Source: http://www.google.com/patents/US7787008?dq=5,675,808
Timestamp: 2017-08-17 00:31:00
Document Index: 439619905

Matched Legal Cases: ['Application No. 2002', 'Application No. 2002', 'Application No. 05', 'Application No. 06', 'Application No. 06024697', 'Application No. 2005', 'Application No. 10', 'Application No. 2007', 'Application No. 2007', 'Application No. 2007', 'Application No. 2006101630210', 'Application No. 2006101630193']

Patent US7787008 - Three-dimensional image display device - Google Patents
It is possible to provide a three-dimensional image display device which can improved a final resolution balance and can prevent display blocking. A three-dimensional image display device includes: a two-dimensional image display device where pixels constituting a pixel group displaying an elemental...http://www.google.com/patents/US7787008?utm_source=gb-gplus-sharePatent US7787008 - Three-dimensional image display device
Publication number US7787008 B2
Application number US 11/053,005
Also published as CN1655012A, CN100410728C, DE602005012003D1, EP1566683A1, EP1566683B1, EP1752813A1, EP1754990A1, US20050259323
Publication number 053005, 11053005, US 7787008 B2, US 7787008B2, US-B2-7787008, US7787008 B2, US7787008B2
Inventors Rieko Fukushima, Tatsuo Saishu, Kazuki Taira, Yuzo Hirayama
Patent Citations (20), Non-Patent Citations (20), Referenced by (26), Classifications (18), Legal Events (2)
US 7787008 B2
It is possible to provide a three-dimensional image display device which can improved a final resolution balance and can prevent display blocking. A three-dimensional image display device includes: a two-dimensional image display device where pixels constituting a pixel group displaying an elemental image are arranged in a matrix shape; and an optical plate which has exit pupils corresponding to the pixel group and controls light rays from the pixels of the pixel group, wherein the exit pupils in the optical plate are constituted so as to be continued in an approximately vertical direction, and an angle formed between a direction in which the exist pupils are continued and a column direction of a pixel arrangement in the two-dimensional image display device is given by arctan (1/n) when n is a natural number which is different from multiples of 3.
4. A three-dimensional image display device according to claim 3, wherein a formation region of the elemental image is an approximately square region of n rows×n columns, and RGB sub-pixels having the same parallax number are positioned over three rows of the n rows forming the elemental image, which are different from one another.
5. A three-dimensional image display device according to claim 3, wherein a formation region of the elemental image is an approximately square region of n rows×n columns, and RGB sub-pixels having the same parallax number are positioned over three columns of the n columns forming the elemental image, which are different from one another.
8. A three-dimensional image display device according to claim 1, wherein, when m and l are positive integers, arrangement of RGB sub-pixels having parallax number m and arrangement of RGB sub-pixels having parallax number (m+n×1) are the same.
16. A three-dimensional image display device according to claim 14, wherein a formation region of the elemental image is an approximately square region of n rows×n columns, and RGB sub-pixels having the same parallax number are positioned over three rows of the n rows forming the elemental image, which are different from one another.
17. A three-dimensional image display device according to claim 14, wherein a formation region of the elemental image is an approximately square region of n rows×n columns, and RGB sub-pixels having the same parallax number are positioned over three columns of the n columns forming the elemental image, which are different from one another.
20. A three-dimensional image display device according to claim 10, wherein, when m and l are positive integers, arrangement of RGB sub-pixels having parallax number m and arrangement of RGB sub-pixels having parallax number (m+n×1) are the same.
21. A three-dimensional image display device according to claim 10, wherein, when a plurality of elemental images are viewed through a single column extending over the plurality of elemental images, the parallax number continuously increases upwardly from 1 to N and the increase is repeated.
This application is based upon and claims the benefit of priority from prior Japanese Patent Application Nos. 2004-32973, and 2005-28905 filed on Feb. 10, 2004, and Feb. 4, 2005 in Japan, the entire contents of which are incorporated herein by reference.
Three-dimensional (3-D) image display techniques are classified to various types. When a 3-D image is displayed without using glasses by multiview system, holography, or integral photography system (hereinafter, called “IP system”), for example, the following constitution may be employed. That is, a plurality of pixels for a two-dimensional image display arranged two-dimensionally constitute each of pixels for a 3-D image display, and an optical plate is arranged on a front face of the pixels for a 3-D image display. In the optical plate, an exit pupil designed to be capable of taking only image information or data included in one pixel for a two-dimensional image display from the pixel for a three-dimensional image display is provided for each of pixels for a three-dimensional image display. That is, a viewer can view a three-dimensional image as an autostereoscopic view without using glasses by partially shielding pixels for a three-dimensional image display with the optical plate and making pixels for a two-dimensional image display observed by the viewer through exit pupils different at each viewing position.
In a detailed explanation about the IP system, an image displayed on a pixel for a three-dimensional image display is called “an elemental image”. The elemental image corresponds to a pin-hole camera image shot through a pin hole replacing the exit pupil.
Incidentally, an electronic device is lower in resolution than a silver film for a pin hole camera in the existing circumstances, and the term “elemental image” used in this text simply expresses a collection of pixels constituting plural two-dimensional images with different shot angles. That is, of elemental images displayed on individual pixels for a three-dimensional image display with the above constitution, namely, of a collection of constituent pixels for two-dimensional images (parallax images) shot in a plurality of different directions, only image information pieces coincident with an observing direction of a viewer, namely, only image information pieces which should be viewed when a three-dimensional image is actually present are viewed.
The present invention has been made in view of these circumstances, and an object thereof is to provide a three-dimensional image display device which can improved a final resolution balance and can prevent display blocking.
A formation region of the elemental image can be an approximately square region of n rows×n columns, and RGB sub-pixels having the same parallax number can be positioned over three rows of the n rows forming the elemental image, which are different from one another.
A formation region of the elemental image can be an approximately square region of n rows×n columns, and RGB sub-pixels having the same parallax number can be positioned over three columns of the n columns forming the elemental image, which are different from one another.
When m and l are positive integers, arrangement of RGB sub-pixels having parallax number m and arrangement of RGB sub-pixels having parallax number (m+n×1) can be the same.
FIG. 1 is a diagram showing pixel columns and inclination angles of a region observed by a single eye via a single exit pupil in an optical plate in a two-dimensional image display device in a three-dimensional image display device according to one embodiment of the present invention;
FIGS. 6A and 6B are diagrams showing characteristics according to one embodiment of the invention, FIG. 6A being a diagram showing arrangement of parallax images on a display element using a color filter with a stripe arrangement when an inclination of a single exit pupil in an optical plate is set to arc tan (¼) and FIG. 6B being a diagram showing relative positions among a plurality of elemental images;
FIGS. 7A and 7B are diagrams showing characteristics according to one embodiment of the invention, FIG. 7A being a diagram showing arrangement of elemental images on a display element using a color filter with a stripe arrangement when an inclination of a single exit pupil in an optical plate is set to arc tan (¼) and FIG. 7B being a diagram showing an appearance of an optical plate combined with the elemental images shown in FIG. 7A;
FIG. 8 is a diagram showing how to distribute, to a three-dimensional image display device, pixel information pieces constituting a parallax image acquired from a plurality of different directions at a low resolution by an parallel projection when an inclination of a single exit pupil in an optical plate is set to arc tan (¼) in a three-dimensional image display device according to one embodiment of the invention;
FIG. 9 is a diagram showing arrangement of parallax images on a display element using a color filter with a mosaic arrangement when an inclination of a single exit pupil in an optical plate is set to arc tan (¼) in a three-dimensional image display device according to one embodiment of the invention;
FIG. 10 is a diagram showing arrangement of a plurality of elemental images on a display element using a color filter with a mosaic arrangement when an inclination of a single emit pupil in an optical plate is set to arc tan (¼) in a three-dimensional image display device according to one embodiment of the invention;
FIG. 17 is a diagram showing parallax image numbers viewed via a single exit pupil in an optical plate whose inclination angle is arc tan (¼);
FIG. 25 is a table showing a relationship among the number of parallaxes N, a ratio “a” where a vertical resolution is distributed to a horizontal resolution, and a size of an elemental image when a ratio of lowering in resolution in a horizontal direction is caused to coincide with that in a vertical direction.
Embodiment of the present invention will be explained below with reference to the drawings. In respective figures, constituent elements having similar or identical functions are denoted with same reference numerals and further explanation thereof will be omitted.
H=Horiginal×3÷N÷a
V=Voriginal÷3×a (1)
Here, Horiginal represents a horizontal resolution of a two-dimensional image display device, Voriginal represents a vertical resolution of the two-dimensional image display device, N represents the number of parallaxes, and “a” represents a ratio of the vertical resolution which is distributed to the horizontal resolution by inclining the optical plate.
Horignal:Voriginal=(Horiginal×3÷N÷a):(Voriginal÷3×a)
That is, 3/(N·a)=a/3
Therefore, N=(3/a)2 (2)
Next, a phenomenon where the vertical resolution is distributed to the horizontal resolution by inclining the optical plate will be explained. FIG. 1 is a diagram showing various inclinations of an optical plate to pixels in a two-dimensional image display device. In FIG. 1, reference numeral 3 denotes a region which is observed with a single eye via one of exit pupils continuous in a generally vertical direction of the optical plate 7 whose focus point is caused to coincide on the two-dimensional image display device. The region indicated by the reference numeral 3 shifts in a horizontal direction according to movement of the viewing position. When the exit pupils in the optical plate 7 are formed so as to be continuous vertically in the same manner as the above pixels like the conventional art, pixels (whose centers are coincident with the regions indicated by reference numeral 3) whose centers are viewed via one of the exit pupils in the optical plate 7 are all pixels included in one column or zero, and a cycle where two states are switched from one to the other by movement of the regions indicated by the reference numeral 3 according to movement of a viewer coincides with a horizontal width of a sub-pixel. On the other hand, by inclining the optical plate 7, he number of pixels whose centers can coincide with the regions indicated by the reference numeral 3 is decreased and a cycle where pixels whose centers coincident with the regions appear when the regions indicated by the reference numeral 3 moves according to movement of a viewer becomes shorter than the width of the sub-pixel. Further, the centers of pixels are selected and simultaneously a non-display portion between sub-pixels adjacent to each other in a horizontal direction is present necessarily in the regions indicated by reference numeral 3. In FIG. 1, an example where vertical four rows, vertical five rows, and vertical six rows are respectively inclined to horizontal three columns is shown. The positional relationship between the regions indicated by the reference numeral 3 and the pixels is repeated for every three columns for the vertical four rows, for every four rows for the vertical five rows, and for every one for the vertical six rows. That is, the number of pixels (having the same portion observed via one of exit pupils continuous in a generally vertical direction) having the same relative position to the regions indicated by reference numeral 3 is reduced to ¼, ⅕, and ½. On the other hand, regarding the horizontal direction, pixels whose centers coincide with the regions indicated by the reference numeral 3 appear at a cycle of a ¼ sub-pixel width, a ⅕ sub-pixel width, and a ½ sub-pixel width, as compared with the case that the optical plate is arranged vertically to the pixels. That is, the horizontal resolution is increased to four times, five times, and two times. An advantage obtained by distributing such a resolution to the horizontal resolution and means for preventing the display blocking caused due to the non-display portion have been described in detail in U.S. Pat. No. 6,064,424.
Simultaneously, since one pixel (a triplet) is constituted of three sub-pixels (which do not coincide with one another in the vertical direction) of RGB whose centers are coincident with regions indicated by reference numeral 3 at the 1/n cycle and which are adjacent to one another in the horizontal direction, the ratio “a” where the vertical resolution is distributed to the horizontal resolution is represented as the following equation 4.
That is, in the triplet at a time of three-dimensional image display in the present invention, observation allowable positions for three sub-pixels of RGB slightly deviate from one another (the regions indicated by the reference numeral 3 and the centers of three sub-pixels of RGB do not coincide with each other simultaneously). Therefore, such a coincidence is expressed below as “substantial coincidence” in this text. Since a portions of pixels can be actually viewed via exit pupils in a state where the regions indicated by the reference numeral 3 do not coincide with the centers of pixels, a region where sub-pixels of RGB with the substantial coincidence can be viewed simultaneously is present. In the case shown in FIG. 1, therefore, θ=arc tan (¼), arc tan (⅕), and arc tan (⅙) are obtained, the ratio “a” where the vertical resolution is distributed to the horizontal resolution becomes ¾, ⅗, and ½.
The number of parallaxes N, a ratio “a” where the vertical resolution is distributed to the horizontal resolution, the inclination angle θ of the lens, and the elemental image size to respective natural numbers n are shown in FIG. 25. As understood from FIG. 25, in case of N=9 (n=3), an advantage obtained by distributing the vertical resolution to the horizontal resolution and an advantage of preventing display blocking due to a non-display portion can not be obtained due to the shape of the sub-pixel 2.
(3200×3÷16÷a):(2400÷3×a)=800:600
That is, a=¾→SVGA
(3200×3÷25÷a):(2400÷3×a)=640:480
First of all, in the art disclosed in U.S. Pat. No. 6,064,424, distribution of such a small number of parallaxes as 3, 5, 6, or 7 is made according to such an inclination as θ=arc tan (1/n), (n=6, 9, 12) in a SVGA panel (resolution: 800 (H)×600 (V)) (refer to FIG. 3). Therefore, when calculation is made using the calculation method (the equations (1) to (4) of the embodiment, the horizontal resolution becomes very high. For example, in an example where 6 parallaxes are distributed according to θ arc tan (⅙) (refer to FIG. 2), n=6 is obtained according to the equation (4) and a=½ is obtained according to the equation (3). That is, since the ratio “a” where the vertical resolution is distributed to the horizontal resolution by the inclination is ½,
a=½ is obtained.
That is, (800×3÷6÷a):(600÷3×a)=800:100 is obtained, which results in very high horizontal resolution. Similarly, when 5 parallaxes are distributed according to θ=arc tan (⅙) and 7 parallaxes are distributed to θ=arc tan (⅙), the followings are obtained.
That is, (800×3÷5÷a):(600÷3×a)=960:100
That is, (800×3÷7÷a):(600÷3×a)=685:100
Incidentally, the resolutions in the art described in U.S. Pat. No. 6,064,424 are 480×200 and 342×200, or the ratios of the horizontal resolution to the vertical resolution are 480:200 and 342:200, which are different in value from the above calculations. As the reason, U.S. Pat. No. 6,064,424 describes the fact that such a design that each sub-pixel of RGB constitutes an almost square image in a state that they are viewed via the optical plate is adopted (refer to FIG. 5). In FIG. 5, reference numeral 9 denotes a sub-pixel for a three-dimensional image display. In the art described in U.S. Pat. No. 6,064,424, there is a proposal that three sub-pixels of RGB of RGB sub-pixels constituting almost square pixels in a state the they are viewed via the optical plate which are positioned relatively near to one another are grouped to be handled as one pixel. Even if such handling is employed, the ratio of the horizontal resolution to the vertical resolution such as 480:200 or 342:200 is a resolution balance unique in the art disclosed in U.S. Pat. No. 6,064,424, where a three-dimensional image is not constituted of square pixels of a RGB triplet which has an ordinary pixel shape.
Regarding a pixel mapping for realizing the above design, a case of N=16 in the above-described QUXGA panel will be explained with reference to FIGS. 6A and 6B. FIG. 6A is a diagram showing arrangement of parallax images to a two-dimensional image display device with color filters arranged in a stripe manner when an inclination of a lenticular sheet 7 is set to arc tan (¼), and FIG. 6B is a diagram showing relative positions of a plurality of elemental images. In FIGS. 6A and 6B, reference numeral 10 denotes a parallax number, and reference numeral 11 denotes a diagram showing a range where an exit pupil corresponding to a single pixel which is a constituent unit for a three-dimensional image and an elemental image corresponding thereto are displayed. The number of parallaxes (N=16) and the inclination angle (θ=arc tan (¼)) of an optical plate are determined according to the equations (2) to (4). As a result, the pixel for a three-dimensional image display is defined as a parallelogram (an almost square) constituted of 4 rows×4 pixel (triplet) columns (=a 12 sub-pixel row). RGB sub-pixels are mapped over different rows so as to meet an adoption ratio of ¾ (=a) in the parallelogram. That is, a pixel for a three-dimensional image display constituted of 3 rows (=RGB)×(5+⅓) pixel (triplet) columns (=16 sub-pixel row)=48 sub-pixels when the optical plate was not inclined could be formed in an almost square while maintaining the summed number of sub-pixels.
Since an outer shape of a QUXGA panel of H (3200×3. 16)×V (2400÷3)=H (600)×V (800) has horizontal:vertical=4:3, when the horizontal resolution/the vertical resolution (the number of pixels) meets 4:3, sampling intervals in a horizontal direction and in a vertical direction are the same, so that a pixel shape at a display time of a three-dimensional image becomes square. Here, specifically, the pixel for a three-dimensional image display indicates a region on which an elemental image which is a collection of parallax images constituted of parallax images acquired (shot/prepared) from a plurality of directions. In the number of pixels for a three-dimensional image such as the conventional H (600)×V (800), since sampling intervals in the horizontal direction and in the vertical direction are different from each other (a pixel shape at a display time of a three-dimensional image is not square), the elemental image is composed by preparing parallax images with a resolution of, for example, H (3200×3)×V (2400) and removing unnecessary pixel information elements from these parallax images to change these parallax images to parallax images with a low resolution of H (600)×V (800).
In the embodiment, such a constitution is employed focusing attention on the above waste that parallax images can be acquired with a resolution for a pixel for a three-dimensional image display by reflecting a ratio of a horizontal number of pixels to a vertical number of pixels in screen size and make sampling intervals in the horizontal direction and in the vertical direction equal to each other to make a pixel shape at a display time of a three-dimensional image almost square. That is, in a three-dimensional image display device using the QUXGA panel, parallax images for SVGA panel are acquired in case of 16 parallaxes or parallax images for VGA panel are acquire in case of 25 parallaxes, and an elemental image can be prepared by mapping the parallax images. In this case, parallax image information elements do not include pixel information which is not used (or removed). By forming a pixel for a three-dimensional image display in a square, speed-up in 3D—CG (three-dimensional image computer graphic) contents production can be achieved and lowering in resolution required for actual shooting can be made possible.
FIGS. 7A and 7B are image views of screens viewed by making a pixel for a three-dimensional image display square. FIG. 7A is a view showing a portion of arrangement of elemental images on a two-dimensional image display device with a color filter arranged in a stripe manner when the inclination of the lenticular sheet 7 is set to arc tan (¼), and FIG. 7B is a view showing an appearance of a portion of a lenticular sheet 7 combined with the elemental images. The elemental image 11 is formed in an almost square shape and it is combined with the lenticular sheet 7 so that one pixel for a three-dimensional image display is constituted. Information about 16 parallaxes is included in one pixel for a three-dimensional image display by the picture-mapping in FIGS. 6A and 6B, and the parallax image number viewed through the lenticular sheet is changed from one to another according to movement of a viewing position so that a stereoscopic view is realized.
Next, a method for arranging parallax images acquired from a plurality of directions will be explained with reference to FIG. 8. FIG. 8 is a diagram showing distribution, to respective pixels on a three-dimensional image display device, of image information pieces constituting parallax images acquired from a plurality of directions with a low resolution by parallel projection corresponding to a horizontal direction and by perspective projection corresponding to a vertical direction in a state that an inclination of the optical plate 6 is set to arc tan (¼). In FIG. 8, reference numeral 8 denotes a pixel for a three-dimensional image display observed through a lenticular sheet, reference numeral 12 denotes a parallax image acquired with a resolution of 800 (H)×600 (V) from a certain direction, and reference numeral 13 denotes a pixel (triplet) constituted of three sub-pixels of RGB constituting a two-dimensional image which is a parallax image. The RGB triplet 13 constituting the parallax images 12 acquired from a plurality of directions is mapped as one parallax image for an elemental image constituting each pixel 8 for a three-dimensional image display shown in FIG. 8. A correspondence relationship between the RGB triplets 13 and the pixels 8 for a three-dimensional image display is shown with arrows in FIG. 8. Since one pixel in the three-dimensional image display forms a parallelogram, correspondence to parallax image information can be obtained by shifting a pixel for a three-dimensional image display to the left by one pixel for every four columns of the pixel 8 for a three-dimensional image display. The shift corresponds to one pixel shifting in a three-dimensional image display resolution of 800×400. Therefore, when the three-dimensional image display becomes sufficiently high, the shift can be suppressed to such an extent that a viewer is not nervous about the shift.
The information about a single parallax image has been explained here, but an elemental image corresponding to all pixels for a three-dimensional image display can be prepared by distributing parallax images with a resolution of 800 (H)×600 (V) acquired from a plurality of directions (here, 16 directions) according to FIG. 8→FIGS. 6A and 6B.
On the other hand, FIG. 16 is an explanatory diagram showing parallax numbers viewed through exit pupils in an optical plate when the inclination of the lenticular lens is θ=arc tan (⅙). In this case, parallax images over at least two parallaxes and at most three parallaxes can be viewed via a single exit pupil simultaneously. Hereinafter, a parallax image to be viewed actually is called “a main parallax”, and another parallax image which has been viewed simultaneously with the main parallax is called “an adjacent parallax”.
The lenticular lens is set obliquely in this manner so that the amount of crosstalk is increased and the crosstalk is viewed as a blur. The occurrence of crosstalk eventually restricts a projection display region/a depth display region of contents. Therefore, an example of n=6 meaning a relatively small inclination, namely, an example of a selection ratio of ½ is positively described in U.S. Pat. No. 6,064,424.
FIG. 17 and FIG. 18 are diagrams showing parallax numbers viewed through optical plates set to 0=arc tan (¼) and θ=arc tan (⅕) in this embodiment. As shown in FIG. 17, it is understood that, in the case of θ=arc tan (¼), parallax images appearing as crosstalk correspond to three parallaxes, which is the same as the case of θ=arc tan (⅙), but an occupation ratio of a main parallax image to a plurality of parallax images which can be viewed simultaneously is high. As shown in FIG. 18, it is understood that, in the case of θ=arc tan (⅕), parallax images appearing as crosstalk correspond to three parallaxes, but an occupation ratio of a main parallax image to parallax images is ½ or more. That is, in these inclinations, i.e., in the cases of θ=arc tan (¼) and θ=arc tan (⅕), crosstalk occurs, but a ratio of mixing of adjacent parallax images other than a main parallax image is low so that such an advantage can be obtained that blur is reduced and a projection/depth display region is broadened.
As described above, the present invention includes a novel definition achieving such plural new advantages that 0 # arc tan (⅓ m) including these inclinations (0=arc tan (¼) and θ=arc tan (⅕)) serves not only to prevent display blocking due to the non-display region in the conventional technique but also to maintain a ratio of a horizontal resolution/a vertical resolution and to form a pixel shape at a display time of a three-dimensional image in an almost square, and it serves to facilitate conversion of contents and further expand a display-allowable range in a depth/projection direction by avoiding waste at a time of elemental image preparation and considering an existing resolution in a two-dimensional image display. Further, in the concept disclosed in U.S. Pat. No. 6,064,424, an approach where the horizontal resolution is cut at a pitch of ½ to ¼ time a sub-pixel width (the horizontal resolution is increased to 2 to 4 times and the vertical resolution is decreased to ½ to ¼ time) is employed. On the other hand, in the embodiment, such an approach that the horizontal resolution is cut at a pitch which is not 1/m time such as ¾ time or ⅗ times by selecting three sub-pixels which are positioned in different rows to the same parallax image is employed, which is a novel approach. Moreover, since 2 values of, especially, a=¾ and a=⅗ which are included in a group of a≠⅓ m is a value of ½ or more, a mixing ratio of an adjacent parallax image becomes low and a clear parallax image where crosstalk is further suppressed can be viewed.
In the above, mapping of parallax images has been recommended as shown in FIG. 8 in order to achieve high efficiency for acquiring parallax image information at a time of elemental image preparation. However, a two-dimensional image where pixel arrangement at a display time of a three-dimensional image is maintained may be acquired in order to avoid image degradation due to shifting corresponding to one pixel width of a pixel for a three-dimensional image display in a horizontal direction for every four rows in FIG. 8. That is, the above image degradation can be completely prevented by using parallax images which have a resolution of 800 (H)×600 (V) and are arranged in a matrix manner of parallelogram with an inclination of θ=arc tan (¼) equivalent to the case shown in FIG. 8 instead of using parallax images whose pixel centers constitute a square matrix. This can be realized easily by causing pixel arrangement in a camera used for obtaining a shot image or pixel arrangement in a camera assuming image acquirement in a 3D—CG case to correspond to pixel arrangement for a three-dimensional image display at a display time of a three-dimensional image shown in FIG. 8.
In Example 1, a multiview type three-dimensional image display device with a structure shown in FIG. 19 was manufactured. The two-dimensional image display device 14 was a liquid crystal display device, which was provided at a front face thereof with an optical plate 6 and at a rear face thereof with a back light 16.
Specifically, in the example 1, a QUXGA—LCD panel (the number of pixels of 3200×2400 and a screen size of 480 mm×360 mm) was used as the liquid crystal display device. In the liquid crystal display device 14, three pixels of red color, green color, and blue color can be driven independently. A length of each of the pixels of red, green, and blue in a horizontal or lateral direction was 50 μm and a length thereof in a vertical direction was 150 μm. The color filter arrangement was a stripe arrangement. Incidentally, in an ordinary two-dimensional image display device, one pixel (one triplet) is constituted of three sub-pixels of red, green, and blue colors arranged laterally or horizontally. In this example, such a constraint was released.
A lenticular sheet including lenticular lenses designed such that a pixel position in a liquid crystal display panel corresponded to almost a focal length was used as the optical plate 6. Such a design was employed that a horizontal lens pitch was made slightly narrower than 600 μm which was two times a sub-pixel width and light rays was converged at 16 portions at a viewing distance of 1.0 m with ½ pitch (=32.5 mm) of an inter-eye distance, where a viewing zone at the viewing distance corresponded to the screen width. The lenticular lenses were arranged at an angle deviated from a vertical direction by about 14.0°.
Next, the image producing method will be explained. 16 parallax images (resolution: 800 (×RGB)×600) were acquired by a camera (a virtual camera in CG) from positions of respective converging points of light rays according to a perspective projection. All the image information (800×RGB×600×16 parallax information) acquired was mapped on a QUXGA panel according to mapping shown in FIGS. 6A and 6B. Column information was maintained by performing shifting of one column to the left for every four rows for a pixel for a three-dimensional image display. As shown in FIG. 20, as regards an elemental image on the left end regarding the (4n+1)-th row and the (4n+2)-th row and parallax information about an elemental image on the right end regarding (4n+3)-th row and 4n-th row, portions where their parallax information lacked (mapping could not be performed) occurred. For example, regarding the first to fifth parallax images, data corresponding to one column and one row for constituting an elemental image at the left end on (4n+1)-th row was discarded. Regarding the sixth parallax image information, mapping of only one sub-pixel information corresponding to a color of a sub-pixel distributed with a parallax image number 6 in an elemental image was performed, and similarly mapping of only two sub-pixels information was performed regarding the seventh parallax image. Regarding the eighth parallax image information and parallax images information subsequent thereto, all pixel information was mapped.
When observation was made with the above lens combination after mapping of image information was performed in the above manner, a stereoscopic image of a multiview system could be viewed at a viewing distance of 1.0 m or so (since light rays were converged at ½ of an inter-eye distance, a region where an image was viewed in a stereoscopic manner was also present before and after the viewing distance). In the multiview type three-dimensional image, balance in resolution between a vertical direction and a horizontal direction was improved and contents with a spatial frequency of about 300 cpr could be displayed with a depth of the maximum about ±5 cm before and after the display plane by inclining the lens. Though screen luminance change due to the non-display portion occurred according to movement of a viewing position, occurrence of luminance unevenness within the screen (moire) was suppressed.
In Example 2, an IP type three-dimensional image display device with the structure shown in FIG. 19 was manufactured. By designing a pitch of an exit pupil of an optical plate to an integral multiple a sub-pixel pitch in the image display device, such a constitution was achieved that a converging point of light rays did not occur in a viewing distance, which was different from the multiview system. Differences between Example 2 and Example 1 will be explained below.
Design was made that a horizontal pitch of a lens was four times a sub-pixel width, i.e, 600 μm, and a viewing range was ±15° . Thereby, the viewing range (a region could be viewed without mixing a quasi image) corresponding to a screen width at a viewing distance of 1.0 m could be secured. An inclination of a lens was about 14.0°. 28 parallax images whose horizontal directions were applied with parallel projection and whose vertical directions were applied with perspective projection were acquired at the viewing distance by setting a target point on a center of a screen and using a camera (a virtual camera in CG). Because a converging point of light rays were not provided at the viewing distance, in the IP system where perspective projection images obtained at the viewing distance could not be used, when the viewing region was intended to be maximized at the viewing distance, the number of parallax images acquired (the number of positions of a camera acquiring an image) became more than that obtained in the multiview system where a converging point of light rays was provided at the viewing distance. In the embodiment where light rays becomes parallel between adjacent exit pupils, the number of parallel projection parallax images (camera images) obtained increases to the standard number of parallaxes (=16). As to the details thereof, refer to Japanese Patent Application No. 2002-382389 which was assigned to the present assignee. Here, parallax images were acquired with a resolution of 800 (× RGB)×600 from 28 directions. 800×RGB×600×28 parallax information was basically mapped according to the mapping shown in FIG. 6. Incidentally, in the IP system where parallax is taken in consideration, design of elemental image width>exit pupil pitch can be made in a pseudo manner by interposing an elemental image with (the standard number of parallaxes+1) parallaxes discretely such that image information from each elemental image can be viewed within the viewing region. FIG. 21 shows one example of the design. After mapping including parallax image numbers 1 to 16 shown in FIG. 21 is repeated plural times, mapping including parallax image numbers 1 to 17 shown in FIG. 22 occurs. Thereafter, an elemental image which has the same area as that shown in FIG. 21 but includes parallax image numbers 2 to 17 is repeated, but a shape thereof is slightly different from that shown in FIG. 21 (refer to FIG. 23).
When all 28 parallax images are acquired at the same resolution of 800 (H)×600 (V) due to such a fact that this system is an IP system, image information which is not used occurs substantially (As to the details thereof, refer to Japanese Patent Application No. 2002-382389 which was assigned to the present assignee). In addition thereto, there occurs a portion from which parallax information about elemental images at both ends of a screen is discarded like the first example (refer to FIG. 20).
This IP system was slightly complicated as compared with the multiview system, but when observation was made with mapping of image information with a resolution of 800×600 and the combination of lenses described above, a stereoscopic image of an IP system could be viewed in a viewing region based on a viewing distance of 1 m. The IP system three-dimensional image was improved in a vertical/horizontal resolution balance so that image quality was improved and depth display of at most ±5 cm before and after the display plane could be made possible. Any luminance unevenness (moire) within a screen due to a non-display portion was not viewed and luminance change depending on a viewing position could be suppressed completely. A smooth kinematic parallax which was a feature of the IP system where a converging point of light rays was not present at the viewing distance could be realized.
Example 3 was approximately similar to the example 2, but it adopted such a design that the standard number of parallaxes was increased to 25. A lenticular lenses designed such that a pixel position on a liquid crystal display panel was a focal length was used as the optical plate. A horizontal pitch of a lens was set to 750 μm which was 15 times a sub-pixel width and an inclination of the lenticular sheet was set to about 11.3°.
At a viewing distance, 44 parallax images whose horizontal directions and vertical directions were applied with parallel projection were acquired at the viewing distance by setting a target point on a center of a screen and using a camera (a virtual camera in CG). A resolution of the parallax image had a resolution of 640 (×RGB)×480. Mapping of 640×RGB×480×25 parallax information was basically performed according to the mapping shown in FIG. 8. As shown in FIG. 12, column information was maintained by shifting three-dimensional image display pixels to the left by a width of the three-dimensional image display pixel for every five rows thereof. Two elemental images at left ends of the (5n+1)-th and the (5n+2)-th rows, an elemental image at both ends of the (5n+3)-th row, and two elemental images at right ends of the (4n+4)-th and the 5n-th rows included portions where parallax information was lacking (mapping could not be performed).
This IP system was slightly complicated as compared with the multiview system, but when observation was made with mapping of image information with a resolution of 640×480 and the above-described combination of lenses, a stereoscopic image of an IP system could be viewed in a viewing region based on a viewing distance of 1.0 m. The IP system three-dimensional image was improved in a vertical/horizontal resolution balance so that image quality was improved and depth display of at most about ±15 cm before and after the display plane could be made possible. Any luminance unevenness (moire) within a screen due to a non-display portion was not viewed and luminance change depending on a viewing position could be suppressed completely. A smooth kinematic parallax which was a feature of the IP system where a converging point of light rays was not present at the viewing distance could be realized.
Example 4 was approximately similar to Example 2, but it adopted a display panel having a color filter with a mosaic arrangement. Differences between Example 4 and Example 2 will be explained below.
Regarding 28 parallax images acquired at a resolution of 800 (×RGB)×600, 800 (×RGB)×600×28 parallax image was mapped according to the mapping shown in FIG. 9. In the IP system, elemental images of (the standard number of parallaxes+1) parallaxes were generated discretely such that image information from each elemental image could be viewed within a viewing range. When observation was made with a combination thereof with a lens, a stereoscopic image of an IP system could be viewed within a viewing range based upon a viewing distance of 1 m.
The IP system three-dimensional image was improved in a vertical/horizontal resolution balance so that image quality was improved and depth display of at most about ±5 cm before and after the display plane could be made possible. Any luminance unevenness (moire) within a screen due to a non-display portion was not viewed and luminance change depending on a viewing position could be suppressed completely. A smooth kinematic parallax which was a feature of the IP system where a converging point of light rays was not present at the viewing distance could be realized. Further, since the color filter with the mosaic arrangement was employed, R, B or G viewed through the lenticular sheet were further dispersed, so that there was a tendency that display blocking due to continuation of regions which were viewed as R, B, or G could be suppressed.
In a three-dimensional image display device of a multiview system similar to Example 1, an inclination of a lens was changed to 9.5° which was equivalent to the art disclosed in U.S. Pat. No. 6,064,424, a horizontal width of a lens was correspondingly set to 400 μm equal to 8 sub-pixels width which was ½ a width of 16 sub-pixels, and corresponding mapping was performed like that in the art disclosed in U.S. Pat. No. 6,064,424. In this design, a resolution in the three-dimensional image was follows:
“a”=½,
therefore, (3200×3÷16÷a):(2400÷3×a)=1200:400.
That is, the horizontal resolution became higher than the vertical resolution. Accordingly, parallax images with a resolution of H (1200)×V (900) were acquired and horizontal information was acquired at a rate of 4/9 (it was discarded at a rate of 5/9), so that mapping of image information was performed. That is, a time for image production was required excessively corresponding to acquisition of waste parallax image information and a large memory capacity was required for temporarily storing respective parallax image data elements acquired from plural directions. A balance in resolution of an image displayed was bad, which impressed poor vertical information relative to horizontal information. An amount of crosstalk was larger than that in Examples, and a depth display was suppressed to ±3 cm before and after the display plane. When contents with an existing resolution was displayed, it was necessary to modify the existing resolution to a resolution of H (1200)×V (400), which resulted in a device with a poor versatility.
In a three-dimensional image display device of a multiview system similar to Example 2, an inclination of a lens was set to 18.4°. When the inclination was employed, an advantage obtained by distributing a vertical resolution to a horizontal resolution can not be obtained. Therefore, a horizontal width of a lens was set to 800 μm equal to a width of 16 sub-pixels, and corresponding mapping (RGB sub-pixels continuous obliquely were grouped) was performed. In this design, a resolution in the three-dimensional image was as follows:
“a”=1,
therefore, (3200×3÷16÷a):(2400÷3×a)=600:800.
That is, the vertical resolution became higher than the horizontal resolution. Accordingly, parallax images with a resolution of H (1600)×V (1200) were acquired, and only ⅜ of data in a horizontal direction and ⅔ of data in a vertical direction were acquired, while the remaining data was discarded, so that mapping of image information was performed. That is, a time for acquiring parallax image information was excessively required corresponding to data to be discarded. A balance in resolution of an image displayed was bad, which impressed poor horizontal information relative to vertical information. When contents with an existing resolution was displayed, it was necessary to modify the existing resolution to a resolution of H (600)×V (800), which resulted in a device with a poor versatility.
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U.S. Classification 348/51, 349/15
International Classification H04N13/04, G02F1/1335, H04N13/00, G02B27/22
Cooperative Classification H04N13/0452, G02B27/2214, H04N13/0415, H04N13/0422, H04N13/0409, H04N13/0404
European Classification H04N13/04A3, H04N13/04B, H04N13/04M, H04N13/04A1, H04N13/04A4, G02B27/22L
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:FUKUSHIMA, REIKO;SAISHU, TATSUO;TAIRA, KAZUKI;AND OTHERS;REEL/FRAME:016857/0604