Abstract:
Disclosed herein is an apparatus for correcting image distortion of a lens, including an input unit for receiving image information, a segmentation unit for segmenting the image information into one or more image subdivision units, a setting unit for setting a center of the image information, a controller for shifting each of the one or more image subdivision units by a variation ratio with respect to the center of the image information, an interpolation unit for inserting one or more image subdivision units corresponding to the shifted image subdivision units into an interpolation space generated between the shifted image subdivision units, and an output unit for outputting corrected image information. According to an embodiment of the present invention, by shifting one or more image subdivision units by a variation ratio, operation logic for coordinate calculation and internal memory logic may be minimized, and implementation complexity may be lowered.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2015-0127931, filed on Sep. 9, 2015, entitled “APPARATUS FOR REVISING IMAGE DISTORTION OF LENS”, which is hereby incorporated by reference in its entirety into this application. 
       BACKGROUND 
       [0002]    Technical Field 
         [0003]    The present invention relates to an apparatus for correcting image distortion of a lens, and more particularly, to an apparatus for correcting image distortion of a lens that shifts images of image subdivision units by a variation ratio. 
         [0004]    Description of the Related Art 
         [0005]    The technology of correcting image distortion of a lens is directed to correcting image distortion of a lens having a wide angle of view and is widely used in the fields of endoscopes and automobiles. 
         [0006]    In particular, in the field of automobiles, the surroundings of a vehicle may be checked through eyes or side view mirrors. For some automobile models, it is easy to check the surroundings of the automobiles through eyes or side view mirrors. For other automobile models, however, it is not easy to check the surroundings of the automobiles through eyes or side view mirrors. In particular, large vehicles have a relatively large number of areas which cannot be checked simply through eyes or side view mirrors, compared to small vehicles. 
         [0007]    In this regard, a technology for capturing images of the surroundings of a vehicle using a rear camera mounted to the vehicle or cameras installed at the front, back, left side and right side of the vehicle and outputting an around view image by combining the captured images have been developed. The cameras installed at the front, back, left side, and right side of a vehicle usually employ wide-angle lenses having a wide angle of view and even a fish-eye lens, whose angle of view is greater than 180°. Images captured using lenses having a wide angle of view such as a wide-angle lens and fish-eye lens provide wide views, but a refraction rate increases toward the edges of the images, resulting in severely distorted images. Accordingly, there is a need for a method for correcting distortion of images captured using lenses having a wide angle of view such as a wide-angle lens and fish-eye lens. 
         [0008]      FIG. 1  illustrates a procedure of correcting an image in a conventional apparatus for correcting image distortion of a lens. 
         [0009]    Referring to  FIG. 1 , methods for correcting distorted images in a conventional apparatus for correcting image distortion of a lens include distortion correction using a mathematical model and distortion correction using a Cartesian coordinate pattern. When the Cartesian coordinate pattern is used, a distorted image  110  is corrected by shifting each pixel  111 . 
         [0010]    When the mathematical model is used, coordinates of pixels  121  after correction are obtained by putting the coordinates of each pixel  111  in a predetermined equation, and a corrected image  120  is acquired by arranging the pixels  121 . In this case, as the same equation is applied to all pixels, it is difficult to consider the degree of distortion. In addition, since calculation needs to be performed for all pixels, implementation complexity is high and the memory of a large capacity is required. 
         [0011]      FIG. 2  illustrates a procedure of correcting a distorted image using a conventional Cartesian coordinate pattern. 
         [0012]    Referring to  FIG. 2 , according to the method for correcting a distorted image using the Cartesian coordinate pattern, relationship information  230  about the relationship between the coordinates of some pixels before distortion correction and the coordinates of some corresponding pixels after correction is acquired. In this case, since the relationship information  230  is acquired using only some pixels, the capability of distortion correction is low. Further, since all pixel values before and after correction need to be stored, a memory having a large capacity is required. 
       SUMMARY 
       [0013]    It is an aspect of the present invention to provide an apparatus for correcting image distortion of a lens which may minimize operation logic and internal memory logic and lower implementation complexity. 
         [0014]    It should be noted that objects of the present invention are not limited to the aforementioned object, and other objects of the present invention will be apparent to those skilled in the art from the following descriptions. In addition, it will be appreciated that the objects and advantages of the present invention can be implemented by means recited in the appended claims and the combination thereof. 
         [0015]    In accordance with one aspect of the present invention, an apparatus for correcting image distortion of a lens includes an input unit for receiving image information, a segmentation unit for segmenting the image information into one or more image subdivision units, a setting unit for setting a center of the image information, a controller for shifting each of the one or more image subdivision units by a variation ratio with respect to the center of the image information, an interpolation unit for inserting one or more image subdivision units corresponding to the shifted image subdivision units into an interpolation space generated between the shifted image subdivision units, and an output unit for outputting corrected image information. 
         [0016]    In accordance with another aspect of the present invention, an apparatus for correcting image distortion of a lens includes an input unit for receiving image information, a setting unit for setting a center of the image information, a segmentation unit for segmenting the image information into predetermined units with respect to the center, a controller for correcting distortion of each of the segmented predetermined units of the image information, and an output unit for outputting corrected image information. 
         [0017]    According to an embodiment of the present invention, by shifting one or more image subdivision units by a variation ratio, operation logic for coordinate calculation and internal memory logic may be minimized, and implementation complexity may be lowered. 
         [0018]    According to an embodiment of the present invention, by inserting image subdivision units into an interpolation space generated between shifted image subdivision units, high-definition images may be processed. 
         [0019]    According to an embodiment of the present invention, the capability of distortion correction may be maximized by changing the variation ratio. 
         [0020]    According to an embodiment of the present invention, by moving the center of image information or segmenting the image information into predetermined units, the image information may be corrected according to the degree of distortion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  illustrates a procedure of correcting an image in a conventional apparatus for correcting image distortion of a lens. 
           [0022]      FIG. 2  illustrates a procedure of correcting a distorted image using a conventional Cartesian coordinate pattern. 
           [0023]      FIG. 3  is a diagram schematically illustrating configuration of an apparatus for correcting image distortion of a lens according to an embodiment of the present invention. 
           [0024]      FIG. 4A ,  FIG. 4B  and  FIG. 4C  illustrate a procedure of correcting a distorted image in an apparatus for correcting image distortion of a lens according to an embodiment of the present invention. 
           [0025]      FIG. 5  schematically illustrates image subdivision units and the center of image information given before distortion correction. 
           [0026]      FIG. 6  illustrates a procedure of inserting image subdivision units into horizontally shifted image subdivision units. 
           [0027]      FIG. 7  illustrates a procedure of inserting image subdivision units into vertically shifted image subdivision units. 
           [0028]      FIG. 8  illustrates a procedure of correcting a distorted image in an apparatus for correcting image distortion of a lens according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    The aforementioned objects, advantages and features of the invention will be set forth in detail with reference to the accompanying drawings such that those skilled in the art can easily practice the present invention. In describing embodiments disclosed in this specification, relevant well-known technologies may not be described in detail in order not to obscure the subject matter of the present invention. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals are used to refer to the same or like elements throughout the drawings. 
         [0030]      FIG. 3  is a diagram schematically illustrating configuration of an apparatus for correcting image distortion of a lens according to an embodiment of the present invention. 
         [0031]    Referring to  FIG. 3 , an apparatus  300  for correcting image distortion of a lens according to an embodiment of the present invention may include an input unit  310 , a segmentation unit  320 , a setting unit  330 , a controller  340 , an interpolation unit  350 , and an output unit  360 . 
         [0032]    The apparatus  300  for correcting image distortion shown in  FIG. 3  is simply an embodiment, and elements thereof are not limited to the embodiment shown in  FIG. 3 . When necessary, some elements may be added, changed or omitted. 
         [0033]      FIG. 4A, 4B and 4C  illustrate a procedure of correcting a distorted image in the apparatus  300  for correcting image distortion of a lens according to an embodiment of the present invention, and  FIG. 5  schematically illustrates image subdivision units  510  to  519  and  520  to  529  and the center  502  of image information  501  given before distortion correction. 
         [0034]      FIG. 6  illustrates a procedure of inserting image subdivision units into horizontally shifted image subdivision units, and  FIG. 7  illustrates a procedure of inserting image subdivision units into vertically shifted image subdivision units. 
         [0035]    Hereinafter, the apparatus  300  for correcting image distortion of a lens according to an embodiment of the present invention will be described with reference to  FIGS. 3 to 7 . 
         [0036]    The input unit  310  may generate or receive image information ( 410  of  FIG. 4A, 501  of  FIG. 5 ). The input unit  310  may be a device or mechanism such as a camera or CCTV which is capable of capturing images, but embodiments of the present invention are not limited thereto. The image information  410 ,  501  is information captured by the input unit  310 . For example, the image information  410 ,  501  may be a photograph or a moving image. 
         [0037]    The segmentation unit  320  may segment the image information  501  (see  FIG. 5 ) into one or more image subdivision units  510  to  519  and  520  to  529  (see  FIG. 5 ). The image subdivision units  510  to  519  and  520  to  529  are units for dividing the image information  501  into parts having a certain size. For example, the image subdivision units  510  to  519  and  520  to  529  may be pixels. Dividing the image information  501  into one or more image subdivision units  510  to  519  and  520  to  529  is intended to individually shift the image subdivision units  510  to  519  and  520  to  529 . 
         [0038]    The setting unit  330  may set the center ( 421  of  FIG. 4B, 502  of  FIG. 5 ) of the image information ( 420  of  FIG. 4B, 501  of  FIG. 5 ). The setting unit  330  may set the center to the image subdivision unit  502 , which is the center of both horizontal and vertical arrangements. 
         [0039]    Alternatively, the setting unit  330  may set the center to an image subdivision unit in the most severely distorted portion of the image information. 
         [0040]    The setting unit  330  may set the center to a boundary between image subdivision units, but embodiments of the present invention are not limited thereto. 
         [0041]    The controller  340  may shift one or more image subdivision units  510  to  519  and  520  to  529  by variation ratios  610 ,  620 ,  710  and  720  with respect to the image subdivision unit  502  of the image information  501 . 
         [0042]    In one embodiment, the controller  340  may horizontally or vertically shift the image subdivision units  510  to  519  and  520  to  529 . The controller  340  may diagonally shift the image subdivision units. The directions in which the controller  340  shifts the image subdivision units are not limited to the horizontal direction, vertical direction and diagonal direction. 
         [0043]    A pixel value may represent the color of each of the image subdivision units  510  to  519  and  520  to  529 . For example, the pixel value may be an RGB value, YCbCr value, HSB value or CMY value. For example, in  FIG. 5 , the pixel values of the image subdivision units  502  and  515  may be  50  and  60 . The variation ratios  610 ,  620 ,  710  and  720  may be distances between the shifted image subdivision units. 
         [0044]    The variation ratios  610 ,  620 ,  710  and  720  may be differently set for the respective image subdivision units  510  to  519  and  520  to  529 . 
         [0045]    For example, as shown in  FIGS. 6 and 7 , the variation ratios  610 ,  620 ,  710  and  720  may increase as the distance from the image subdivision unit  502  of the image information  501  increases. That is, a higher variation ratio may be applied to an image subdivision unit which is spaced farther from the image subdivision unit  502  of the image information  501 . 
         [0046]    Alternatively, although not shown in the figures, the variation ratio may decrease as the distance from the image subdivision unit  502  of the image information  501  increases. That is, a lower variation ratio may be applied to an image subdivision unit which is spaced farther from the image subdivision unit  502  of the image information  501 . 
         [0047]    Alternatively, the same variation ratio may be applied to the image subdivision units disposed in a partial region of the image information  501 . 
         [0048]    Alternatively, the variation ratio may be designated by the user. 
         [0049]    Interpolation spaces  630 ,  640 ,  730  and  740  are generated between the shifted image subdivision units, and the interpolation unit  350  may insert one or more image subdivision units corresponding to the shifted image subdivision units in the interpolation spaces  630 ,  640 ,  730  and  740 . 
         [0050]    Referring to  FIGS. 4 to 6 , the controller  340  horizontally shifts the image subdivision units  510  to  519 , and the interpolation unit  350  inserts image subdivision units  531 ,  532  and  533  into the shifted image subdivision units  515 ,  516  and  517 . Hereinafter, this procedure will be described in detail. 
         [0051]    First, the controller  340  shifts the image subdivision unit  515  to the position of the image subdivision unit  516  with respect to the image subdivision unit  502 . The image subdivision unit  516  is shifted to the position of the image subdivision unit  519 . In this way, the image subdivision units  510  to  519  are shifted. According to the embodiment illustrated in  FIG. 6 , as the distance between the center  502  and the image subdivision units  510  to  519  increases, the variation ratio  610 ,  620  by which the image subdivision units  510  to  519  are shifted increases. 
         [0052]    In contrast with the embodiment of  FIG. 6 , the controller  340  may shift the image subdivision units  510  to  519  by the same variation ratio. Alternatively, as the distance between the center and the image subdivision units  510  to  519  increases, the variation ratio by which the image subdivision units  510  to  519  are shifted may decrease. 
         [0053]    The controller  340  may shift the image subdivision unit  515  to a position between the image subdivision unit  515  and the image subdivision unit  516 . In this case, the image subdivision unit  515  may be regenerated at the position of the image subdivision unit  516 . 
         [0054]    When the image subdivision units  515 ,  516  and  517  are shifted, the interpolation spaces  630  and  640  are generated. The interpolation spaces  630  and  640  refer to spaces where no image subdivision unit is present after the image subdivision units are shifted. 
         [0055]    In  FIG. 6 , the empty spaces generated according to shift of the image subdivision units  515 ,  516  and  517  are the interpolation spaces  630  and  640 . The interpolation unit  350  inserts the image subdivision units  531 ,  532  and  533  into the interpolation spaces  630  and  640 . 
         [0056]    In  FIG. 6 , the interpolation unit  350  may insert an image subdivision unit  531  having  55  as a pixel value into the interpolation space  630  and the image subdivision units  532  and  533  having  63  and  66  as pixel values into the interpolation space  640 . The inserted image subdivision units  531 ,  532  and  533  have pixel values corresponding to the shifted image subdivision units  515 ,  516  and  517 . For example, in  FIG. 6 , the pixel values of the image subdivision units  532  and  533  may be within the pixel values of the image subdivision unit  515  and image subdivision unit  516 . By inserting image subdivision units having pixel values corresponding to the pixel values of the shifted the image subdivision units, high-definition image information may be corrected, and image quality may be improved. 
         [0057]    Meanwhile, the controller  340  may remove image subdivision units which cannot be shifted to the positions of other image subdivision units. In  FIG. 4B , the controller may remove the image subdivision units in the areas  422  and  423 . In  FIG. 6 , since the image subdivision unit  517  cannot be shifted to the position of another image subdivision unit, the controller  340  may remove the image subdivision unit  517 . 
         [0058]    Referring to  FIGS. 4 to 7 , the controller  340  vertically shifts the image subdivision units  520  to  529 , and the interpolation unit  350  inserts image subdivision units  541 ,  542  and  543  into the spaces between the shifted image subdivision units  515 ,  516  and  517 . Hereinafter, this procedure will be described in detail. 
         [0059]    First, the controller  340  shifts the image subdivision unit  524  to the position of the image subdivision unit  523  with respect to the image subdivision unit  502 . The image subdivision unit  523  is shifted to the position of the image subdivision unit  520 . In this way, the image subdivision units  520  to  529  are shifted. According to the embodiment illustrated in  FIG. 7 , as the distance from the center  502  increases, the variation ratio  710 ,  720  increases. In contrast with the embodiment of  FIG. 7 , the controller  340  may shift the image subdivision units  520  to  529  by the same variation ratio. Alternatively, as the distance from the center increases, the variation ratio by which the image subdivision units  520  to  529  are shifted may decrease. 
         [0060]    The controller  340  may shift the image subdivision unit  524  to a position between the image subdivision unit  524  and the image subdivision unit  523 . In this case, the image subdivision unit  524  may be regenerated at the position of the image subdivision unit  523 . 
         [0061]    When the image subdivision units  522 ,  523  and  524  are shifted, interpolation spaces  730  and  740  are generated. In  FIG. 7 , the empty spaces generated according to shift of the image subdivision units  522 ,  523  and  524  are the interpolation spaces  730  and  740 . The interpolation unit  350  inserts the image subdivision units  541 ,  542  and  543  into the interpolation spaces  730  and  740 . 
         [0062]    In  FIG. 7 , the interpolation unit  350  may insert an image subdivision unit  541  having  45  as a pixel value into the interpolation space  730  and the image subdivision units  543  and  542  having  33  and  36  as pixel values into the interpolation space  740 . The inserted image subdivision units  541 ,  542  and  543  have pixel values corresponding to the shifted image subdivision units  522 ,  523  and  524 . For example, in  FIG. 7 , the pixel values of the image subdivision units  542  and  543  may be within the pixel values of the image subdivision unit  523  and  524 . By inserting image subdivision units having pixel values corresponding to the pixel values of the shifted the image subdivision units, high-definition image information may be corrected, and image quality may be improved. 
         [0063]    Meanwhile, the controller  340  may remove image subdivision units which cannot be shifted to the positions of other image subdivision units. In  FIG. 4B , the controller may remove the image subdivision units in the areas  422  and  423 . In  FIG. 7 , since the image subdivision units  522  cannot be shifted to the position of another image subdivision unit, the controller  340  may remove the image subdivision units  522 . 
         [0064]    The output unit  360  may output corrected image information. The output unit  360  is a device capable of outputting image information. For example, the output unit  360  may be a display, a monitor, or a TV. Referring to  FIG. 4C , the output unit may output the image information  430  after correction. 
         [0065]      FIG. 8  illustrates a procedure of correcting a distorted image in an apparatus for correcting image distortion of a lens according to another embodiment of the present invention. Hereinafter, a description will be given of an apparatus for correcting image distortion of a lens according to another embodiment of the present invention, with reference to  FIG. 8 . 
         [0066]    According to another embodiment, an apparatus for correcting image distortion of a lens may include an input unit, a setting unit, a segmentation unit, a controller, and output unit, and an interpolation unit. The input unit, output unit and interpolation unit of the apparatus for correcting image distortion according to this embodiment have the same configurations, functions and effects as the input unit, output unit and interpolation unit described in  FIGS. 3 to 7 , and thus a description thereof is omitted. 
         [0067]    The setting unit may set the center  810  of image information, and the segmentation unit may segment the image information into predetermined units based on the center  810 . The method used by the setting unit to set the center  810  of the image information is the same as the method described in  FIGS. 3 to 7 , and thus a description thereof is omitted. 
         [0068]    The predetermined units may be quadrisections arranged in the horizontal and vertical directions with respect to the center  810  of the image information. However, this is simply an example, and the predetermined units may be designated differently from the quadrisections by the user. 
         [0069]    In order to correct the image information according to the degree of distortion, the segmentation unit segments the image information into predetermined units, thereby obtaining image information segments  820 ,  830 ,  840  and  850 . That is, the image information is corrected by dividing the image information segments  820 ,  830 ,  840  and  850  into a part which is subjected to severe distortion and a part which is not subjected to severe distortion. Thereby, correction efficiency may be denounced. 
         [0070]    According to an embodiment, the setting unit may set centers  821 ,  831 ,  841  and  851  of the image information segments  820 ,  830 ,  840  and  850  divided into predetermined units. The segmentation unit may segment each of the image information segments  820 ,  830 ,  840  and  850  into one or more image subdivision units. 
         [0071]    The method used by the setting unit to set the centers  821 ,  831 ,  841  and  851  of the image information segments  820 ,  830 ,  840  and  850  is the same as the method illustrated in  FIGS. 3 to 7 , and thus a description thereof is omitted. The method used by the segmentation unit to segment the image information segments  820 ,  830 ,  840  and  850  is the same as the method illustrated in  FIGS. 3 to 7 , and thus a description thereof is also omitted. 
         [0072]    The controller may correct distortion of each of the image information segments  820 ,  830 ,  840  and  850  divided into predetermined units. In one embodiment, the controller may shift one or more image subdivision units of each of the image information segments  820 ,  830 ,  840  and  850  by a corresponding variation ratio with respect to the centers  821 ,  831 ,  841  and  851 . The method used by the controller to shift the image subdivision units of each of the image information segments  820 ,  830 ,  840  and  850  by a corresponding variation ratio with respect to the centers  821 ,  831 ,  841  and  851  is the same as the method illustrated in  FIGS. 3 to 7 , and thus a description thereof is omitted. 
         [0073]    According to another embodiment of the present invention illustrated in  FIG. 8 , the setting unit may set the centers  821 ,  831 ,  841  and  851  of the image information segments  820 ,  830 ,  840  and  850  to the center  810 . If the centers  821 ,  831 ,  841  and  851  of the predetermined units  820 ,  830 ,  840  and  850  are set to the center  810  of the image information, the predetermined units may be quadrisected in the horizontal and vertical directions to correct distortion. In addition, if the centers  821 ,  831 ,  841  and  851  of the predetermined units  820 ,  830 ,  840  and  850  are set to the center  810  of the image information, the image information may be quadrisected in the horizontal and vertical directions, and distortion of each of the quadrisections may be corrected. 
         [0074]    Those skilled in the art will appreciate that various substitutions, modifications, variations can be made to the present invention without departing from the technical spirit of the invention and that the present invention is not limited to the embodiments described above and the accompanying drawings.