Abstract:
Provided are an image processing device, a method for operating the image processing device, and a system including the image processing device. A method of generating an image of a display system including a projector may include determining first external parameters of the projector, determining second external parameters of the projector in accordance with a variation of the projector, comparing the first external parameters and the second external parameters and calculating a variation amount corresponding to the variation of the projector, and generating a modified input image of the projector on the basis of the variation amount.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present Application is a National Stage entry under 35 U.S.C. §371 of International Application PCT/KR2014/003913, filed May 2, 2014, which claims priority from Korean Patent Application No. 10-2013-0140732, filed in the Korean Patent Office on Nov. 19, 2013. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    Apparatuses and methods consistent with exemplary embodiments relate to an image processing device, an operating method of the image processing device, and a system including the image processing device. 
         [0004]    2. Description of the Related Art 
         [0005]    Recently, glasses type three-dimensional (3D) televisions (TVs) and glasses-free type 3D TVs have become common as 3D content is becoming more readily available. 
         [0006]    Glasses type 3D TVs may provide 3D images to users wearing polarized glasses, which may inconvenience the users by requiring them to wear the glasses, and may cause fatigue during viewing due to an accommodation-vergence conflict. 
         [0007]    Glasses-free type 3D TVs may utilize a viewpoint-based imaging method of providing a multi-view image using a lenticular lens, and the like to display a 3D image, or may utilize a light field-based imaging method of recombining two-dimensional (2D) images separately generated using a scheme of synthesizing light field rays to provide a 3D image. 
         [0008]    In a system utilizing the viewpoint-based imaging method, the resolution of a display decreases based on the number of generated viewpoints, and therefore, the viewing angle and viewing distance are limited. 
         [0009]    A system utilizing the light field-based imaging method may increase the number of projectors disposed corresponding to directional components of light and may secure a required resolution to realize a high-resolution 3D image. 
       SUMMARY 
       [0010]    One or more exemplary embodiments may provide a technology of measuring extrinsic parameters of a projector based on a variation of the projector. 
         [0011]    One or more exemplary embodiments may provide a technology of calculating a variation amount corresponding to the variation of the projector based on a measurement result, calibrating an input image of the projector based on the variation amount and generating a clear three-dimensional (3D) image. 
         [0012]    According to an aspect of an exemplary embodiment, there is provided an image generation method of a display system including a projector, the image generation method including determining at least one first extrinsic parameter of the projector, determining at least one second extrinsic parameter of the projector based on a variation of the projector, calculating a variation amount corresponding to the variation of the projector by comparing the at least one first extrinsic parameter and the at least one second extrinsic parameter, and generating a modified input image of the projector based on the variation amount. 
         [0013]    The calculating of the variation amount may include calculating a rotation angle variation amount corresponding to the variation of the projector by comparing a rotation angle component of the at least one extrinsic parameter and a rotation angle component of the at least one second extrinsic parameter. 
         [0014]    The generating of the modified input image may include rotating the input image in a reverse direction by the rotation angle variation amount and calibrating the input image. 
         [0015]    The generating of the modified input image may include rotating a virtual projector corresponding to the projector by the rotation angle variation amount, acquiring a virtual projection image of the virtual projector using a virtual camera, the virtual projection image being rotated based on the rotating of the virtual projector, and rendering an image acquired using the virtual camera and generating the modified input image. 
         [0016]    The variation may include at least one of a change in a position of the projector and a change in an orientation of the projector. 
         [0017]    The determining the at least one second extrinsic parameter of the projector may include calculating the at least one second extrinsic parameter of the projector based on at least one intrinsic parameter of a camera included in the display system, at least one first extrinsic parameter of the camera, and at least one projection characteristic of the projector. 
         [0018]    The image generation method may further include determining at least one second extrinsic parameter of the camera based on a variation of the camera. The determining of the at least one second extrinsic parameter of the projector may include determining the at least one second extrinsic parameter of the projector based on the at least one intrinsic parameter of the camera, the at least one second extrinsic parameter of the camera, and the at least one projection characteristic of the projector. 
         [0019]    The determining of the at least one first extrinsic parameter of the projector may include measuring the at least one first extrinsic parameter of the projector when the projector is initially installed in the display system. 
         [0020]    The determining of the at least one second extrinsic parameter of the projector may include projecting, by the projector, a checkerboard pattern onto a white board installed in a position of a screen, the checkerboard pattern having a size equal to or less than half a size of the screen, and acquiring a projection image of the projector using a camera included in the display system, analyzing the acquired projection image and thereby determining the at least one second extrinsic parameter of the projector. 
         [0021]    According to an aspect of another exemplary embodiment, there is provided a display system including a projector configured to project light corresponding to an input image, and an image processing device configured to determine at least one first extrinsic parameter of the projector based on a variation of the projector, to compare the at least one first extrinsic parameter and at least one second extrinsic parameter of the projector measured in advance in the display system, to calculate a variation amount corresponding to the variation of the projector, and to generate a modified input image based on the variation amount. 
         [0022]    The image processing device may include a parameter determining unit configured to determine the at least one first extrinsic parameter based on the variation of the projector, an image calibration unit configured to compare the at least one first extrinsic parameter and the at least one second extrinsic parameter, to calculate the variation amount, to calibrate a virtual projection image corresponding to the input image based on the variation amount, and to acquire the calibrated virtual projection image, and an image generation unit configured to generate the modified input image based on an image acquired by the image calibration unit. 
         [0023]    The image calibration unit may be configured to compare a rotation angle component of the at least one first extrinsic parameter and a rotation angle component of the at least one second extrinsic parameter, to calculate a rotation angle variation amount corresponding to the variation of the projector, to rotate the virtual projection image by the rotation angle variation amount, and to calibrate the virtual projection image. 
         [0024]    The image calibration unit may include a virtual projector configured to generate the virtual projection image, the virtual projector corresponding to the projector, a control logic configured to compare the at least one first extrinsic parameter and the at least one second extrinsic parameter, to calculate the variation amount and to rotate the virtual projector in a reverse direction by the variation amount, and a virtual camera configured to acquire the virtual projection image rotated based on rotating of the virtual projector. 
         [0025]    The variation may include at least one of a change in a position of the projector and a change in an orientation of the projector. 
         [0026]    The parameter determining unit may be configured to determine the at least one first extrinsic parameter and the at least one second extrinsic based on at least one intrinsic parameter of a camera, at least one extrinsic parameter of the camera, and at least one projection characteristic of the projector. 
         [0027]    The extrinsic parameters of the camera may be parameters measured based on a variation of the camera. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    These and/or other exemplary aspects and advantages will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings in which: 
           [0029]      FIG. 1  is a block diagram illustrating a display system according to an exemplary embodiment. 
           [0030]      FIG. 2  is a block diagram illustrating the display device of  FIG. 1 . 
           [0031]      FIG. 3  is a block diagram illustrating the image processing device of  FIG. 1 . 
           [0032]      FIG. 4  is a diagram illustrating a scheme of measuring extrinsic parameters of a camera in the parameter measuring unit of  FIG. 3 . 
           [0033]      FIG. 5  is a diagram illustrating a scheme of measuring extrinsic parameters of a projector in the parameter measuring unit of  FIG. 3 . 
           [0034]      FIG. 6  is a block diagram illustrating the image calibration unit of  FIG. 3 . 
           [0035]      FIG. 7  is a diagram illustrating an operation of the image calibration unit of  FIG. 6 . 
           [0036]      FIGS. 8A through 8D  are diagrams illustrating a scheme of generating an input image of a projector based on a variation of a projector. 
           [0037]      FIG. 9  is a flowchart illustrating an operating method of the image processing device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. 
         [0039]      FIG. 1  is a block diagram illustrating a display system according to an exemplary embodiment. 
         [0040]    Referring to  FIG. 1 , a display system  10  includes a display device  100  and an image processing device  200 . The display system  10  may be a glasses-free three-dimensional (3D) display system. 
         [0041]    The display device  100  may generate a 3D image based on an input image received from the image processing device  200 . The input image may be, for example, a two-dimensional (2D) image or a 3D image. The display device  100  may be a light-field 3D display device. 
         [0042]    The image processing device  200  may control the overall operation of the display system  10 . The image processing device  200  may be implemented as an integrated circuit (IC), a system on chip (SoC) or a printed circuit board (PCB), for example, a motherboard. The image processing device  200  may be, for example, a memory and an application processor which operates according to software recorded in the memory. 
         [0043]    The image processing device  200  may generate an input image and transmit the input image to the display device  100  so that the display device  100  may generate a 3D image based on the input image. Also, the image processing device  200  may calculate a variation amount corresponding to a variation of a projector included in the display device  100 , and may generate the input image based on the variation amount. The input image may be, for example, an image calibrated in accordance with the variation amount. 
         [0044]    The image processing device  200  is shown in  FIG. 1  as separate from the display device  100 , however, this is not required. Depending on the embodiment, the image processing device  200  may be included in the display device  100 . 
         [0045]      FIG. 2  is a block diagram illustrating the display device  100  of  FIG. 1 . 
         [0046]    Referring  FIGS. 1 and 2 , the display device  100  may include a projector array  110 , a screen  130 , a plurality of reflection mirrors, for example, a first reflection mirror  153  and a second reflection mirror  155 , and a camera  170 . 
         [0047]    The projector array  110  may include a plurality of projectors  115 . 
         [0048]    Operations of the plurality of projectors  115  are substantially the same, and accordingly, a single projector will be described from  FIG. 2  for convenience of description. 
         [0049]    Each projector  115  may emit at least one ray corresponding to an input image received from the image processing device  200 . The input image may be, for example, an input image for forming a light field image, a multi-view image or a super multi-view image as a 3D image. The input image may be a 2D image or a 3D image. 
         [0050]    Each projector  115  may be an optical module that is a microdisplay including a spatial light modulator (SLM). 
         [0051]    The screen  130  may display the at least one ray projected from the plurality of projectors  115 . For example, a 3D image generated by synthesizing or overlapping the at least one ray may be displayed on the screen  130 . The screen  130  may be a vertical diffusing screen. 
         [0052]    The screen  130  may reflect light and the first reflection mirror  153  and the second reflection mirror  155  may reflect the light, reflected from the screen  130 , among light projected from the projector  115  back into the screen  130 . 
         [0053]    The first reflection mirror  153  may be disposed in one side, for example, a left side of the screen  130 , and may reflect toward the screen light projected to the left side of the screen  130 . The second reflection mirror  155  may be disposed on another side, for example, a right side of the screen  130 , and may reflect toward the screen light projected to the right side of the screen  130 . 
         [0054]    In an example, each of the first reflection mirror  153  and the second reflection mirror  155  may be disposed between the projector array  110  and the screen  130  and may include a reflection surface oriented substantially perpendicular to each of the projector array  110  and the screen  130 . For example, a first end of the first reflection mirror  153  may be adjacent to the projector array  110 , and another end of the first reflection mirror  153  may be adjacent to the screen  130 , and the first reflection mirror itself may be perpendicular to both the projector array  110  and the screen  130 . Also, one end of the second reflection mirror  155  may be adjacent to the projector array  110 , and another end of the second reflection mirror  155  may be adjacent to the screen  130 , and the second reflection mirror  155  may be perpendicular to both the projector array  110  and the screen  130 . 
         [0055]    In another example, the reflection surfaces of first reflection mirror  153  and the second reflection mirror  155  may tilt at a predetermined angle from a center of the screen  130 . In other words, a first end of the first reflection mirror  153  may form a first angle with the projector array  110 , and another end of the first reflection mirror  153  may form a second angle with the screen  130 . One end of the second reflection mirror  155  may form a third angle with the projector array  110 , and another end of the second reflection mirror  155  may form a fourth angle with the screen  130 . For example, the first angle and the third angle may be the same or different. The second angle and the fourth angle may be the same or different. The first reflection mirror  153  and the second reflection mirror  155  may tilt at the predetermined angle from the screen  130 , and may reflect rays projected by the projector  115  toward the screen  130 . For example, the predetermined angle may be set. 
         [0056]    The camera  170  may capture or acquire an image displayed on the screen  130 . The camera  170  may transmit the captured or acquired image to the image processing device  200 . 
         [0057]      FIG. 3  is a block diagram illustrating the image processing device  200  of  FIG. 1 . 
         [0058]    Referring to  FIGS. 1 and 3 , the image processing device  200  may calculate a variation amount corresponding to a variation of the projector  115 , and may generate an input image of the projector  115  based on the variation amount. 
         [0059]    The image processing device  200  may include a parameter measuring unit  210 , an image calibration unit  230 , and an image generation unit  250 . 
         [0060]    The parameter measuring unit  210  may measure camera extrinsic parameters (CEP) CEP 1  and CEP 2  of the camera  170 . The parameter measuring unit  210  may measure first extrinsic parameters CEP 1  of the camera  170 . For example, when the camera  170  is initially installed in the display system  10 , for example, the display device  100 , the parameter measuring unit  210  may measure the first extrinsic parameters CEP 1  of the camera  170 . The parameter measuring unit  210  may measure second extrinsic parameters CEP 2  of the camera  170  based on a variation of the camera  170 . The variation may include at least one of a position variation or an orientation variation of the camera  170  and/or a fixing portion of the camera  170 . By using substantially the same method, the first extrinsic parameters CEP 1  and the second extrinsic parameters CEP 2  of the camera  170  may be measured. The first extrinsic parameters CEP 1  may include parameters measured earlier than the second extrinsic parameters CEP 2 , in addition to parameters measured when the camera  170  is initially installed. The first extrinsic parameters CEP 1  may be, for example, parameters measured in advance in the display device  100 . 
         [0061]      FIG. 4  is a diagram illustrating a scheme of measuring extrinsic parameters of a camera in the parameter measuring unit  210  of  FIG. 3 . 
         [0062]    Referring to  FIG. 4 , the camera  170  may generate a pattern image  330  by capturing a checkerboard pattern of a checkerboard  310  installed in place of the screen  130 . The checkerboard  310  may be, for example, a reference screen disposed in a position corresponding to the position of the screen  130 . The size of the checkerboard  310  may be the same as a size of the screen  130 . 
         [0063]    The parameter measuring unit  210  may correct a distortion of the pattern image  330  acquired using the camera  170 , based on intrinsic parameters of the camera  170 . For example, the intrinsic parameters may be measured outside the display device  100  before the camera  170  is installed in the display device  100 . The intrinsic parameters may include, for example, a distortion coefficient or a camera matrix of the camera  170 . 
         [0064]    The parameter measuring unit  210  may extract, from the pattern image having corrected distortion, a feature point corresponding to an inner corner of the checkerboard pattern, and may calculate a direction vector of the extracted feature point with respect to an optical center of the camera  170 . The parameter measuring unit  210  may measure the first extrinsic parameters CEP 1  of the camera  170  based on the direction vector. For example, the first extrinsic parameters CEP 1  of the camera  170  may include orientation parameters (for example, θx, θy, and θz) and position parameters (for example, x, y and z) of a camera  100  during initial installation of the camera  170 . 
         [0065]    The parameter measuring unit  210  may measure the second extrinsic parameters CEP 2  of the camera  170  based on the variation of the camera  170  using the above-described method. 
         [0066]    The parameter measuring unit  210  may include a memory  215 . The memory  215  may store the first extrinsic parameters CEP 1  and the second extrinsic parameters CEP 2  of the camera  170 . Also, the memory  215  may store intrinsic parameters of the camera  170  of the projector  115 . 
         [0067]    The parameter measuring unit  210  may measure projector extrinsic parameters (PEP) PEP 1  of the projector  115 . The parameter measuring unit  210  may measure first extrinsic parameters PEP 1  of the projector  115 . For example, when the projector  115  is initially installed in the display system  10 , for example, the display device  100 , the parameter measuring unit  210  may measure first extrinsic parameters PEP 1  of the projector  115 . The parameter measuring unit  210  may measure second extrinsic parameters PEP 2  of the projector  115  based on the variation of the projector  115 . The variation may include at least one of a position variation or an orientation variation of the projector  115  and/or an optical axis of the projector  115 . 
         [0068]    By using substantially the same method, the first extrinsic parameters PEP 1  and the second extrinsic parameters PEP 2  of the projector  115  may be measured. The first extrinsic parameters PEP 1  may include parameters measured earlier than the second extrinsic parameters PEP 2 , in addition to parameters measured when the projector  115  is initially installed. For example, the first extrinsic parameters PEP 1  may be parameters measured in advance in the display device  100 . 
         [0069]      FIG. 5  is a diagram illustrating a scheme of measuring extrinsic parameters of a projector in the parameter measuring unit  210  of  FIG. 3 . 
         [0070]    Referring to  FIG. 5 , the projector  115  may project a checkerboard pattern having a size equal to or less than half the size of the screen  130  onto a white board  350  installed in place of the screen  130 . The checkerboard pattern may be input data or an input image of the projector  115 . For example, the white board  350  may be a reference screen disposed in a position corresponding to the position of the screen  130 . 
         [0071]    As shown in  FIG. 5 , a projection image  370  of the projector  115  may be displayed on the white board  350 . 
         [0072]    The camera  170  may generate a pattern image  390  by capturing the checkerboard pattern of the projection image  370  displayed on the white board  350 . 
         [0073]    The parameter measuring unit  210  may correct the distortion of the pattern image  390  acquired using the camera  170  based on intrinsic parameters of the camera  170 . The parameter measuring unit  210  may extract, from the pattern image  390  having corrected distortion, a feature point corresponding to an inner corner of the checkerboard pattern, and may calculate 3D coordinates of the extracted feature point based on the first extrinsic parameters CEP 1  of the camera  170  and a projection characteristic of the projector  115 . For example, the projection characteristic of the projector  115  may be measured outside the display device  100  before the projector  115  is installed in the display device  100 . The projection characteristic of the projector  115  may include, for example, a projection image size and a projection distance of the projector  115 . The projection characteristic may be stored in the memory  215 . 
         [0074]    The parameter measuring unit  210  may measure the first extrinsic parameters PEP 1  of the projector  115  based on the 3D coordinates of the extracted feature point. For example, the first extrinsic parameters PEP 1  may include orientation parameters (for example, θx, θy, and θz) and position parameters (for example, x, y and z) of the projector  115  during initial installation of the projector  115 . 
         [0075]    The parameter measuring unit  210  may measure the second extrinsic parameters PEP 2  of the projector  115  based on the variation of the projector  115  using the above-described scheme. However, when the second extrinsic parameters CEP 2  of the camera  170  are measured based on the variation of the camera  170 , the parameter measuring unit  210  may measure the second extrinsic parameters PEP 2  of the projector  115  based on the measured second extrinsic parameters CEP 2 , instead of the first extrinsic parameters CEP 1  of the camera  170  in the above-described scheme. The second extrinsic parameters PEP 2  of the projector  115  may include orientation parameters and position parameters of the projector  115  which may vary depending on the orientation and position of the projector  115 . 
         [0076]    The image calibration unit  230  may compare the first extrinsic parameters PEP 1  and the second extrinsic parameters PEP 2  of the projector  115 , may calculate a variation amount corresponding to the variation of the projector  115 , and may calibrate a virtual projection image corresponding to the input image of the projector  115  based on the variation amount. For example, the image calibration unit  230  may compare a rotation angle component of the first extrinsic parameters PEP 1  and a rotation angle component of the second extrinsic parameters PEP 2 , may calculate a rotation angle variation amount corresponding to the variation of the projector  115 , and may rotate and calibrate the virtual projection image by the rotation angle variation amount. In this example, the virtual projection image may be rotated in a direction opposite a direction of the rotation angle variation amount. 
         [0077]    Also, the image calibration unit  230  may capture the calibrated virtual projection image. 
         [0078]      FIG. 6  is a block diagram illustrating the image calibration unit  230  of  FIG. 3 , and  FIG. 7  is a diagram illustrating an operation of the image calibration unit  230  of  FIG. 6 . 
         [0079]    Referring to  FIGS. 6 and 7 , the image calibration unit  230  may include a virtual projector unit  233 , a control logic  235 , and a virtual camera  237 . The image calibration unit  230  may further include a memory (not shown). The memory may store the first extrinsic parameters PEP 1  of the projector  115 . 
         [0080]    The virtual projector unit  233  may correspond to the projector array  110  of the display device  100 . The virtual projector unit  233  may include a plurality of virtual projectors. For example, each of the plurality of virtual projectors in the virtual projector unit  233  may correspond to one of the plurality of projectors in the projector array  110 . 
         [0081]    A virtual projector  233 - 1  may project a virtual projection image IM corresponding to an input image of the projector  115 . For example, the virtual projector  233 - 1  may project the virtual projection image IM onto an input image window INPUT_W. The virtual projector  233 - 1  may correspond to the projector  115 . The image processing device  200  may project the virtual projection image IM corresponding to the input image onto the input image window INPUT_W using the virtual projector  233 - 1  corresponding to the projector  115 , to verify a state of the input image before the input image is transmitted to the projector  115 . 
         [0082]    The control logic  235  may compare the first extrinsic parameters PEP 1  and the second extrinsic parameters PEP 2  of the projector  115 , may calculate the variation amount corresponding to the variation of the projector  115 , and may rotate the virtual projector  233 - 1  by the variation amount in a reverse direction. For example, the control logic  235  may compare a rotation angle component of the first extrinsic parameters PEP 1  and a rotation angle component of the second extrinsic parameters PEP 2 , may calculate a rotation angle variation amount corresponding to the variation of the projector  115 , and may rotate the virtual projector  233 - 1  the rotation angle variation amount in a reverse direction by. By rotating the virtual projector  233 - 1 , the virtual projection image IM displayed on the input image window INPUT_W may rotate. For example, the virtual projection image IM may rotate in the reverse direction based on the rotating of the virtual projector  233 - 1 . 
         [0083]    The virtual camera  237  may acquire the virtual projection image IM of the virtual projector  233 - 1 , and may transmit the acquired image to the image generation unit  250 . For example, the virtual camera  237  may acquire the virtual projection image IM rotated by the rotating of the virtual projector  233 - 1 , and may transmit the acquired image to the image generation unit  250 . 
         [0084]    The image generation unit  250  may generate an input image of the projector  115 . The image generation unit  250  may generate the input image based on an image acquired by the virtual camera  237 . The virtual projection image IM, rotated based on the rotating of the virtual projector  233 - 1 , may be acquired. For example, the image generation unit  250  may render the acquired image, and may generate the rendered image as the input image. The image generation unit  250  may be implemented by, for example, a graphics real-time rendering module. 
         [0085]    When the image processing device  200  generates the input image of the projector  115  based on the variation of the projector  115 , the display device  100  may generate a clear 3D image based on the input image regardless of the variation of the projector  115 . 
         [0086]      FIGS. 8A through 8D  are diagrams illustrating a scheme of generating an input image of a projector based on a variation of the projector. 
         [0087]    Referring to  FIGS. 8A through 8D , the parameter measuring unit  210  may measure the second extrinsic parameters PEP 2  of the projector  115  based on the variation of the projector  115 . For example, the parameter measuring unit  210  may measure the second extrinsic parameters PEP 2  of the projector  115  based on intrinsic parameters of the camera  170 , extrinsic parameters (for example, the first extrinsic parameters CEP 1  or the second extrinsic parameters CEP 2 ) of the camera  170 , and the projection characteristic of the projector  115 . An image PM 2  may be a pattern image including a checkerboard pattern captured by the camera  170  when the parameter measuring unit  210  measures the second extrinsic parameters PEP 2 . An image PM 1  may be a pattern image including the checkerboard pattern captured by the camera  170  when the parameter measuring unit  210  measures the first extrinsic parameters PEP 1 . For example, a size of the checkerboard pattern may be equal to or less than half the size of the screen  130 . 
         [0088]    A method by which the parameter measuring unit  210  measures the second extrinsic parameters PEP 2  may be substantially the same as the method described above with reference to  FIG. 5 . 
         [0089]    The parameter measuring unit  210  may transmit the measured second extrinsic parameters PEP 2  of the projector  115  to the image calibration unit  230 , for example, the control logic  235 . 
         [0090]    A current virtual projection image V_IM, corresponding to the input image to be transmitted to the projector  115  based on the variation of the projector  115 , may be displayed on an input image window INPUT_W as shown in  FIG. 8A . 
         [0091]    The control logic  235  may compare the first extrinsic parameters PEP 1  and the second extrinsic parameters PEP 2  of the projector  115 , and may calculate the variation amount corresponding to the variation of the projector  115 . For example, the control logic  235  may compare a rotation angle component of the first extrinsic parameters PEP 1  and a rotation angle component of the second extrinsic parameters PEP 2 , and may calculate a rotation angle variation amount corresponding to the variation of the projector  115 . 
         [0092]    The control logic  235  may rotate the input image of the projector  115  by the variation amount, for example, the rotation angle variation amount, corresponding to the variation of the projector  115 , but in a reverse direction, to calibrate the input image. For example, the control logic  235  may rotate the virtual projector  223 - 1 , corresponding to the projector  115 , by the rotation angle variation amount in a reverse direction. By rotating the virtual projector  223 - 1 , the virtual projection image V_IM may be rotated by the rotation angle variation amount, in the reverse direction, and may be calibrated. 
         [0093]    The virtual camera  237  may acquire the virtual projection image V_IM rotated by rotating the virtual projector  233 - 1 , and may transmit the acquired image to the image generation unit  250 . 
         [0094]    The image generation unit  250  may render the image acquired by the virtual camera  237 , and may generate a rendered image IM 2  as the input image of the projector  115 . An image IM 1  may be an image rendered by the image generation unit  250  before an input image to be transmitted to the projector  115  is calibrated by the rotation angle variation amount corresponding to the variation of the projector  115 . 
         [0095]      FIG. 9  is a flowchart illustrating an operating method of the image processing device  200  of  FIG. 1 . 
         [0096]    Referring to  FIG. 9 , in operation  510 , the image processing device  200  may measure the first extrinsic parameters PEP 1  of the projector  115 . In operation  520 , the parameter measuring unit  200  may measure the second extrinsic parameters PEP 2  of the projector  115  based on the variation of the projector  115 . 
         [0097]    In operation  530 , the image processing device  200  may compare the first extrinsic parameters PEP 1  and the second extrinsic parameters PEP 2  of the projector  115 , and may calculate the variation amount corresponding to the variation of the projector  115 . 
         [0098]    In operation  540 , the image processing device  200  may generate the input image of the projector  115  based on the variation amount. 
         [0099]    One or more methods according to the above-described exemplary embodiments may be recorded in a non-transitory computer-readable medium, and may include program instructions, which, when implemented by a computer cause the computer to perform various operations. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the exemplary embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of non-transitory computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVDs; magneto-optical media such as optical discs; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations of the above-described exemplary embodiments, or vice versa. 
         [0100]    Although a few exemplary embodiments have been shown and described, these are not intended to be limiting. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the inventive concept, the scope of which is defined by the claims and their equivalents.