Abstract:
Proposed is a method of detecting a moving object, including: providing an image-set at least including a first image and a second image correlated in a time series, the first image preceding the second image; defining a detecting region and a detecting direction so as to construct a virtual gate in the first image; estimating the motion vector in a time series; comparing, by the virtual gate, the second image with the first image so as to determine a difference therebetween in terms of an object&#39;s position and motion vector; and retrieving the object to be an effective moving object upon determination of the object as lying within the detecting region defined in the virtual gate and moving in a direction substantively the same with the detecting direction. This invention presents a moving object detection method without the need to construct a background model a priori.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to methods of detecting a moving object, and more particularly, to a method of detecting a moving object for use in an image monitoring system. 
         [0003]    2. Description of the Prior Art 
         [0004]    It is an important and yet insurmountable issue in daily life to concurrently detect and count moving objects in images with a complicated background. There are various commercially available motion-image monitoring system, but the systems fail to address the aforesaid issue. 
         [0005]    For instance, both U.S. Pat. No. 6,954,226 and U.S. Pat. No. 5,748,775 disclose a detection method that involves detecting moving objects in images by background subtraction, but the detection method is unfit for an overly intricate background inevitably dogged by errors in whatever signals detected. Furthermore, the detection method disclosed in U.S. Pat. No. 6,954,226 entails acquiring information values by comparing a captured real-time monitored image with a standard image, and determining whether the information values are greater than a predetermined threshold value, wherein the information values greater than the threshold value indicate an object in the real-time image is in motion. However, the detection method cannot detect the direction in which an object moves. 
         [0006]    The prior art can neither discern and count moving objects in an intricate background nor adjust flexibly a direction for detection and a range of retrieval in order to meet user needs. As a result, the prior art lacks ease of use and is flawed by inefficient monitoring. In view of this, the drawbacks of the prior art call for an immediate solution. 
       SUMMARY OF THE INVENTION 
       [0007]    In light of the aforesaid drawbacks of the prior art, the present invention provides a method of detecting a moving object, comprising the steps of: providing an image-set at least comprising a first image and a second image correlated in a time series, the first image preceding the second image; defining a detecting area in an appropriate region of the first image; moving the detecting area so as to form a motion vector; combining the detecting area with the motion vector so as to construct a virtual gate defined with a detecting region and a detecting direction; and comparing, by the virtual gate, the second image with the first image so as to determine a difference therebetween in terms of an object&#39;s position, and retrieving the object as an effective moving object upon determination of the object as lying within the detecting region defined in the virtual gate and moving in a direction substantively equal to the user-defined detecting direction. This invention presents a virtual gate method for the moving object detection without the need to construct a background model a priori. The present invention utilizes motion vector analysis which detects moving objects passing through the gate along any desired direction. This method is particularly applicable to complex situations. 
         [0008]    The present invention further provides a method of detecting a moving object, comprising the steps of: providing an image-set at least comprising a first image group and a second image group (equivalent to a first video and a second video) correlated in a time series, the first image group, which comprises a plurality of first images, preceding the second image group, which comprises a plurality of second images; defining a detecting area in an appropriate region of the images of the first image group; moving the detecting area so as to form a motion vector; combining the detecting area with the motion vector so as to construct a virtual gate defined with a detecting region and a detecting direction; and comparing, by the virtual gate, the second images of the second image group so as to determine a difference therebetween in terms of an object&#39;s position, and retrieving the object as an effective moving object upon determination of the object as lying within the detecting region defined in the virtual gate and moving in a direction substantively equal to the user-defined detecting direction. 
         [0009]    The present invention further provides a method of detecting a moving object, comprising the steps of: providing an image-set at least comprising a first image and a second image correlated in a time series, the first image preceding the second image; defining a detecting area in an appropriate region of the first image; moving the detecting area so as to form a motion vector; combining the detecting area with the motion vector so as to construct a virtual gate defined with a detecting region and a detecting direction; defining an image picking area in the first image; and comparing the second image with the first image so as to determine a difference therebetween in terms of an object&#39;s position, and retrieving the object as an effective moving object upon determination of the object as appearing in the image picking area, lying within the detecting region defined in the virtual gate, and moving in a direction substantively equal to the detecting direction. 
         [0010]    It is a primary objective of the present invention to provide a method of detecting a moving object so as to detect a moving object in an intricate background/environment. 
         [0011]    Another objective of the present invention is to provide a method of detecting a moving object without the need to construct a background model a priori. 
         [0012]    Another objective of the present invention is to provide a method of detecting a moving object so as to detect and count moving objects in an intricate background/environment. 
         [0013]    Yet another objective of the present invention is to provide a method of detecting a moving object, wherein an area to be detected can be freely adjusted according to user&#39;s needs. 
         [0014]    A further objective of the present invention is to provide a method of detecting a moving object, wherein the method allows a specific direction to be flexibly selected to meet user needs with a view to detecting an object moving in the specific direction. 
         [0015]    A further objective of the present invention is to provide a method of detecting a moving object, wherein the method is adapted for use in an existing monitoring system so as to monitor and count moving objects with a cost-efficient budget. 
         [0016]    A further objective of the present invention is to provide a method of detecting a moving object, wherein the method is adapted for use in a security and surveillance system so as to provide entry/exit control management, for example. 
         [0017]    A further objective of the present invention is to provide a method of detecting a moving object, wherein the method is adapted for use in commercial research in order to record market analysis data, such as a visitor rate. 
         [0018]    A further objective of the present invention is to provide a method of detecting a moving object, wherein the method is adapted for use in ecological research in order to record ecological features and lives of a variety of creatures. 
         [0019]    A further objective of the present invention is to provide a method of detecting a moving object with ease of use and convenience in monitoring and management. 
         [0020]    A further objective of the present invention is to provide a method of detecting a moving object, wherein a plurality of virtual gates can be defined and a plurality of specific directions can be selected flexibly to meet user needs with a view to detecting a plurality of objects moving in the specific directions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1A  is a flowchart of a method of detecting a moving object according to a first preferred embodiment of the present invention; 
           [0022]      FIG. 1B  is a partial schematic view of the first preferred embodiment of the present invention; 
           [0023]      FIG. 1C  is another partial schematic view of the first preferred embodiment of the present invention; 
           [0024]      FIG. 1D  is yet another partial schematic view of the first preferred embodiment of the present invention; 
           [0025]      FIG. 2A  is a flowchart of a method of detecting a moving object according to a second preferred embodiment of the present invention; 
           [0026]      FIG. 2B  is a partial schematic view of the second preferred embodiment of the present invention; 
           [0027]      FIG. 2C  is another partial schematic view of the second preferred embodiment of the present invention; 
           [0028]      FIG. 3A  is a flowchart of a method of detecting a moving object according to a third preferred embodiment of the present invention; 
           [0029]      FIG. 3B  is a partial schematic view of the third preferred embodiment of the present invention; and 
           [0030]      FIG. 3C  is another partial schematic view of the third preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0031]    The present invention discloses a method of detecting a moving object, and employs general concepts of monitoring system and logic operation that are comprehensible to persons ordinarily skilled in the art and therefore are not described in detail hereunder for the sake of brevity. The appended drawings are schematic views which purport to show the features of the present invention and therefore do not, and need not, illustrate the present invention in a complete and comprehensive manner. 
         [0032]    Referring to  FIG. 1A , which is a flowchart of a method of detecting a moving object according to a first preferred embodiment of the present invention, the method comprises the following steps. 
         [0033]    At step  10 , an image-set  101  (for example, images taken by a surveillance camera) is provided. The image-set  101  at least comprises a first image  101   a  and a second image  101   b  correlated in a time series. The first image  101   a  precedes the second image  101   b . The first image  101   a  and the second image  101   b  can be images of pedestrians, vehicles, animals, or any visible moving objects. 
         [0034]    Referring to  FIG. 1A  and  FIG. 1B , at step  11 , a detecting area  111  is defined in an appropriate region of the first image  101   a . The detecting area  111  is rectangular or is of any shape adjustable when necessary. The measurement unit of the detecting area  111  is an image block. The image block is of dimensions 8 pixels×8 pixels or is of any dimensions adjustable when necessary. 
         [0035]    Referring to  FIG. 1A  and  FIG. 1B , at step  12 , the detecting area  111  is moved in a specific direction  121 , so as to form a motion vector  122 . 
         [0036]    Referring to  FIG. 1A ,  FIG. 1B  and  FIG. 1C , at step  13 , the detecting area  111  is combined with the motion vector  122  so as to construct a virtual gate  131 . Referring to  FIG. 1C , the virtual gate  131  constructed is defined with a detecting region  132  and a detecting direction  133 . The detecting direction  133  can be configured flexibly to meet user needs, though the configured detecting direction  133  must be unidirectional and invariable. The motion vector  122  comprises a motion angle and a motion distance, both of which are user-defined. The unit of the motion distance is pixel. 
         [0037]    Referring to  FIG. 1A , and  FIG. 1C , at step  14 , with the virtual gate  131 , the second image  101   b  is compared with the first image  101   a  so as to determine a difference therebetween in terms of an object&#39;s position, and the object is retrieved as an effective moving object upon determination of the object as lying within the detecting region  132  defined in the virtual gate  131  and moving in a direction substantively the same with the detecting direction  133 . “Substantively the same with” means the difference between the direction in which the object moves and the detecting direction  133  defined in the virtual gate  131  falls within a predetermined range. 
         [0038]    Referring now to  FIG. 1D , with the method of detecting a moving object of the present invention, not only is motion of a single object detected, but motion of a plurality of objects can be detected concurrently. More particularly, a second detecting region  134  and a second detecting direction  135  can be defined in the same first image  101   a , so as to construct a second virtual gate  136  with a view to detect a second moving object, using the same method of detecting a moving object described above. Particularly, the direction can be different from the detecting direction  133  defined in the virtual gate  131 . The method is not repeated herein. 
         [0039]    Referring to  FIG. 2A , which is a flowchart of a method of detecting a moving object according to a second preferred embodiment of the present invention, the method comprises the following steps. 
         [0040]    At step  20 , an image-set  201  (for example, images taken by a surveillance camera) is provided. The image-set  201  at least comprises a first image group  201   a  and a second image group  201   b  correlated in a time series, wherein the first image group  201   a  precedes the second image group  201   b . The first image group  201   a  comprises a plurality of first images  201   c , and the second image group  201   b  comprises a plurality of second images  201   d , wherein the images are those of pedestrians, vehicles, animals, or any visible moving objects. 
         [0041]    Referring to  FIG. 2A  and  FIG. 2B , at step  21 , a detecting area  211  is defined in an appropriate region of the first image group  201   a . The detecting area  211  is rectangular or is of any shape adjustable when necessary. The measurement unit of the detecting area  211  is an image block. The image block is preferably of dimensions 8 pixels×8 pixels, or is of any dimensions adjustable when necessary. 
         [0042]    Referring to  FIG. 2A  and  FIG. 2B , at step  22 , the detecting area  211  is moved in a specific direction  221 , so as to form a motion vector  222 . 
         [0043]    Referring to  FIG. 2A ,  FIG. 2B , and  FIG. 2C , at step  23 , the detecting area  211  is combined with the motion vector  222  so as to construct a virtual gate  231 . Referring to  FIG. 2C , the virtual gate  231  constructed is defined with a detecting region  232  and a detecting direction  233 . The detecting direction  233  is configured flexibly to meet user needs, though the configured detecting direction  233  must be unidirectional and invariable. The motion vector  222  comprises a motion angle and a motion distance, both of which are user-defined. The unit of the motion distance is pixel. 
         [0044]    Referring to  FIG. 2A  and  FIG. 2C , at step  24 , with the virtual gate  231 , the second image  201   d  of second image group  201   b  is compared with the first image  201   c  of the first image group  201   a  so as to determine a difference therebetween in terms of an object&#39;s position, and the object is retrieved as an effective moving object upon determination of the object as lying within the detecting region  232  defined in the virtual gate  231  and moving in a direction substantively equal to the detecting direction  233 . “Substantively the same with” means the difference between the direction in which the object moves and the detecting direction  233  defined in the virtual gate  231  falls within a predetermined range. 
         [0045]    Referring to  FIG. 3A , which is a flowchart of a method of detecting a moving object according to a third preferred embodiment of the present invention, the method comprises the following steps. 
         [0046]    At step  30 , an image-set  301  (for example, images taken by a surveillance camera) is provided. The image-set  301  at least comprises a first image  301   a  and a second image  301   b  correlated in a time series, wherein the first image  301   a  precedes the second image  301   b . The first image  301   a  and the second image  301   b  are images of pedestrians, vehicles, animals, or any visible moving objects. 
         [0047]    Referring to  FIG. 3A  and  FIG. 3B , at step  31 , a detecting area  311  is defined in an appropriate region of the first image  301   a . The detecting area  311  is rectangular or is of any shape adjustable when necessary. The measurement unit of the detecting area  311  is an image block. The image block is preferably of dimensions 8 pixels×8 pixels, or is of any dimensions adjustable when necessary. 
         [0048]    Referring to  FIG. 3A  and  FIG. 3B , at step  32 , the detecting area  311  is moved in a specific direction  321 , so as to form a motion vector  322 . 
         [0049]    Referring to  FIG. 3A ,  FIG. 3B  and  FIG. 3C , at step  33 , the detecting area  311  is combined with the motion vector  322  so as to construct a virtual gate  331 . Referring to  FIG. 3C , the virtual gate  331  constructed is defined with a detecting region  332  and a detecting direction  333 . The detecting direction  333  can be configured flexibly to meet user needs, though the configured detecting direction  333  must be unidirectional and invariable. The motion vector  322  comprises a motion angle and a motion distance, both of which are user-defined. The unit of the motion distance is pixel. 
         [0050]    Referring to  FIG. 3A  and  FIG. 3C , at step  34 , an image picking area  334  is defined in the first image  301   a . The image picking area  334  can be flexibly positioned in the virtual gate  331 , with a retrieval range larger or smaller than the virtual gate  331 , or can be in an offset position with respect to the virtual gate  331 , adjustable at a user&#39;s discretion, so as to meet various user&#39;s needs in terms of monitoring or recording. 
         [0051]    Referring to  FIG. 3A  and  FIG. 3C , at step  35 , with the virtual gate  331 , the second image  301   b  is compared with the first image  301   a  so as to determine a difference therebetween in terms of an object&#39;s position, and the object is retrieved as an effective moving object upon determination of the object as appearing in the image picking area  334 , lying within the detecting region  332  defined in the virtual gate  331 , and moving in a direction substantively the same with the detecting direction  333 . The definition of the phrase “substantively the same with” is the same as that disclosed in the first preferred embodiment and is therefore omitted herein for the sake of brevity. 
         [0052]    The foregoing preferred embodiments are only illustrative of the features and functions of the present invention but are not intended to restrict the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the spirit of the present invention should be encompassed by the appended claims.