Abstract:
According to the present disclosure, there is disclosed a method and device for displaying a 3-dimensional image, which may provide an improved depth perception. The method according to present invention comprises: forming parallax images for left eye and right eye, each of the parallax images including a plurality of images corresponding to images at different depths for a same object; controlling a brightness of the images of each of the parallax images for the left eye and the right eye; and displaying the parallax images for the left eye and the right eye.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority from Korean Patent Application No. 10-2010-9858 filed on Feb. 3, 2010, the entire subject matter of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure generally relates to a device and method for displaying images, and more particularly to a device and method for displaying 3-dimensional images. 
       BACKGROUND 
       [0003]    Several methods for displaying a 3-dimensional image in conventional display devices are currently known in the art. One of such methods is a stereoscopic display method, which provides a depth perception of 3-dimensional display from a 2-dimensional screen. The stereoscopic display method uses an image parallax between left and right images to provide the depth perception at the 2-dimensional screen. However, since parallax information may be changed only by a pixel unit according to the resolutions of a camera for obtaining the image and a display device, it is difficult to express minute changes in the parallax information within one pixel. Thus, there is a limitation in reducing the minimum unit of depth variation, which may be expressed through the parallax information. 
         [0004]    Another method of 3-dimensional image display is a depth fused 3D (DFD) display method, which shows a plurality of 2-dimensional images overlapped with each other by arranging a plurality of displays back and forth. The DFD display method controls the depth perception of the 3-dimensional image through changing the brightness ratio of, for example, two 2-dimensional images on two respective displays arranged back and forth. This method can express minute changes in the parallax information by utilizing two flat panel display devices to implement a 3-dimensional image. However, the DFD method has some problems in that the presentable depth is limited within the gap between the two display devices and the size of the entire device is too large due to the physical distance between the two display devices. 
       SUMMARY 
       [0005]    The present invention is designed to solve the above-mentioned problems of conventional technologies. The purpose of the present invention is to provide a 3-dimensional image display device and a method of implementing the same, which may improve the resolution of depth of a stereoscopic 3-dimensional image. 
         [0006]    According to one aspect of the present invention, a method of displaying a 3-dimensional image comprises forming projections of virtual images of an object at different observation depths onto a display panel; forming a first parallax image for a left eye and a second parallax image for a right eye based on the projections; and displaying the first and second parallax images. 
         [0007]    According to another aspect of the present invention, a method of displaying a 3-dimensional image comprises: forming a first parallax image for a left eye and a second parallax image for a right eye, each of the first and second parallax images including a plurality of display images, said plurality of display images corresponding to projections of virtual images of an object at different depths as viewed by the respective eye; controlling a brightness of each of the plurality of display images in each of the first and second parallax images; and displaying the first and second parallax images. 
         [0008]    According to yet another aspect of the present invention, the 3-dimensional image display device comprises: an image forming unit configured to form a first parallax image for a left eye and a second parallax image for a right eye, each of the first and second parallax images including a plurality of display images, said plurality of display images corresponding to projections of virtual images of an object at different depths as viewed by the respective eye; an image brightness control unit configured to control a brightness of each of the plurality of display images in each of the first and second parallax images; and an image display unit configured to display the first and second parallax images. 
         [0009]    According to one embodiment of the present invention, a 3-dimensional image display device and a method capable of enlarging the resolution of depth of a 3-dimensional image by changing the brightness of images on a display panel for each of left and right parallax images may be provided. In addition, according to one embodiment of the present invention, a 3-dimensional image display device and a method capable of expressing minute parallax information may be provided as the parallax information may be changed without being limited to a pixel unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a block diagram of a 3-dimensional image display device according to one embodiment of the present invention. 
           [0011]      FIG. 2  is a conceptual diagram showing how an image is formed by an image forming unit according to one embodiment of the present invention. 
           [0012]      FIGS. 3   a - 3   c  are a diagram showing how the brightness of images is controlled by an image brightness control unit according to one embodiment of the present invention. 
           [0013]      FIG. 4  is a flow diagram of a method for displaying a 3-dimensional image according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Embodiments of the present invention are described below with reference to the accompanying drawings. To simplify the description and not to obscure unnecessarily the invention, well-known features and configurations are not described below. Also, although the below description is related to one embodiment of the present invention, it is to be understood that the present invention is not limited to that. 
         [0015]      FIG. 1  is a block diagram of a 3-dimensional image display device  100  according to one embodiment of the present invention. As shown in  FIG. 1 , the 3-dimensional image display device (“display device”)  100  comprises an image forming unit  120 , an image brightness control unit  140  and an image display unit  160 . The image forming unit  120  forms images that are provided to each of the left and right eyes of a viewer according to a predetermined algorithm. A conceptual diagram showing how an image is formed by the image forming unit  120  according to one embodiment of the present invention is shown in  FIG. 2 . 
         [0016]    Referring to  FIG. 2 , the image forming unit  120  forms display images  222 ,  224 ,  232  and  234  located on one display panel  210 . In the present disclosure, the positions of the display images  222 ,  224 ,  232  and  234  are determined by projecting virtual images  262  and  272  on first and second virtual display panels  260  and  270  onto the display panel  210 , assuming that the first and second virtual display panels  260  and  270  are positioned separate from each other by a predetermined distance. In one embodiment, the virtual images  262  and  272  on the first and second virtual display panels  260  and  270  are of the same object. In one embodiment, the display images  222 ,  224 ,  232  and  234  are provided on the display panel  210  such that the viewer may perceive the display images  222 ,  224 ,  232  and  234  as the same size considering the distortion of the rendered space. The display images  222  and  232  correspond to the projections of the virtual image  262  on the first virtual display panel  260 . Further, the display images  224  and  234  correspond to the projections of the virtual image  272  on the second virtual display panel  270 . The display images  222  and  224  are provided to the left eye  220 , while the display images  232  and  234  are provided to the right eye  230 . Although the display images  222  and  224  for the left eye  220  are shown to overlap each other and the display images  232  and  234  for the right eye  230  are shown to overlap each other in  FIG. 2 , it will be readily understood by those skilled in the art that the display images  222 ,  224 ,  232  and  234  may or may not overlap each other. 
         [0017]    Referring back to  FIG. 1 , the image brightness control unit  140  controls the brightness of the display images  222 ,  224 ,  232  and  234  formed by the image forming unit  120 . The brightness of the display images  222 ,  224 ,  232  and  234  are controlled by utilizing a method used in the conventional DFD method.  FIGS. 3   a - 3   c  are diagrams showing how the brightness of the display images  222 ,  224 ,  232  and  234  is controlled by the image brightness control unit  140  according to one embodiment of the present invention. For purposes of description, the display images  222 ,  224 ,  232  and  234  are shown as not overlapping with each other. In  FIG. 3   a , the display images  222  and  232  corresponding to the projections of the virtual image  262  on the first virtual display panel  260  and the display images  224  and  234  corresponding to the projections of the virtual image  272  on the second virtual display panel  270  have the same brightness. In this case, the viewer perceives the depth as a 3-dimensional image  250  and is placed at the middle of the two virtual display panels  260  and  270 . 
         [0018]    In  FIG. 3   b , the display images  222  and  232  corresponding to the projections of the virtual image  262  on the first virtual display panel  260  have a brightness ratio of 100%. However, the display images  224  and  234  corresponding to the projections of the virtual image  272  on the second virtual display panel  270  have a brightness ratio of 0% (i.e., the display images  224  and  234  corresponding to the projections of the virtual image  272  on the second virtual display panel  270  are not displayed). In such a case, the viewer perceives the depth as the 3-dimensional image and is placed at depth of the first virtual display panel  260 . In  FIG. 3   c , the display images  222  and  232  corresponding to the projections of the virtual image  262  on the first virtual display panel  260  have a brightness ratio of 0% (i.e., the display images  222  and  232  corresponding to the projections of the virtual image  262  on the second virtual display panel  260  are not displayed). However, the display images  224  and  234  corresponding to the projections of the virtual image  272  on the second virtual display panel  270  have a brightness ratio of 100%. In this case, the viewer perceives the depth as the 3-dimensional image and is placed at depth of the second virtual display panel  270 . 
         [0019]    As such, the image brightness control unit  140  controls the brightness of the display images  222  and  232  corresponding to the projections of the virtual image  262  on the first virtual display panel  260  to be the same as each other. It also controls the brightness of the display images  224  and  234  corresponding to the projections of the virtual image  272  on the first virtual display panel  270  to be the same as each other. It is to be understood that the depth of the 3-dimensional image  250  perceived by the viewer may be changed when the brightness of the display images  222 ,  224 ,  232  and  234  is adjusted by the image brightness control unit  140 . In one embodiment, the 3-dimensional image  250  will be perceived to be at the depth closer to the first virtual display panel  260  as the brightness of the display images  222  and  232  corresponding to the projections of the virtual image  262  on the first virtual display panel  260  is brighter than the brightness of the display images  224  and  234  corresponding to the projections of the virtual image  272  on the second virtual display panel  270 . 
         [0020]    Referring back to  FIG. 1 , the image display unit  160  displays the display images, the brightness of which has been adjusted. In one embodiment, the image display unit  160  displays the brightness-adjusted images  222  and  224  or  232  and  234  together by using a brightness division method. The brightness division method first halves the brightness of each of the display images  222  and  224  or  232  and  234 , and then combines the brightness of each of the display images  222  and  224  or  232  and  234  to display. When the brightness of the two display images  222  and  224  or  232  and  234  is combined to display, the viewer perceives that the two display images  222  and  224  or  232  and  234  are displayed concurrently. In one embodiment, the two display images  222  and  224  or  232  and  234  may be translucent similar to the conventional DFD method. 
         [0021]    In another embodiment, the image display unit  160  displays the brightness-adjusted images  222  and  224  or  232  and  234  by using a time division method. The time division method displays the two display images  222  and  224  or  232  and  234  alternately. When the two display images  222  and  224  or  232  and  234  are displayed alternately with a fast refresh rate, the viewer perceives that the two display images  222  and  224  or  232  and  234  are displayed concurrently. Preferably, the refresh rate may be, for example, 120 Hz, which is twice as fast as a normal display device. In one embodiment, the two display images  222  and  224  or  232  and  234  may be translucent similar to the conventional DFD method. 
         [0022]    In one embodiment, the distance between the two display images  222  and  224  or  232  and  234  may be the size of one unit pixel of the screen. While the minimum range of variation of parallax information was limited to the pixel unit according to the resolution of the display device in the conventional technology, the present invention may express minute parallax information since the parallax information can be changed within one pixel. 
         [0023]      FIG. 4  shows a flow diagram of the method for displaying a 3-dimensional image according to one embodiment of the present invention. In step  410 , the display images  222 ,  224 ,  232  and  234  are formed on the display panel by the image forming unit  120 . The display images  222  and  232  correspond to the projections of the virtual image  262  on the first virtual display panel  260 . Further, the display images  224  and  234  correspond to the projections of the virtual image  272  on the second virtual display panel  270 . In step  420 , the brightness of the formed display images is controlled by the image brightness control unit  140 . In one embodiment, the depth perception of the 3-dimensional image may be controlled by adjusting the brightness. For example, the 3-dimensional image  250  will be perceived to be at the depth closer to the first virtual display panel  260  as the brightness of the display images  222  and  232  corresponding to the projections of the virtual image  262  on the first virtual display panel  260  is brighter than the brightness of the display images  224  and  234  corresponding to the projections of the virtual image  272  on the second virtual display panel  270 . In step  430 , the display images are displayed by the display unit  160 . In one embodiment, the image display unit  160  displays the brightness-adjusted images  222  and  224  or  232  and  234  together by using the brightness division method. In the brightness division method, the brightness data of the display images  222  and  224  for the left eye, for example, are first halved, and then the brightness data of the images  222  and  224  are combined and outputted when displaying. As such, the viewer perceives that the two display images  222  and  224  are provided concurrently. In another embodiment, the image display unit  160  displays the brightness-adjusted images  222  and  224  or  232  and  234  by using the time division method. In the time division method, the display images  222  and  224  for the left eye, for example, are displayed alternately. As such, the viewer perceives that the two display images  222  and  224  are provided concurrently. It is decided according to a predetermined algorithm whether to use the brightness division method or the time division method. In one embodiment, the algorithm considers the characteristics such as the rate of the display device in determining whether to use the brightness division method or the time division method. 
         [0024]    In the above description, each of the parallax images for the left eye  220  and the right eye  230  are shown to be provided through the display panel  210  in order to simplify the description. However, it will be readily understood by those skilled in the art that the conventional stereoscopic or autostereoscopic methods (e.g., polarized glasses, head mounted display (HMD), parallax barrier, lenticular lens, etc.) may be used to provide parallax images for each eye. In addition, the device and method of displaying a 3-dimensional image according to the present invention may be applied to a multiview or super-multiview display. The images shown on the display panel  210  for providing the parallax image to both eyes  220  and  230  of the viewer according to the present invention may vary according to the parallax image providing method used. 
         [0025]    Since the present invention utilizes two virtual display panels represented on one display panel rather than two physical display panels, the two virtual display panels may be configured to be infinitely separated from each other. Thus, they may express an infinite depth perception without the limitation on depth expression of conventional DFD methods. Also, while conventional stereo display devices provide a 3-dimensional image using only the parallax of left and right images, the present invention may express the depth variation within one pixel through the change in the brightness rate of each image. 
         [0026]    Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.