FIG. 4 , the pixels indicated by the numbers "1," "2," "9," and "10") are pixels that can be seen by both the right eye ER1 and the left eye EL1 of the observer P1. Therefore, the barrier edge overlapping pixel range can be seen by both the right eye and the left eye, and can cause crosstalk. For this reason, the barrier edge overlapping pixel range is a range to which it is preferable to assign a composite pixel value, which will be described later, and to which a luminance reduction process is performed.

[0038] The number r of pixels in the barrier edge overlap pixel range can be calculated by the formula "r = a + b - 1" when the formula is "tan θ = a × Hp / (b × Vp)," where θ is the tilt angle of the parallax barrier. Here, the tilt angle θ of the parallax barrier is an angle greater than or equal to 0° and less than 90°, and when the tilt angle θ of the parallax barrier is greater than 0° (θ > 0°), in the above formula, the length of the pixel in the X direction on the display surface 20 of the display 2 is Hp, the length of the pixel in the Y direction on the display surface is Vp, and a and b are natural numbers.

[0039] Step S104: A calculation process for the composite pixel value is determined, and data indicating the determined calculation process for the composite pixel value is stored in the storage unit 13. The composite pixel value is a pixel value to be assigned to the barrier edge overlap pixel range described above. In this embodiment, the control unit 12 calculates the composite pixel value based on the formula "Pmix = SL x PL / (SL + SR) + SR x PR / (SL + SR)". Here, Pmix is ​​the composite pixel value. PL is the pixel value of a pixel in the left-eye image ML1. PR is the pixel value of a pixel in the right-eye image MR1. SL is the area of ​​a pixel observed by the left eye EL1. SR is the area of ​​a pixel observed by the right eye ER1. Note that the total pixel area is set to 1.

[0040] Therefore, when assigning a composite pixel value obtained by combining pixel values ​​based on the right-eye image MR1 and pixel values ​​based on the left-eye image ML1 at a predetermined combination ratio, the combination ratio is determined by the ratio between the area of ​​the pixel observed from the first viewpoint position and the area of ​​the pixel observed from the second viewpoint position.

[0041] However, when the composite pixel value is calculated based on the above-mentioned formula "Pmix = SL x PL / (SL + SR) + SR x PR / (SL + SR)," crosstalk occurs when the right-eye image MR1 and the left-eye image ML1 are mixed together and observed. Here, the increase in crosstalk will be described with reference to FIGS. 5 and 6.

[0042] Fig. 5 shows the state of pixels as viewed by the right eye ER1 and the left eye EL1. Here, the pixels that cause crosstalk are pixels numbered "5," "6," "13," and "14." In Fig. 5, the aperture ratio of the parallax barrier is 50%.

[0043] Fig. 6 is a calculation example of the crosstalk observed by the right eye ER1 in the pixel state shown in Fig. 5. In the example shown in Fig. 6, the pixel values ​​of the eight pixels observed through the transmission region 32 are set to 8. The total value of the pixel values ​​that do not cause crosstalk is 7.25, and the total value of the pixel values ​​that cause crosstalk is 0.75. On the other hand, when the crosstalk observed by the right eye ER1 is calculated without using composite pixels, the pixel values ​​that do not cause crosstalk are 7.5, and the pixel values ​​that cause crosstalk are 0.5.

[0044] 6, when composite pixels are not used, the pixel values ​​of the pixels numbered "5" and "14" are "0.25," and the pixel values ​​of the pixels numbered "6" and "13" are "0.75." For example, in pixel numbered "5," the area of ​​portion R51 observed by the right eye ER1 is 0.25, and the area of ​​portion R52 observed by the left eye EL1 is 0.75. In pixel numbered "13," the area of ​​portion R131 observed by the left eye EL1 is 0.25, and the area of ​​portion R132 observed by the right eye ER1 is 0.75. In pixel numbered "6," the area of ​​portion R61 observed by the right eye ER1 is 0.75, and the area of ​​portion R62 observed by the left eye EL1 is 0.25. In the pixel numbered "14," the area of ​​the portion R141 observed by the left eye EL1 is 0.75, and the area of ​​the portion R142 observed by the right eye ER1 is 0.25.

[0045] As described above, the use of composite pixels increases crosstalk. Therefore, in this embodiment, the control unit 12 applies the brightness reduction process described below to reduce the brightness value of the composite pixels.

[0046] Step S105: The luminance reduction process is determined, and data indicating the determined luminance reduction process is stored in the storage unit 13. The method for determining the luminance reduction process will be described. The control unit 12 calculates the pixel value of the composite pixel after the luminance value has been reduced based on the formula "P = Pmix × R, (0≦R≦1)." Here, P is the luminance value of the composite pixel whose luminance value has been reduced. R is a constant calculated based on the area of ​​the pixel observed by the left eye EL1 and the area of ​​the pixel observed by the right eye ER1.

[0047] More specifically, the control unit 12 calculates the pixel value of the composite pixel after the luminance value has been reduced based on, for example, the formula "P1=Pmix×|SL-SR| / (SL+SR)." Here, P1 is the luminance value of the composite pixel whose luminance value has been reduced. SL is the area of ​​the pixel observed by the left eye EL1. SR is the area of ​​the pixel observed by the right eye ER1. Here, according to the formula "P1=Pmix×|SL-SR| / (SL+SR)," the denominator "SL+SR" is the sum of the area of ​​the pixel observed by the left eye EL1 and the area of ​​the pixel observed by the right eye ER1. The larger this sum, the lower the luminance. Therefore, the luminance reduction process is a process in which the luminance reduction rate increases the larger both the area of ​​the pixel observed from the first viewpoint position and the area of ​​the pixel observed from the second viewpoint position.

[0048] As another example, the control unit 12 may calculate the pixel value of the composite pixel after the luminance value has been reduced based on the formula "P2 = Pmix × |SL - SR| / max (SL, SR)." Here, P2 is the luminance value of the composite pixel whose luminance value has been reduced. max (SL, SR) is a function that selects the larger value of SL and SR. The values ​​of P1 and P2 calculated based on the above formula are shown in FIG. 7.

[0049] [Operation Stage] The operation stage of the method for controlling the stereoscopic image display device 1 according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of the procedure of the operation stage of the method for controlling the stereoscopic image display device 1 according to this embodiment.

[0050] Step S201: The control unit 12 acquires, from the viewpoint detection unit 11, position information indicating the three-dimensional coordinates of the position of the right eye ER1 and the three-dimensional coordinates of the position of the left eye EL1.

[0051] Step S202: The image display unit 101 determines the range to which the right-eye image MR1 is to be allocated, the range to which the left-eye image ML1 is to be allocated, and the barrier end surface overlap pixel range based on the three-dimensional coordinates of the position of the right eye ER1 and the three-dimensional coordinates of the position of the left eye EL1 of the observer P1 acquired by the viewpoint detection unit 11.

[0052] Step S203: The control unit 12 causes the image display unit 101 to execute display control for the range to which the right-eye image MR1 is to be allocated, the range to which the left-eye image ML1 is to be allocated, and the barrier edge surface overlapping pixel range. Here, the control unit 12 causes the image display unit 101 to display the right-eye image MR1 in the range to which the right-eye image MR1 is to be allocated. The control unit 12 causes the image display unit 101 to display the left-eye image ML1 in the range to which the left-eye image ML1 is to be allocated.

[0053] The control unit 12 also reads data indicating a calculation process for a composite pixel value from the storage unit 13. The control unit 12 calculates a composite pixel value to be assigned to the barrier end face overlapping pixel range based on the calculation process for a composite pixel value indicated by the read data. The control unit 12 also reads data indicating a brightness reduction process from the storage unit 13. The control unit 12 calculates the pixel value of the composite pixel after the brightness value has been reduced based on the brightness reduction process indicated by the read data. The control unit 12 assigns the composite pixel value with reduced brightness to the barrier end face overlapping pixel range.

[0054] Here, a method for calculating the area of ​​pixels observed by the right eye ER1 and the left eye EL1, which are used in calculating composite pixel values ​​or brightness reduction processing, will be described. A display 2 having a display surface 20, an optical element 3 serving as a parallax barrier, and a viewpoint are arranged in a three-dimensional space. Then, of the pixels arranged on the display surface 20, the pixels whose areas are to be calculated are divided into 10 along the X-axis and 30 along the Y-axis. In other words, the pixels whose areas are to be calculated are divided into 300 regions. It is determined whether a line connecting the viewpoint and the center of each region intersects with the transmissive region of the parallax barrier. Based on the result of this determination, the number T of times the line connecting the centers of each region intersects with the transmissive region is counted. If the area of ​​a pixel arranged on the display surface 20 is 1, the area of ​​the pixel observed by the viewpoint is calculated as "T / 300."

[0055] With this, the control unit 12 ends the control method in the operation stage.

[0056] 9 shows a state in which the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap when the observer P1 moves rearward from the position shown in FIG. 4. "Rearward" refers to the direction away from the display surface 20. The movement of the right eye ER1 and left eye EL1 of the observer P1 is detected by the viewpoint detection unit 11. In the example shown in FIG. 9, the pixels 200 indicated by the numbers "8," "10," and "9" are pixels located in the area where the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap.

[0057] The state in which the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap also occurs when the observer P1 tilts his / her face, causing the position of either the right eye ER1 or the left eye EL1 to remain unchanged, while the position of the other eye moves backward.Furthermore, even if the observer P1 is in the same observation position, the state in which the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap also occurs when the observer P1 has a short inter-eye distance.

[0058] 10 shows the composite pixel values ​​assigned to the pixels indicated by the numbers "8," "10," and "9." Here, the area of ​​the pixel "9" observed by the right eye ER1 is equal to the area observed by the left eye EL1. Therefore, according to the brightness reduction process described above, the composite pixel value assigned to the pixel "9" is 0. In other words, the pixel "9" is displayed as black.

[0059] However, if the pixels observed by both the left and right eyes include black pixels, the black pixels stand out and may be observed as display unevenness. In such cases, a lower limit may be set for the luminance reduction rate. The lower limit may be set, for example, based on the condition that the luminance can be perceived. For example, since the luminance can be perceived if the pixel value is about 25%, if the lower limit for the luminance reduction rate is set to 0.25, the display unevenness becomes difficult to perceive. In other words, the luminance reduction rate may be set to "0.25≦R≦1". Here, R is the luminance reduction rate.

[0060] As another example, the luminance reduction rate may be set so that the amount of crosstalk before and after the composite pixel values ​​are assigned to pixels observed by both the left and right eyes is equal to the amount of crosstalk after the composite pixel values ​​are assigned. That is, the luminance reduction rate may be set so that "C1 = C2." Here, C1 is the amount of crosstalk before the composite pixel values ​​(Pmix) are assigned to pixels observed by both the left and right eyes. C2 is the amount of crosstalk after the composite pixel values ​​(Pmix) are assigned to pixels observed by both the left and right eyes. If the luminance reduction rate is set so that the amount of crosstalk does not change before and after the assignment of the composite pixel values, the amount of crosstalk does not substantially increase.

[0061] Fig. 11 shows a state in which the overlap between the region observed by the right eye ER1 and the region observed by the left eye EL1 becomes larger when the observer P1 moves further back than the position shown in Fig. 9. In the example shown in Fig. 11, the pixels 200 indicated by the numbers "8," "7," "10," and "9" are pixels located in the region where the region observed by the right eye ER1 and the region observed by the left eye EL1 overlap.

[0062] FIG. 12 shows composite pixel values ​​assigned to the pixels indicated by the numbers "8," "7," "10," and "9."

[0063] Fig. 13 shows a state in which the overlap between the region observed by the right eye ER1 and the region observed by the left eye EL1 becomes larger when the observer P1 moves further back than the position shown in Fig. 11. In the example shown in Fig. 13, the pixels 200 indicated by the numbers "6," "8," "7," "10," and "9" are pixels located in the region where the region observed by the right eye ER1 and the region observed by the left eye EL1 overlap. Note that pixel "8" can be viewed in its entirety by both the right eye ER1 and the left eye EL1.

[0064] 14 shows the composite pixel values ​​assigned to the pixels indicated by the numbers "6," "8," "7," "10," and "9." Here, the area of ​​pixel "8" observed by the right eye ER1 is equal to the area observed by the left eye EL1. Therefore, according to the brightness reduction process described above, the composite pixel value assigned to pixel "9" is 0. In other words, pixel "8" is displayed as black.

[0065] Therefore, the brightness reduction process is a process of assigning a pixel value that results in a substantially black display to a pixel that is observed from both the first viewpoint and the second viewpoint, among pixels that are observed from both the first viewpoint and the second viewpoint. Here, the pixel value that results in a substantially black display is a pixel value that is visually recognized by observer P1 as a black display when observed by observer P1.

[0066] 13, in order to make display unevenness less noticeable, a lower limit value of the luminance reduction rate may be set as described above. Furthermore, in order to prevent the amount of crosstalk from increasing by assigning composite pixel values, the luminance reduction rate may be set so that the amount of crosstalk before and after assigning composite pixel values ​​to pixels observed by both the left and right eyes is equal to that before and after assigning composite pixel values, as described above.

[0067] 13, the pixel "16" is a pixel that is not observed by either the left or right eye. A pixel that is not observed by either the left or right eye may be assigned, for example, the pixel value PR of the pixel in the right-eye image MR1, or the pixel value PL of the pixel in the left-eye image ML1. In another example, a pixel that is not observed by either the left or right eye may be assigned a pixel value that is a combination of the pixel value PR of the pixel in the right-eye image MR1 and the pixel value PL of the pixel in the left-eye image ML1 at a predetermined ratio.

[0068] Therefore, the control unit 12 assigns an invisible pixel value to a pixel that is not observed from the first viewpoint position and not observed from the second viewpoint position. The invisible pixel value is any one of a pixel value based on the first image, a pixel value based on the second image, a pixel value obtained by combining a pixel value based on the first image and a pixel value based on the second image at a predetermined combining ratio, a pixel value that is substantially displayed as black, and a pixel value that is substantially displayed as gray.

[0069] 15 shows a state in which the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap when the observer P1 moves forward from the position shown in FIG. 4. "Forward" refers to the direction approaching the display surface 20. The movement of the right eye ER1 and left eye EL1 of the observer P1 is detected by the viewpoint detection unit 11.

[0070] In this case, the pixel value of each pixel can be calculated in the same way as when the observer P1 moves backward (see FIGS. 9 and 10). When the observer P1 moves further forward, the pixel value of each pixel can be calculated in the same way as when the observer P1 moves further backward (see FIGS. 11 to 14).

[0071] The above explanation has been given for the cases where the observer P1 moves backward and forward, but the observer P1 can also move left and right or up and down. When the observer P1 moves left and right or up and down, the positions of the right-eye observation region and the left-eye observation region on the display surface 20 also change. When the positions of the right-eye observation region and the left-eye observation region on the display surface 20 change, the pixel value of each pixel can be calculated in the same way as when the observer P1 moves backward or forward.

[0072] Furthermore, the brightness reduction process may be a process of assigning a pixel value that results in a substantially black display when both the area of ​​the pixel observed from the first viewpoint position (i.e., the position of the right eye ER1) and the area of ​​the pixel observed from the second viewpoint position (i.e., the position of the left eye EL1) exceed a predetermined threshold. With this configuration, it is possible to suppress an increase in crosstalk with higher accuracy than a process of assigning a pixel value that results in a substantially black display to pixels that are observed from the first viewpoint position and the second viewpoint position, and that are observed entirely from the first viewpoint position (i.e., the position of the right eye ER1) and the second viewpoint position (i.e., the position of the left eye EL1).

[0073] For example, in the case of pixel number "9" in Fig. 10 described above, a process is performed in which a pixel value that results in black display is assigned when the area of ​​the pixel observed by both eyes is 0.75. In contrast, by setting an appropriate threshold value (e.g., 0.5) for each of the areas of the pixel observed by both eyes, the increase in crosstalk for pixel number "9" can be suppressed with higher accuracy.

[0074] In the following, a modified example of the brightness reduction process will be described for a case where the observer P1 moves left and right, in which a pixel value that essentially results in a black display is assigned when both the area of ​​the pixel observed from the position of the right eye ER1 and the area of ​​the pixel observed from the position of the left eye EL1 exceed a predetermined threshold. Note that this modified brightness reduction process may also be applied to a case where the observer P1 moves in at least one of the left and right directions or the front and rear directions.

[0075] 16 shows a state in which there is minimal overlap between the area observed by the right eye ER1 and the area observed by the left eye EL1. In the example shown in FIG. 16, the pixels 200 indicated by the numbers "5," "6," "13," and "14" are pixels located in the area where the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap. The value of the number of pixels per eye q is 8.

[0076] In the state shown in Figure 16, in pixel number "5", the area of ​​the portion observed by the right eye ER1 (portion causing crosstalk) is 0.25, and the area of ​​the portion observed by the left eye EL1 is 0.75. In pixel number "6", the area of ​​the portion observed by the right eye ER1 is 0.75, and the area of ​​the portion observed by the left eye EL1 (portion causing crosstalk) is 0.25. In pixel number "13", the area of ​​the portion observed by the left eye EL1 (portion causing crosstalk) is 0.25, and the area of ​​the portion observed by the right eye ER1 is 0.75. In pixel number "14", the area of ​​the portion observed by the left eye EL1 is 0.75, and the area of ​​the portion observed by the right eye ER1 (portion causing crosstalk) is 0.25.

[0077] Fig. 17 shows a state in which the maximum overlap occurs between the area observed by the right eye ER1 and the area observed by the left eye EL1 when the observer P1 moves leftward (toward the left, i.e., toward the positive side in the X-axis direction) from the position shown in Fig. 16. In the example shown in Fig. 17, the pixels 200 indicated by the numbers "5," "6," "7," "13," "14," and "15" are pixels located in the area where the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap.

[0078] In the state shown in FIG. 17 , for pixel number "6," the area of ​​the portion observed by the right eye ER1 is 0.5, and the area of ​​the portion observed by the left eye EL1 (the portion causing crosstalk) is 0.5. For pixel number "14," the area of ​​the portion observed by the right eye ER1 (the portion causing crosstalk) is 0.5, and the area of ​​the portion observed by the left eye EL1 is 0.5. In other words, the areas of the crosstalk portions for pixel number "6" and pixel number "14" are equal. Even if the right-eye image MR1 and the left-eye image ML1 are swapped for pixel number "6" and pixel number "14," no change occurs in the luminance difference. Therefore, it is possible to move each of the right-eye image MR1 and the left-eye image ML1 horizontally by one pixel (to the right in the illustrated example). This process enables horizontal eye tracking.

[0079] The threshold value for the brightness reduction process described above must be set to a value that ensures the operation of this horizontal eye tracking. This value is 0.5. Therefore, when the area of ​​a pixel observed from the position of the right eye ER1 and the area of ​​a pixel observed from the position of the left eye EL1 both exceed 0.5, the eye tracking operation is guaranteed by the brightness reduction process that assigns a pixel value that essentially results in a black display.

[0080] 18 shows a state in which the left-eye image ML1 has shifted by one pixel in the left-right direction (to the left, i.e., toward the positive X-axis direction) from the position shown in FIG. 17 , resulting in minimal overlap between the area observed by the right eye ER1 and the area observed by the left eye EL1. As described above, the threshold value for the brightness reduction process is set to 0.5. In the example shown in FIG. 18 , the pixels 200 indicated by the numbers "5," "6," "7," "13," "14," and "15" are pixels located in the area where the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap.

[0081] 18, in pixel number "6," the area of ​​the portion observed by the right eye ER1 is 0.75, and the area of ​​the portion observed by the left eye EL1 (the portion causing crosstalk) is 0.75. Since both the area of ​​the pixel observed by the right eye ER1 and the area of ​​the pixel observed by the left eye EL1 for pixel number "6" exceed the predetermined threshold of 0.5, a pixel value that displays black is assigned.

[0082] On the other hand, for pixel number "14," the area of ​​the pixel observed by the right eye ER1 is compared with the area of ​​the pixel observed by the left eye EL1, and the image corresponding to the eye with the larger area, either the right-eye image MR1 or the left-eye image ML1, is displayed. In other words, for pixel number "14," if the area of ​​the pixel observed by the right eye ER1 is larger than the area of ​​the pixel observed by the left eye EL1, the right-eye image MR1 is displayed, and if the area of ​​the pixel observed by the left eye EL1 is larger than the area of ​​the pixel observed by the right eye ER1, the left-eye image ML1 is displayed.

[0083] Fig. 19 shows a state in which the maximum overlap occurs between the area observed by the right eye ER1 and the area observed by the left eye EL1 when the observer P1 moves leftward (toward the left, i.e., toward the positive side in the X-axis direction) from the position shown in Fig. 18. In the example shown in Fig. 19, the pixels 200 indicated by the numbers "5," "6," "7," "8," "13," "14," "15," and "0" are pixels located in the area where the area observed by the right eye ER1 and the area observed by the left eye EL1 overlap.

[0084] 17, the pixel numbered "6" was assigned a pixel value that resulted in a black display, but in the state shown in FIG. 18, if the area of ​​the portion observed by the right eye ER1 is 0.5 or less, the pixel numbered "6" displays the left-eye image ML1. In the state shown in FIG. 17, the pixel numbered "7" displayed the right-eye image MR1, but in the state shown in FIG. 18, if the area of ​​the portion observed by the left eye EL1 is greater than 0.5, the pixel numbered "14" is assigned a pixel value that results in a black display, because the area of ​​the portion observed by the right eye ER1 is larger than the area of ​​the portion observed by the left eye EL1 compared to the state shown in FIG. 17, so the pixel numbered "14" displays the right-eye image MR1. This concludes the description of the brightness reduction process of the modified example.

[0085] 1 , the optical element 3, which is a parallax barrier, has a finite thickness. The light-shielding region 31 and the light-transmitting region 32 are formed on a transparent substrate such as glass or resin. The light-shielding region 31 and the light-transmitting region 32 may be formed on the display surface 20 side of the substrate, or on the viewer P1 side of the substrate.

[0086] Regardless of whether the shading region 31 and the transparent region 32 are formed on either side of the substrate, it is preferable that the control unit 12 take into account the refraction of light in the substrate on which the shading region 31 and the transparent region 32 are formed when calculating the area over which the right eye ER1 and the left eye EL1 observe each pixel through the transparent region 32 based on the position information of the right eye ER1 and the left eye EL1 detected by the viewpoint detection unit 11.

[0087] Therefore, the control unit 12 may perform a correction based on the refractive index for the area of ​​a pixel observed from the position of the right eye ER1 and the area of ​​a pixel observed from the position of the left eye EL1. Due to the refraction of light at the substrate, pixels located away from the front of the viewpoint in a direction parallel to the display surface 20 (the X-axis direction or the Y-axis direction) are observed to be closer to the viewer P1 than pixels on the display surface 20 located directly in front of the viewpoint. By taking into account the phenomenon in which the position of a pixel relative to the viewer P1 is perceived differently from its actual position by the viewer P1 due to this refraction of light, the area observed by the right eye ER1 and the left eye EL1 can be calculated more accurately.

[0088] Second Embodiment [When the aperture ratio is less than 50%] In this embodiment, a case where the design aperture ratio of the parallax barrier as the optical element 3 is less than 50% will be described. In this embodiment, a case where the aperture ratio is 25% will be described. Note that the configuration of the stereoscopic image display device is the same as the configuration of the stereoscopic image display device 1 according to the first embodiment.

[0089] 20 shows a state in which right-eye observation regions and left-eye observation regions are evenly aligned on the display surface 20. In other words, the distance between adjacent right-eye observation regions and left-eye observation regions is equal. In FIG. 20, right-eye observation region R21 and right-eye observation region R22 are examples of right-eye observation regions. Left-eye observation region L21 and left-eye observation region L22 are examples of left-eye observation regions.

[0090] On the other hand, Figure 21 shows a state in which observer P1 has moved further back than the position shown in Figure 20, resulting in an overlap between the right-eye observation region and the left-eye observation region. "Backward" refers to the direction away from the display means. Of the pixels 200, the pixels indicated by the numbers "6," "8," and "7" are pixels included in the overlapping region between the right-eye observation region and the left-eye observation region.

[0091] Even when the aperture ratio is smaller than 50%, the pixel value of each pixel is calculated in the same manner as in Example 1. Even when the observer P1 moves left and right or up and down, the pixel value of each pixel is calculated in the same manner as in Example 1.

[0092] Third Embodiment [When the display boundary between the right-eye image MR1 and the left-eye image ML1 is determined based on the viewpoint position] In this embodiment, a case will be described in which the display boundary between the right-eye image MR1 and the left-eye image ML1 is determined based on the viewpoint position detected by the viewpoint detection unit, and the right-eye image MR1 is displayed on one side of the display boundary, and the left-eye image ML1 is displayed on the other side. In this embodiment, regardless of the position of the observer P1, there is no overlap between the right-eye image MR1 and the left-eye image ML1, and no invisible pixels. Because the right-eye image MR1 and the left-eye image ML1 do not overlap, only pixels on the display boundary line are pixels where the mixed image is displayed. Note that the configuration of the stereoscopic video display device is the same as the configuration of the stereoscopic video display device 1 according to the first embodiment, except that the control unit 12 performs processing to determine the display boundary between the right-eye image and the left-eye image.

[0093] [Operation Stage] The operation stage of the control method for the stereoscopic image display device 1 according to this embodiment will be described with reference to Fig. 22. Fig. 22 is a flowchart showing an example of the procedure of the operation stage of the control method for the stereoscopic image display device 1 according to this embodiment. Note that the processes of steps S301, S303, and S304 are similar to the processes of steps S201, S202, and S203 in Fig. 8, and therefore will not be described again.

[0094] Step S302: The control unit 12 determines the positions of the display areas for the right-eye image MR1 and the left-eye image ML1 and their boundary lines based on the position information detected by the viewpoint detection unit 11. The control unit 12 determines the positions of the display areas for the right-eye image MR1 and the left-eye image ML1 and their boundary lines, for example, by calculating a line where the center positions of the positions of the right eye ER1 and the left eye EL1 and the plane represented by the center lines of each transparent region of the parallax barrier intersect with the display surface 20. In this embodiment, the right-eye observation region and the left-eye observation region do not overlap. Therefore, regardless of the front-back, left-right, or top-bottom position of the viewer P1, the edges of the display areas for the right-eye image MR1 and the left-eye image ML1 coincide with each other.

[0095] Therefore, the viewpoint detection unit 11 detects the position of the right eye ER1 in accordance with the movement of the right eye ER1, and detects the position of the left eye EL1 in accordance with the movement of the left eye EL1. The control unit 12 updates the pixels to which pixel values ​​based on the right-eye image MR1 are assigned, based on the position of the right eye ER1 detected by the viewpoint detection unit 11. The control unit 12 updates the pixels to which pixel values ​​based on the left-eye image ML1 are assigned, based on the position of the left eye EL1 detected by the viewpoint detection unit 11. The control unit 12 also updates the pixels to which composite pixel values ​​are assigned, based on the positions of the right eye ER1 and the left eye EL1 detected by the viewpoint detection unit 11. With this, the control unit 12 ends the control method for the operation stage.

[0096] 23 shows an example of the display surface 20 when the display boundary between the right-eye image MR1 and the left-eye image ML1 is determined based on the position of the viewpoint. The control unit 12 calculates the area belonging to the display area of ​​the right-eye image MR1 and the area belonging to the display area of ​​the left-eye image ML1 for pixels located on the boundary line between the display area of ​​the right-eye image MR1 and the display area of ​​the left-eye image ML1. The control unit 12 determines the pixel value of the pixel located on the boundary line based on the ratio of the area belonging to the display area of ​​the right-eye image MR1 to the area belonging to the display area of ​​the left-eye image ML1.

[0097] 23, pixels 200 indicated by the numbers "2," "1," "10," and "9" are pixels that exist on the boundary line between the display area of ​​the right-eye image MR1 and the display area of ​​the left-eye image ML1. The composite pixel values ​​assigned to the pixels indicated by the numbers "2," "1," "10," and "9" are shown in FIG.

[0098] The configuration of the image display unit 101 is not limited to the configurations shown in the above-described embodiments. For example, in the above-described embodiments, an example has been described in which pixels on the display surface 20 are composed of red subpixels, green subpixels, and blue subpixels, and the pixels are arranged in a horizontal and vertical grid pattern. However, the present invention is not limited to this. On the display surface 20, the pixels may be arranged based on a so-called delta arrangement in which the pixels are arranged with a half-pitch offset between rows, or an arrangement called a honeycomb structure. Furthermore, the red subpixels, green subpixels, and blue subpixels may be arranged in diagonal stripes instead of vertical stripes.

[0099] Furthermore, like a rear projection display using one-chip DLP (Digital Light Processing) (registered trademark), the image display unit 101 may have square pixels arranged on the display surface 20, and may display red subpixels, green subpixels, and blue subpixels in a time-division manner. Also, like an LED (light-emitting diode) display, one pixel in the image display unit 101 may be configured by LED elements of three colors, RGB.

[0100] Furthermore, in each of the above-described embodiments, an example has been described in which the light-shielding regions and the transmissive regions are formed at an angle in the optical element 3, which is a parallax barrier, but this is not limiting. In the parallax barrier, the light-shielding regions and the transmissive regions may be formed in a vertical stripe pattern, or the light-shielding regions and the transmissive regions may both be formed in a rectangular grid pattern. Furthermore, in the parallax barrier, multiple transmissive regions may be formed within a continuous light-shielding region, or multiple light-shielding regions may be formed within a continuous transmissive region. Therefore, as long as the right eye ER1 and the left eye EL1 are configured to be able to observe different regions, there are no restrictions on the arrangement of the light-shielding regions and the transmissive regions in the parallax barrier.

[0101] In addition, in each of the above-described embodiments, an example in which the optical element 3 is disposed in front of the display surface 20 (i.e., on the side of the viewer P1) has been described, but the present invention is not limited to this. The image display unit 101 may be configured with a transmissive liquid crystal display and a backlight, and the optical element 3 may be disposed between the liquid crystal display and the backlight.

[0102] Furthermore, in the above-described embodiments, the cases where the aperture ratio of the parallax barrier is 50% and where it is less than 50% (25%) are shown, but even when the aperture ratio is greater than 50%, the pixel value of each pixel can be calculated in the same way as in the above-described embodiments.

[0103] Furthermore, in the above-described embodiments, an example has been described in which the composite pixel value is calculated based on the formula "Pmix = SL x PL / (SL + SR) + SR x PR / (SL + SR)." However, this is not limiting. The composite ratio may be determined based on the relationship between the area of ​​a pixel observed from a first viewpoint position and the area of ​​a pixel observed from a second viewpoint position. For example, when SL > 0 and SR = 0, the composite pixel value may be calculated based on the formula "Pmix = PL." When SL = 0 and SR > 0, the composite pixel value may be calculated based on the formula "Pmix = PR." When 0 < SR < SL, the composite pixel value may be calculated based on the formula "Pmix = 0.75 PL + 0.25 PR." When 0 < SL < SR, the composite pixel value may be calculated based on the formula "Pmix = 0.25 PL + 0.75 PR." When 0 < SL < SR, the composite pixel value may be calculated based on the formula "Pmix = 0.5 PL + 0.5 PR."

[0104] In the above-described embodiments, an example has been described in which the brightness reduction process is performed based on a formula based on the difference between the area of ​​a pixel observed from a first viewpoint position and the area of ​​a pixel observed from a second viewpoint position, but this is not limiting. In the brightness reduction process, the brightness may be reduced based on the sum of the area of ​​a pixel observed from the first viewpoint position and the area of ​​a pixel observed from the second viewpoint position. For example, the larger the sum of the areas, the smaller the pixel value. Therefore, the brightness reduction process may be based on any method as long as it can reduce the brightness.

[0105] In addition, in the above-described embodiments, an example has been described in which a pixel value based only on the first image is assigned to a pixel observed only from the first viewpoint position, a pixel value based only on the second image is assigned to a pixel observed only from the second viewpoint position, and a composite pixel value obtained by combining pixels observed from the first viewpoint position and the second viewpoint position at a predetermined combining ratio determined by the relationship between the area of ​​the pixel observed from the first viewpoint position and the area of ​​the pixel observed from the second viewpoint position is assigned to a pixel observed from the first viewpoint position. In other words, in the above-described embodiments, an example has been described in which a pixel on which a mixed image is displayed is distinguished from a pixel on which a first image is displayed and a pixel on which a second image is displayed, and a composite pixel value is assigned to the pixel on which the mixed image is displayed. However, this is not limited to this. As described below, a pixel value may be assigned to each pixel based on the ratio between the area of ​​the pixel observed from the first viewpoint position and the area of ​​the pixel observed from the second viewpoint position, without distinguishing between the pixel on which a mixed image is displayed and the pixel on which a first image is displayed and the pixel on which a second image is displayed.

[0106] In this case, for example, the control unit 12 assigns to each pixel 200 a composite pixel value obtained by combining a pixel value based on the first image and a pixel value based on the second image, based on the ratio between the area of ​​the pixel observed from the first viewpoint and the area of ​​the pixel observed from the second viewpoint. As a result of this processing for all pixels 200, the control unit 12 assigns pixel values ​​based only on the first image to pixels observed only from the first viewpoint, assigns pixel values ​​based only on the second image to pixels observed only from the second viewpoint, and assigns composite pixel values ​​obtained by combining pixel values ​​based on the first image and pixel values ​​based on the second image that are greater than zero to pixels observed from both the first and second viewpoints. In this processing, the control unit 12 does not need to determine the pixels at which the combined image is displayed. In other words, the control unit 12 does not need to determine the display boundary between the first and second images.

[0107] Furthermore, in the above-described embodiments, an example of a case where it is predetermined to perform the brightness reduction process has been described. However, this is not limiting. The control unit 12 may determine whether to perform the brightness reduction process for each frame in which images (right-eye image MR1 and left-eye image ML1) are displayed. In this case, for example, the control unit 12 performs the brightness reduction process for each frame when crosstalk is greater than or equal to a predetermined level. The control unit 12 may also determine whether to perform the brightness reduction process for each pixel. In this case, for example, the control unit 12 performs the brightness reduction process for a pixel when the brightness value of the pixel is greater than or equal to a predetermined level. The control unit 12 may also determine whether to perform the brightness reduction process based on the sum of the brightness values ​​for all pixels 200. In this case, for example, the control unit 12 performs the brightness reduction process for all pixels 200 when the sum of the brightness values ​​for all pixels 200 is greater than or equal to a predetermined level. The control unit 12 may not perform the brightness reduction process regardless of the conditions.

[0108] Furthermore, in each of the above-described embodiments, an example has been described in which position information indicating the three-dimensional coordinates of the positions of the right eye ER1 and the left eye EL1 is acquired by capturing an image of the observer P1 with the camera 6 and detecting pupil positions through image processing, but this is not limiting. The center of the head of the observer P1 may be detected, and the positions of the left and right eyes may be estimated and acquired from the general distance between the left and right eyes. Therefore, the method of acquiring the position information, that is, the tracking method, may be any method.

[0109] In addition, in each of the above-described embodiments, an example has been described in which the distance between the right eye ER1 and the left eye EL1 is obtained by detecting the pupils using two cameras, but this is not limiting. The distance between the right eye ER1 and the left eye EL1 may also be obtained based on a method known as time of flight, which calculates the distance from the time it takes for infrared light to be emitted and reflected at the pupil position and return. Therefore, any method may be used to obtain the distance between the right eye ER1 and the left eye EL1.

[0110] In addition, in each of the above-described embodiments, an example of a display device that provides a right-eye image MR1 and a left-eye image ML1 to the left and right eyes to allow the viewer to view a stereoscopic image has been described, but the present invention is not limited to this. The display device may simultaneously provide different images to two observers P1. In this case, the positions of the two observers P1 may be detected by, for example, a camera. The distance between the two observers P1 may be obtained by stereo measurement using two cameras, or may be obtained by a time-of-flight method.

[0111] Furthermore, in the above-described embodiments, an example of a method for calculating the area of ​​a pixel observed by the right eye ER1 and the left eye EL1 has been described in which the number of times a straight line connecting the viewpoint and the center of each region obtained by dividing the pixel in three-dimensional space intersects with the transparent region of the parallax barrier has been counted, but the method is not limited to this. For example, if the shortest horizontal distance on the parallax barrier surface between the straight line connecting the viewpoint and the center of the pixel and the edge of the transparent region of the parallax barrier is distance L, the area S of the pixel observed from the viewpoint can be expressed as a function with distance L as a variable. Therefore, the distance L can be calculated for each pixel to calculate the area S. In this case, a table showing the relationship between distance L and area S can be stored in advance in storage unit 13, and the area S can be calculated by referring to this table.

[0112] Furthermore, in the above-described embodiments, for ease of explanation, an example has been described in which the inclination of the transmissive regions (slits) and light-blocking regions of the parallax barrier is such that one pixel advances horizontally and two pixels advance downward, but this is not limiting. Therefore, the inclination of the transmissive regions (slits) and light-blocking regions is not limited to this and may be any angle. In particular, the transmissive regions (slits) and light-blocking regions do not have to be inclined at a predetermined angle with respect to the X-axis and Y-axis.

[0113] Furthermore, in each of the above-described embodiments, for ease of explanation, pixels are numbered from "1" to "16." However, in reality, it is not necessary to number pixels; pixel values ​​can be determined from the relationship between the viewpoint position and the transmissive and opaque areas of the parallax barrier.

[0114] Furthermore, in the above-described embodiments, an example has been described in which a pixel that is not observed by both the left and right eyes is assigned the pixel value PR of the pixel in the right-eye image MR1, the pixel value PL of the pixel in the left-eye image ML1, or a pixel value obtained by combining the pixel value PR of the pixel in the right-eye image MR1 and the pixel value PL of the pixel in the left-eye image ML1 at a predetermined ratio, but this is not limiting. A pixel that is not observed by both the left and right eyes may be assigned, for example, the average value of the pixel values ​​of the pixels adjacent to that pixel, or the average value of the pixel values ​​of the eight pixels surrounding that pixel.

[0115] Alternatively, pixels that are not viewed by both the left and right eyes may be assigned pixel values ​​that result in a black display. Since assigning pixel values ​​that result in a black display may result in display unevenness, pixels that are not viewed by both the left and right eyes may be assigned pixel values ​​that result in a gray display. When assigning pixel values ​​that result in a black display or a gray display to pixels that are not viewed by both the left and right eyes, the pixel values ​​may be any of the following: a pixel value obtained by converting the pixel value PR of a pixel in the image MR1 for the right eye into a luminance value; a pixel value obtained by converting the pixel value PL of a pixel in the image ML1 for the left eye into a luminance value; and a pixel value obtained by combining the pixel value PR of a pixel in the image MR1 for the right eye and the pixel value PL of a pixel in the image ML1 for the left eye at a predetermined ratio and converting it into a luminance value. By displaying pixels that are not viewed by both the left and right eyes in black or gray, it is possible to reduce crosstalk that occurs when light generated from a pixel is multiple-reflected between the display surface and the substrate of the parallax barrier and reaches the left and right eyes of the viewer P1.

[0116] Furthermore, in each of the above-described embodiments, an example has been described in which a parallax barrier is used as an optical element that changes the observed area on the display surface 20 of the image display unit 101 depending on the viewpoint position, but this is not limiting. The optical element that changes the observed area on the display surface 20 of the image display unit 101 depending on the viewpoint position may be a lenticular lens or a microlens array that changes the observed area due to the effect of the lens. Any configuration may be used as long as the observed area changes depending on the viewpoint position.

[0117] The following describes a method for calculating the area of ​​pixels observed by the right eye ER1 and the left eye EL1 when a lenticular lens is used. The display 2, lenticular lens, and viewpoint are arranged in three-dimensional space. The lenticular lens surface is then divided into N sections horizontally and M sections vertically, and light rays are emitted from the viewpoint toward each point. Here, N is an integer greater than the horizontal resolution of the display 2. M is an integer greater than the vertical resolution of the display means. Each light ray is traced taking into account the refractive index of the lenticular lens, and the pixels it intersects with on the display surface 20 of the display 2 are counted. Counting is performed for various viewpoint positions, and the area of ​​the pixel with the maximum count is set to 1. The areas of the other pixels are determined by the relative values ​​of the counts relative to the maximum count.

[0118] Since lenses have focusing properties, it is preferable to calculate an area that takes into account the refraction of light, or in other words, a weighted area, as described in the first embodiment, rather than calculating the actual area of ​​the pixels observed by the right eye ER1 and the left eye EL1.

[0119] As described above, the image display device according to each embodiment (in the present embodiment, the three-dimensional image display device 1) includes a viewpoint position restriction unit 100, an image display unit 101, and a control unit 12. The viewpoint position restriction unit 100 includes an optical element 3 that restricts a first viewpoint position (in each embodiment, the position of the right eye ER1) at which a first viewpoint (in each embodiment, the right eye ER1) is located, and a second viewpoint position (in each embodiment, the position of the left eye EL1) at which a second viewpoint (in each embodiment, the left eye EL1) is located, at which a first image (in each embodiment, the image for the right eye MR1) and a second image (in each embodiment, the image for the left eye ML1) are visible, respectively. The image display unit 101 includes a display surface 20 including a plurality of pixels (in each embodiment, the pixel 200), and displays the first image (in each embodiment, the image for the right eye MR1) and the second image (in each embodiment, the image for the left eye ML1) on the display surface 20. The control unit 12 assigns image values ​​based on at least a first image (in each embodiment, a right-eye image MR1) and a second image (in each embodiment, a left-eye image ML1) to each pixel (in each embodiment, a pixel 200) included in the display surface 20. The control unit 12 assigns pixel values ​​based on the first image (in each embodiment, a right-eye image MR1) to at least a portion of the pixels observed from a first viewpoint position (in each embodiment, the position of the right eye ER1) through an optical element (in each embodiment, the transmissive region 32 of the optical element 3), and assigns pixel values ​​based on the second image (in each embodiment, the left-eye image ML1) to at least a portion of the pixels observed from a second viewpoint position (in each embodiment, the position of the left eye EL1) through an optical element (in each embodiment, the transmissive region 32 of the optical element 3). At least a portion of the pixels observed from a first viewpoint position (the position of the right eye ER1 in each embodiment) through the optical element (the transparent region 32 of the optical element 3 in each embodiment) and observed from a second viewpoint position (the position of the left eye EL1 in each embodiment) through the optical element (the transparent region 32 of the optical element 3 in each embodiment) are assigned a composite pixel value obtained by combining pixel values ​​based on the first image (the image for the right eye MR1 in each embodiment) and pixel values ​​based on the second image (the image for the left eye ML1 in each embodiment) at a predetermined combination ratio.

[0120] With this configuration, in the image display device according to this embodiment (in this embodiment, the stereoscopic image display device 1), composite pixel values ​​are assigned to at least a portion of the pixels observed from the first viewpoint position (in each embodiment, the position of the right eye ER1) through the optical element (in each embodiment, the transmissive region 32 of the optical element 3) and observed from the second viewpoint position (in each embodiment, the position of the left eye EL1) through the optical element (in each embodiment, the transmissive region 32 of the optical element 3). This allows display without creating reversed viewing areas across the entire display surface 20, regardless of the observer's position. Furthermore, in the image display device according to this embodiment (in this embodiment, the stereoscopic image display device 1), the first image and the second image on the display surface 20 are observed to gradually switch, so no discomfort is felt. When the two images are an image for the right eye and an image for the left eye, as in this embodiment, a stereoscopic image can be observed across the entire display surface 20 without any discomfort.

[0121] Furthermore, the allocation of composite pixel values ​​may result in an increase in crosstalk compared to before the allocation of composite pixel values. In the image display device according to this embodiment (in this embodiment, the three-dimensional image display device 1), the increase in crosstalk can be suppressed by lowering the luminance of the composite pixel values ​​through luminance reduction processing.

[0122] Conventionally, in naked-eye stereoscopic viewing, there exists an inverted viewing area where a stereoscopic image cannot be observed. Inverted viewing occurs when an image for the left eye is observed by the right eye, and an image for the right eye is observed by the left eye. Because of the inverted viewing area, if the viewer moves left or right more than the number of viewpoints and enters the inverted viewing area, the stereoscopic image cannot be observed. Furthermore, if the viewer moves forward or backward more than a predetermined distance, an inverted viewing area occurs within the screen, and a portion of the stereoscopic image on the screen cannot be observed. Furthermore, as the number of viewpoints increases, the resolution per viewpoint decreases, and the image quality deteriorates. As described above, the image display device according to this embodiment (in this embodiment, the stereoscopic image display device 1) can display images across the entire display surface 20 without creating an inverted viewing area, regardless of the viewer's position.

[0123] Note that a part of the image display device (3D image display device 1) in each of the above-described embodiments, for example, the control unit 12, may be implemented by a computer. In this case, a program for implementing this control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. Note that the "computer system" here refers to a computer system built into the 3D image display device 1, and includes hardware such as an operating system (OS) and peripheral devices. Furthermore, the "computer-readable recording medium" refers to portable media such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a CD-ROM (Compact Disc-Read Only Memory), and a storage device such as a hard disk built into a computer system. Furthermore, the term "computer-readable recording medium" may include a medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a medium that stores a program for a fixed period of time, such as a volatile memory within a computer system that serves as a server or client in such a case. The program may be for implementing part of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system. Furthermore, part or all of the control unit 12 in the above-described embodiment may be implemented as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the control unit 12 may be implemented as a processor individually, or part or all of the blocks may be integrated into a processor. The integrated circuit implementation method is not limited to LSI, and may also be implemented using a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that replaces LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

[0124] One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention.

[0125] 1...3D image display device, 2...display, 20...display surface, 200...pixel, 3...optical element, light-shielding area 31..., 32...transmitting area, 5...controller, 100...viewpoint position restriction unit, 101...image display unit, 12...control unit, MR1...image for right eye, ML1...image for left eye, ER1...right eye, EL1...left eye

Claims

1. An image display device comprising: a viewpoint position restriction unit having an optical element which restricts a first viewpoint position where a first viewpoint is located and a second viewpoint position where a second viewpoint is located, at which a first image and a second image can be viewed, respectively; an image display unit having a display surface including a plurality of pixels and displaying the first image and the second image on the display surface; and a control unit which assigns image values ​​based on at least the first image and the second image to each pixel included on the display surface, wherein the control unit: assigns pixel values ​​based on the first image to at least a portion of pixels observed from the first viewpoint position through the optical element; assigns pixel values ​​based on the second image to at least a portion of pixels observed from the second viewpoint position through the optical element; and assigns a composite pixel value obtained by combining the pixel value based on the first image and the pixel value based on the second image at a predetermined combination ratio, to at least a portion of pixels observed from the first viewpoint position through the optical element and observed from the second viewpoint position through the optical element.

2. The image display device of claim 1, wherein the optical element is a parallax barrier having a light-shielding region that blocks part of the display surface and a transparent region that transmits part of the display surface, and the control unit: assigns pixel values ​​based on the first image to at least a portion of pixels observed from the first viewpoint position through the transparent region; assigns pixel values ​​based on the second image to at least a portion of pixels observed from the second viewpoint position through the transparent region; and assigns the composite pixel value to at least a portion of pixels observed from the first viewpoint position through the transparent region and observed from the second viewpoint position through the transparent region.

3. The image display device of claim 2, wherein the first viewpoint is the right eye of an observer, the second viewpoint is the left eye of the observer, the first image is an image for the right eye, the second image is an image for the left eye, and the observer perceives a stereoscopic image by the right eye observing pixels assigned with pixel values ​​based on the image for the right eye through the transparent region and the left eye observing pixels assigned with pixel values ​​based on the image for the left eye through the transparent region.

4. The image display device according to claim 1, wherein the blending ratio is determined by a relationship between an area of ​​a pixel observed from the first viewpoint position and an area of ​​a pixel observed from the second viewpoint position.

5. The image display device according to claim 1, wherein the blending ratio is determined by a ratio between an area of ​​a pixel observed from the first viewpoint position and an area of ​​a pixel observed from the second viewpoint position.

6. The image display device according to claim 1, wherein the control unit further performs a luminance reduction process for reducing the luminance of the composite pixel value.

7. The image display device according to claim 6, wherein the brightness reduction process is a process in which the rate of brightness reduction is increased as both the area of ​​the pixel observed from the first viewpoint position and the area of ​​the pixel observed from the second viewpoint position are larger.

8. The image display device according to claim 6, wherein the brightness reduction process is a process of assigning a pixel value that essentially results in a black display when both the area of ​​a pixel observed from the first viewpoint position and the area of ​​a pixel observed from the second viewpoint position exceed predetermined thresholds.

9. The image display device according to claim 6, wherein the brightness reduction process is a process of assigning a pixel value that is essentially displayed as black to pixels that are observed from the first viewpoint position and from the second viewpoint position, and that are observed entirely from the first viewpoint position and from the second viewpoint position.

10. The image display device of claim 1, further comprising a viewpoint detection unit that detects the first viewpoint position in response to movement of the first viewpoint and detects the second viewpoint position in response to movement of the second viewpoint, wherein the control unit: updates pixels to which pixel values ​​based on the first image are assigned based on the detected first viewpoint position; updates pixels to which pixel values ​​based on the second image are assigned based on the detected second viewpoint position; and updates pixels to which the composite pixel value is assigned based on the detected first viewpoint position and second viewpoint position.

11. The image display device according to claim 1, wherein the control unit further assigns an invisible pixel value to pixels that are not observed from the first viewpoint position and are not observed from the second viewpoint position.

12. The image display device according to claim 11, wherein the invisible pixel value is any one of a pixel value based on the first image, a pixel value based on the second image, a pixel value obtained by combining a pixel value based on the first image and a pixel value based on the second image at a predetermined combining ratio, a pixel value that essentially results in a black display, and a pixel value that results in a gray display.

13. The image display device of claim 1, wherein the control unit assigns to all of the pixels, for each pixel, a composite pixel value obtained by combining a pixel value based on the first image and a pixel value based on the second image based on a ratio between the area of ​​the pixel observed from the first viewpoint position and the area of ​​the pixel observed from the second viewpoint position, thereby assigning pixel values ​​based only on the first image to pixels observed only from the first viewpoint position, assigning pixel values ​​based only on the second image to pixels observed only from the second viewpoint position, and assigning composite pixel values ​​obtained by combining a pixel value based on the first image and a pixel value based on the second image to pixels observed from the first viewpoint position and also observed from the second viewpoint position.

14. The image display device according to claim 4, wherein the control unit performs a correction based on a refractive index for the area of ​​a pixel observed from the first viewpoint position and the area of ​​a pixel observed from the second viewpoint position.

15. A video display control device provided as the control unit in a video display device comprising: a viewpoint position limiting unit having an optical element that limits a first viewpoint position at which a first viewpoint is located and a second viewpoint position at which a second viewpoint is located, at which each of a first image and a second image is viewable; an image display unit having a display surface including a plurality of pixels and displaying the first image and the second image on the display surface; and a control unit that assigns image values ​​based on at least the first image and the second image to each pixel included in the display surface, wherein the video display control device assigns pixel values ​​based on the first image to at least a portion of pixels observed from the first viewpoint position through the optical element, assigns pixel values ​​based on the second image to at least a portion of pixels observed from the second viewpoint position through the optical element, and assigns a composite pixel value obtained by combining the pixel value based on the first image and the pixel value based on the second image at a predetermined composite ratio to at least a portion of pixels observed from the first viewpoint position through the optical element and from the second viewpoint position through the optical element.

16. A program for causing a computer as a control unit provided in an image display device comprising: a viewpoint position limiting unit having an optical element that limits a first viewpoint position at which a first viewpoint is located and a second viewpoint position at which a second viewpoint is located, at which each of a first image and a second image is visible; an image display unit having a display surface including a plurality of pixels and displaying the first image and the second image on the display surface; and a control unit that assigns image values ​​based on at least the first image and the second image to each pixel included in the display surface, to execute the following steps: assigning pixel values ​​based on the first image to at least a portion of pixels observed from the first viewpoint position through the optical element; assigning pixel values ​​based on the second image to at least a portion of pixels observed from the second viewpoint position through the optical element; and assigning a composite pixel value obtained by combining the pixel value based on the first image and the pixel value based on the second image at a predetermined combination ratio, to at least a portion of pixels observed from the first viewpoint position through the optical element and observed from the second viewpoint position through the optical element.

Images