Abstract:
A target searching device has an image capture unit that captures and outputs a captured image having I×J pixels, an image display unit that displays a displayed image having M×N pixels, and an image process unit that is coupled with the image capture unit and the image display unit. The target searching device can perform a method of displaying an image, which includes the steps of acquiring a captured image having I×J pixels, selecting a pre-set target from the captured image, dividing the captured image into a plurality of image blocks with reference to the pre-set target, resealing each image block by a set of zoom parameters to transform the captured image of I×J pixels into a displayed image having M×N pixels, and displaying the displayed image.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a target searching device, and in particular, to a target searching device and an image display method which can enhance the target part of the image. 
         [0003]    2. Description of the Prior Art 
         [0004]    Target searching devices are assistive devices used by users to search for viewing a target or aiming at a target. For example, a telescope is usually used to search for and view distant objects. Similarly, the sight on a weapon is used to assist shooters to search for and aim at desired targets for shooting. 
         [0005]    A conventional electronic telescope or sight is equipped with an image capture unit to capture the target image, and an image display unit to display the image captured. The pixels of the image displayed in the image display unit are usually less than that of the image captured in the image capture unit. Consequently, when the image captured in the image capture unit is displayed in the image display unit, the image has to be reduced by a predefined factor in order to be fully displayed in the image display unit. However, displaying the reduced image will render the image smaller and thereby make it more difficult to search. Also, if the image captured is not reduced, only part of the image captured can be displayed, and the search of a target can be rendered equally difficult. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    It is an object of the present invention is to provide a target searching device and a display method which can selectively enhance the target part of an image to facilitate the search of the target in the image. 
         [0007]    In order to accomplish the objects of the present invention, the present invention provides a method of displaying an image, which includes the steps of acquiring a captured image having I×J pixels, selecting a pre-set target from the captured image, dividing the captured image into a plurality of image blocks with reference to the pre-set target, resealing each image block by a set of zoom parameters to transform the captured image of I×J pixels into a displayed image having M×N pixels, and displaying the displayed image. 
         [0008]    The present invention also provides a target searching device that has an image capture unit that captures and outputs a captured image having I×J pixels, an image display unit that displays a displayed image having M×N pixels, and an image process unit that is coupled with the image capture unit and the image display unit. The image process unit receives the captured image from the image capture unit, selects a pre-set target from the captured image, and divides the captured image into a plurality of image blocks with reference to the pre-set target. The image process unit then rescales each image block with reference to a set of zoom parameters to transform the captured image of I×J pixels into the displayed image of M×N pixels, which can be displayed by the image display unit. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic block diagram of one embodiment of a target searching device according to the present invention. 
           [0010]      FIG. 2  is a flow chart of one embodiment of the image display method of a target searching device according to the present invention. 
           [0011]      FIG. 3  is an example of the output image of the image capture unit in  FIG. 1 . 
           [0012]      FIG. 4  is a scaled down image in proportion to the image in  FIG. 3 . 
           [0013]      FIG. 5  is a transformation of the image in  FIG. 3  by the image process unit in  FIG. 1 . 
           [0014]      FIG. 6  is an example of another output image of the image capture unit in  FIG. 1 . 
           [0015]      FIG. 7  is a scaled down image in proportion to the image in  FIG. 6 . 
           [0016]      FIG. 8  is a transformation of the image in  FIG. 6  by the image process unit in  FIG. 1 . 
           [0017]      FIG. 9  illustrates the image transformed from the image in  FIG. 3  by a polar coordinate. 
           [0018]      FIG. 10  illustrates the image transformed from the image in  FIG. 6  by a polar coordinate. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims. 
         [0020]    Referring to  FIG. 1 , a target searching device  100  according to one embodiment of the present invention includes an image capture unit  110 , an image process unit  120 , an image display unit  130 , and an eyeball tracking unit  140 , with the image process unit  120  coupled with the image capture unit  110 , the image display unit  130 , and the eyeball tracking unit  140 , respectively. The eyeball tracking unit  140  is optional and can be omitted if the selection of the pre-set target does not refer to the output of the eyeball tracking unit  140 . 
         [0021]    The image capture unit  110  can be an image sensor, such as Charge Coupled Device (CCD) or Complementary Metal Oxide Semiconductor (CMOS), for capturing distant target images and outputting an image having I×J pixels. 
         [0022]    In the present embodiment, the output image  310  ( FIG. 3 ) or  610  ( FIG. 6 ) from the image capture unit  110  can have 1280×960 pixels, for example. However, the image which can be displayed by the image display unit  130  has only 640×480 pixels. Consequently, it is necessary to scale down the image of the 1280×960 pixels in proportion by a factor of 4 into that of 640×480 pixels, so that the image  310  ( FIG. 3 ) or the image  610  ( FIG. 6 ) can be fully displayed as image  410  ( FIG. 4 ) or image  710  ( FIG. 7 ), respectively. However, this will significantly decrease the size of the pre-set targets of the images  410  and  710 , and thereby adversely affect the search of targets. 
         [0023]    Consequently, the target searching device  100  in  FIG. 1  uses the image display method shown in  FIG. 2  to transform the image  310  or  610  having 1280×960 pixels into the image of  510  ( FIG. 5 ) or  810  ( FIG. 8 ) having 640×480 pixels, respectively. The transformation of the image display method is described in details as follows. 
         [0024]    First, in step S 210 , the image capture unit  110  captures a distant image  310  or  610 . In step S 220 , the image process unit  120  receives the image  310  or  610  from the image capture unit  110 , and selects a pre-set target  319  or  619  in the image  310  or  610  according to the user&#39;s decision. The pre-set target  319  or  619  can also be determined in step S 230 , in which the position of the user&#39;s eyeball is detected by the eyeball tracking unit  140 . The pre-set target  319  or  619  selected by the user is assumed here to be at the center of the image  310  or  610 . 
         [0025]    Next, in step S 240 , the selected pre-set target  319  or  619  is taken as the center to divide the image  310  or  610  into multiple image blocks. In the present embodiment, for example, the image  310  or  610  is drawn with vertical lines  311 ,  312 ,  313 ,  314 ,  315  and  316 , or  611 ,  612 ,  613 ,  614 ,  615  and  616 , on both sides of the pre-set target  319  or  619 , respectively, and horizontal lines  321 ,  322 ,  323 ,  324 ,  325  and  326 , or  621 ,  622 ,  623 ,  624 ,  625  and  626  on the both sides of the pre-set target  319  or  619 , respectively, to form multiple rectangular image blocks. 
         [0026]    Next, in step S 250 , each image block is magnified or reduced by a set of zoom parameters to transform the image of I×J pixels into that of M×N pixels. As an example, take the transformation of the image  310  or  610  (which have 1280×960 pixels) into that of image  510  or  810  (which have 640×480 pixels). The positions of the vertical lines  311  and  312  are located by extending 134 pixels leftward and rightward from the pre-set target  319  of the image  310 . Similarly, the positions of the vertical lines  611  and  612  are located by extending 134 pixels leftward and rightward from the pre-set target  619  of the image  610 . In a similar manner, the positions of the vertical lines  313  and  314  (or  613  and  614 ) are located by extending 240 pixels leftward and rightward from vertical lines  311  and  312  (or  611  and  612 ). In addition, the positions of the vertical lines  315  and  316  (or  615  and  616 ) are located by extending 96 pixels leftward and rightward from the vertical lines  313  and  314  (or  613  and  614 ). 
         [0027]    The horizontal lines are adjusted in a similar manner. For example, the positions of the horizontal lines  321  and  322  (or  621  and  622 ) are located by extending 100 pixels from the pre-set target  319  (or  619 ) of the image  310  (or  610 ) upward and downward. The positions of the horizontal lines  323  and  324  (or  623  and  624 ) are located by extending 180 pixels upward and downward from the horizontal lines  321  and  322  (or  621  and  622 ). The positions of the horizontal lines  325  and  326  (or  625  and  626 ) are located by extending 75 pixels upward and downward from the horizontal lines  323  and  324  (or  623  and  624 ). 
         [0028]    Consequently, the image  310  is divided into 49 rectangular image blocks by the vertical lines  311 ,  312 ,  313 ,  314 ,  315 ,  316 , the horizontal lines  321 ,  322 ,  323 ,  324 ,  325 ,  326  and the boundaries of the image  310 . Similarly, the image  610  is divided into 49 rectangular image blocks by the vertical lines  611 ,  612 ,  613 ,  614 ,  615 ,  616 , the horizontal lines  621 ,  622 ,  623 ,  624 ,  625 ,  626 , and the boundaries of the image  610 . The rectangular image blocks are magnified or reduced by a zoom parameter along the transverse axis and a zoom parameter along the longitudinal axis such that the image  510  or  810  is transformed and becomes an image of 640×480 pixels, in the manner described below. 
         [0029]    The rectangular image blocks bordered by the vertical lines  311 ,  312  and the horizontal lines  321  and  322  (or the vertical lines  611 ,  612  and the horizontal lines  621  and  622 ) contain the pre-set target of the image  319  (or  619 ). To maintain the clarity of the present image blocks, the zoom factor of the zoom parameter for the present image block can be set to be 1 along both the transverse and longitudinal axes. Consequently, the zoom factor of the zoom parameter is 1 for the rectangular image block bordered by the vertical lines  311 ,  312  (or  611 ,  612 ) along the transverse axis, and the zoom factor of the zoom parameter is 1 for the rectangular image block bordered by the horizontal lines  321 ,  322  (or  621 ,  622 ) along the longitudinal axis. 
         [0030]    Moreover, the zoom factor of the zoom parameter along the transverse axis can be half (i.e., ½) for the rectangular image blocks bordered by the vertical lines  311  and  313 , and for the image blocks bordered by the vertical lines  312  and  314 . Similarly, the zoom factor of the zoom parameter along the transverse axis can be half (i.e., ½) for the rectangular image blocks bordered by the vertical lines  611  and  613 , and for the image blocks bordered by the vertical lines  612  and  614 . 
         [0031]    The zoom factor of the zoom parameter along the transverse axis can be one-third (i.e., ⅓) for the rectangular image blocks bordered by the vertical lines  313  and  315  (or  613  and  615 ), and for the image blocks bordered by the vertical lines  314  and  316  (or  614  and  616 ). 
         [0032]    The zoom factor of the zoom parameter along the transverse axis can be ⅕ for the rectangular image blocks bordered by the vertical line  315  and the boundary (or the vertical line  615  and the boundary in  FIG. 6 ), and for the image blocks bordered by the vertical line  316  and the boundary (or the vertical line  616  and the boundary in  FIG. 6 ). 
         [0033]    Furthermore, the zoom factor of the zoom parameter along the longitudinal axis can be half (i.e., ½) for the rectangular image blocks bordered by the horizontal lines  321  and  323  (or the horizontal lines  621  and  623 ), and for the image blocks bordered by the horizontal lines  322  and  324  (or the horizontal lines  622  and  624 ). 
         [0034]    The zoom factor of the zoom parameter along the longitudinal axis can be one third (i.e., ⅓) for the rectangular image blocks bordered by the horizontal lines  323  and  325  (or the horizontal lines  623  and  625 ), and for the image blocks bordered by the horizontal lines  324  and  326  (or the horizontal lines  624  and  626 ). Also, the zoom factor of the zoom parameter along the longitudinal axis can be ⅕ for the rectangular image blocks bordered by the horizontal line  325  and the boundary of  FIG. 3  (or the horizontal line  625  and the boundary of  FIG. 6 ), and for the image blocks bordered by the horizontal line  326  and the boundary of  FIG. 3  (or the horizontal line  626  and the boundary of  FIG. 6 ). 
         [0035]    Various operations of image processing can be used to magnify or reduce images. Different operations will result in different effects of image transformation. According to one non-limiting embodiment of the present invention, a simple pixel-removal operation is used to achieve the image reduction. For example, to reduce the image along the transverse or longitudinal axis to half, one out of every two pixels along the transverse or longitudinal axis is removed. Similarly, to reduce the image along the transverse or longitudinal axis to one-third, two out of every three pixels along the transverse or longitudinal axis are removed. Also, to reduce the image along the transverse or longitudinal axis to ⅕, for example, four out of every five pixels along the transverse or longitudinal axis are removed. 
         [0036]    Finally, in step S 260 , the display image  510  or  810  after transformation is output and displayed in the image display unit  130  so that the image  310  or  610  output from the image capture unit  110  can be fully displayed. Although some distortion will occur in the images  510  or  810  after transformation, the rectangular image block containing the pre-set target  319  or  619  has been enhanced along with the full display of the image captured. Consequently, the user can easily change the location of the pre-set target  319  or  619  and find the desired target. The search for a target is therefore not affected by the reduction of the pre-set target  319  or  619 , or an incomplete image. 
         [0037]    The embodiment described above divides the image  310  or  610  into  49  rectangular image blocks, and reduces the image blocks by a factor of 1, half (½), one-third (⅓), and ⅕, respectively, from the center along the transverse and longitudinal axes to achieve the image transformation. It is also possible to increase the number of the divisions of the image blocks and to apply a gradual change of the zoom parameter for the transformation of the displayed image such that the distortion of image can be reduced. Also, the number of the division of the image blocks and the zoom parameter can also be set according to the requirements of different display images to render the image after transformation more consistent to the user&#39;s actual demands. For example, applying the factors of 1, ⅘, ⅗, ⅖ and ⅕ (in this sequential order) from the center of the image will provide a smoother zoom parameter for the transformation of the displayed image, and will reduce the distortion of the image. 
         [0038]    Furthermore, to clearly display the pre-set target  319  or  619 , the zoom factor can be set to be larger than 1 for the innermost image block(s) containing the pre-set target  319  or  619 , while further reducing the other image blocks to achieve the same transformation of image pixels. This practice will further enhance the image of the pre-set target  319  or  619 . 
         [0039]    While the division and magnification or reduction of the image  310  or  610  can be achieved by using the transverse and longitudinal axes of the rectangular coordinate as the reference axes, other approaches are also possible. For example, polar coordinates can be used to divide the image  310  or  610  into a plurality of non-rectangular image blocks. A different set of zoom parameters along different coordinate axes will be applied for each non-rectangular image block for magnification or reduction. An image of I×J pixels can also be transformed into an image of M×N pixels. 
         [0040]    In  FIGS. 9 and 10 , a plurality of radiating lines are drawn by taking the pre-set target  319  or  619  of the image  310  or  610 , respectively, as the center, and then a plurality of concentric ovals are drawn to encircle the pre-set target  319  or  619  such that a plurality of fan-shaped image blocks are formed. Each fan-shaped image block is applied with a set of zoom parameters for magnification or reduction to transform the image  310  or  610  of 1280×960 pixels into the image  910  or  1010  of 640×480 pixels. To maintain the image clarity of the image around the pre-set target  319  or  619 , the zoom factor of the zoom parameter can be set to be two (2) along different axes for the image blocks in the innermost oval enclosing the pre-set target  319  or  619 . The zoom factor of the zoom parameter for the other image blocks can be gradually reduced away from the pre-set target  319  or  619  such that the number of pixels of the image  910  or  1010  after transformation decreases gradually away from the center. 
         [0041]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.