Abstract:
The present invention relates to an image comparison apparatus and method in which images are acquired using a photograph unit and comparing them with a registration of memorized images. The photograph unit acquires a plurality of images of the photograph object during a period from detection of the photograph object by the object detection sensor until a press of a button. After which, the acquired image is compared with previously memorized registration images and a comparison result indicating whether or not a match exists is outputted.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an image comparison apparatus for photographing, for example, a face of a person and making a comparison and a check, and more particularly to an apparatus and method for acquiring images and comparing them with previously memorized registration images and outputting a match if one exists. 
   DESCRIPTION OF THE RELATED ART 
   In general, in this kind of image comparison apparatus, an image of a person, acquired by using a camera, is checked against previously registered registration images so that the identity of the person in question is confirmed. 
   For example, in the case where the image comparison apparatus is applied to a gate function for managing those entering and exiting a room, as shown in  FIG. 7 , an image comparison apparatus  71  comprise an illumination device  72 , a camera  73 , a person detection sensor  74 , and a photograph start check button  75 , the apparatus  71 , is typically attached to a door  76  or a wall surface in the vicinity of the door. 
   In the case where a person  77  enters or exits a room, the image comparison apparatus  71 , when the person  77  stops at a check position and presses down the check button  75 , photographs the face of the person  77  approaching the camera  73 , and the photographed face image is compared with previously registered face images to check and confirm consistence/inconsistence, and provides the basis for the entrance and exit being permitted or the entrance and exit being restricted of the person. 
   In this case, as shown by the image information acquisition curve  81  of  FIG. 8 , at the time when the person stops at the check position suitable for photographing by the camera and presses down the check button, the face image of the person can be obtained most accurately. On the other hand, there is known that as the person goes away from the position of the check button it becomes more difficult to accurately capture the face image of the person, and there is a tendency that the accuracy and stability of image information is lowered. 
   When the check button is pressed down, if the person closes the eyes, opens the mouth, or looks away, causing the face image to appear different from the registered image, even if the person is the person in question, it is judged that the face image is a poor image and a recheck operation will check the image again. 
   This recheck operation is repeated until the number of operations reaches the number of predetermined retry times, and if check confirmation can not be made, an input operation using a personal identification key or readout using a check card will be carried out. 
   However, the number of retry operations are increased due to the recheck, it is inconvenient to the person attempting to enter or exit a room, and, a smooth use cannot be realized. Additionally, there is an increased processing time and delay at the entrance and exit. There also is an increased amount of labor to execute a check operation. 
   SUMMARY OF THE INVENTION 
   The present invention is to provide an image comparison apparatus and method, which has a high check function in which when an acquired image is obtained when a button for check confirmation is pressed down, and a plurality of images prior to the check button being pressed and are checked and confirmed. 
   According to an aspect of the present invention, an image comparison apparatus in which an image of a photograph object is acquired by using photograph means, and in a case where a button for check confirmation is pressed down, the acquired image is compared with information concerning previously memorized registration images, and a comparison result is outputted, the image comparison apparatus characterized in that an object detection sensor for detecting existence of the photograph object is provided, the photograph means acquires a plurality of images of the photograph object during a period from detection of the photograph object by the object detection sensor to a press of the button, and in a case where the button is pressed, at least one of the plurality of acquired images is compared with the information concerning the previously memorized registration image. 
   As a result, even if a check poor image is produced at the time of check of the photograph object when the button for check confirmation is pressed down, since the check can be made by using a complementary image obtained at the timing before that, the image suitable for check judgment of the photograph object can always be ensured at the time of check, a recheck operation is omitted, and a check processing can be carried out in a short time. 
   According to another aspect of the present invention, an image comparison method comprises the steps of detecting existence of a photograph object, capturing a plurality of images of the photograph object in a case where the photograph object is detected, detecting a press of a button for check confirmation, comparing at least one of the plurality of captured images with information concerning previously memorized registration images when the press of the button is detected, and outputting a comparison result. 
   If the photograph object is checked by the procedure of such comparison and check steps, even if a suitable check image is not obtained at the point of time when the button for check confirmation is pressed down, the check confirmation can be made by using another image, so that it becomes unnecessary to repeatedly press down the button, and the check process can be completed by one operation. 
   According to another aspect of the present invention, an image comparison center apparatus compares a captured image with information concerning registration images previously memorized in memory means, and outputs a comparison result, in which the image comparison center apparatus is characterized in that a plurality of captured images of a same object are successively compared with the registration images memorized in the memory means, and as a result of the comparison a proper judgment result is outputted in a case where there is a similar image satisfying a check judgment threshold, and an improper judgment result is outputted in a case where there is no similar image satisfying the check judgment threshold in the plurality of images. 
   If there is a similar image satisfying the check judgment threshold in the plurality of photographed images, the proper judgment result is outputted, and if there is no similar image satisfying the check judgment threshold, the improper judgment result is outputted, so that the plurality of images concerning the same object are used on a screen for check judgment, and check confirmation with high accuracy can be made. 
   According to still another aspect of the present invention, an image comparison system captures an image of a photograph object by use of a photograph means, compares the captured image with registration images previously memorized in memory means, and outputs a comparison result, in which the image comparison system is characterized in that a plurality of captured images of a same object are successively compared with the information concerning the registration images memorized in the memory means, and as a result of the comparison, a proper judgment result is outputted in a case where there is a similar image satisfying a check judgment threshold, and an improper judgment result is outputted in a case where there is no similar image satisfying the check judgment threshold in the plurality of images. 
   Since the check properness can be confirmed by successively comparing the plurality of photographed images with the the registration images memorized in the memory means, an image coincident with the registered image can be obtained without fail. 
   According to still another aspect of the present invention, where an image acquired at the point of time when the button for check confirmation is pressed down is a check poor image, a check is made by using the image acquired nearest in time to the time the button is pressed from the plurality of images acquired prior to the press of the button. 
   According to still another aspect of the present invention, a display means for displaying a check state at the time of check is provided. 
   In this invention the check state, such as check success and check failure is displayed and guided at the time of the check, a photographed person can look at the display guide and can immediately determine confirmation, and the check processing can be executed while a sense of security is given to the photographed person. 
   In the present invention the photograph object includes the face of a check person, and the whole and specific portions of various objects. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view showing an image comparison apparatus of the present invention; 
       FIG. 2  is a diagram showing an image information acquisition curve and a photograph state of a camera; 
       FIG. 3  is an explanatory view showing a lean angle state of a check object person who uses the image comparison apparatus of the present invention; 
       FIG. 4  is a control circuit block diagram of an image comparison system of the present invention; 
       FIG. 5  is a flowchart showing a check processing operation using the image comparison system of the present invention; 
       FIG. 6  is a flowchart subsequent to  FIG. 5 ; 
       FIG. 7  is a schematic side view showing a use state of a conventional image comparison apparatus; and 
       FIG. 8  is a diagram showing an image information acquisition curve and a photograph timing of a camera when a photograph is taken by the conventional image comparison apparatus. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An embodiment of the present invention will be hereinafter described in detail with reference to the drawings. 
   The drawings show an image comparison apparatus installed at an image acquisition side of an image comparison system in which a face of a person is photographed and is checked. As shown in  FIG. 1 , the image comparison apparatus  11  is constructed by installing an operation panel  12  having a check data acquisition function on a door surface which is used for entrance and exit. 
   The image comparison apparatus comprises an operation panel  12  that is attached at the height of a person&#39;s face, an illumination device  13  for illuminating the face is disposed at its upper portion, a camera  14 , a person detection sensor  15 , a check result display LED  16 , a check count display LED  17 , and a check start button  18  are disposed at its intermediate portion, and a personal identification key  19  and a card reader  20  are disposed at its lower portion. 
   In the illumination device  13 , a plurality of illuminating LEDs are arranged, and illumination is made toward the forward position of the face height. The roughness state of a face of a person approaching the camera  14  is clearly illuminated to raise the face image acquisition performance of the camera  14 . 
   The foregoing camera  14  photographs a face image by using a CCD camera or the like, and when a person approaches the front of the camera  14 , the person detection sensor  15  such as a reflection type infrared sensor detects the approach of the person, the camera  14  starts to photograph from the point of time of the detection until the check start button  18  is pressed down. During that period a plurality of face images of the person are photographed. 
   Even if a check poor image is produced in an image acquired at the time when the check start button  18  is pressed down, for the purpose of making a check using a complementary image acquired at a time prior to the plurality of images as the complement are acquired. 
   Thereafter, when the check start button  18  is pressed down, it is judged to be a check request of a person and the check is started. At this time, a check result of consistence or inconsistence of the person who was checked, is displayed on the check result display LED  16 . The check result display LED  16  is designed such that a light of a blue or red judgment result is turned on at one of two LEDs of different colors to enable recognition at a glance. 
   Besides, at the time of the check, a check state, for example, a first check, or a second or third check due to failure of a check, is displayed in real time by the check count display LED  17  including a plurality of LEDs, so that the person being checked is made to clearly recognize it. 
   Like this, it is possible to recognize the check properness by the lighting display of the check result display LED  16  and it is possible to grasp the check state by looking at the display guide of the check count display LED  17 , so that the person being checked can execute the check processing at ease without having a distrust or a sense of unease at the time of the check use. 
   The person detection sensor is used, for example a light emitting diode for irradiating infrared rays as a light source, a reflection type distance detection function to detect the existence of the person being checked by detecting reflected light of the infrared rays. 
   During the comparison process, not only can the check start button  18  be used, but also the personal identification key  19  may be used, or the card reader  20  may be used, and further, these may be used together. 
   The personal identification key  19  and the card reader  20  have an independent check function, and if the person being checked inputs a given personal identification number for identifying the person being checked by using the personal identification key  19 , check confirmation is made based on the personal identification information and, the door being used for entrance or exit is unlocked. If the card reader  20  is used, the ID data of a card in which the ID data for identifying the person being checked is read out and recognized, the door is unlocked. 
     FIG. 2  shows an image information acquisition curve  21  when the camera photographs the face image of the person being checked. The image information acquisition curve  21  shows that at the time when the check start button  18  is pressed down, the face information of the person being checked can be obtained most accurately and the stability of the image is increased. 
   During the period between the detection of the person being checked by the person detection sensor  15  until the pressing of the check start button  18 , the camera  14  photographs the face image of the person being checked plural times and acquires the images, and in the case where the check start button  18  is pressed, at least one of the plurality of acquired images is compared with information concerning previously memorized registration images. 
   At the comparison of the images, a proper judgment result is outputted in the case where there is a similar image satisfying a previously determined check judgment threshold, and an improper judgment result is outputted in the case where there is no similar image satisfying the check judgment threshold in the plurality of images. Thus, if the plurality of images concerning the same person being checked are used on the screen for check judgment, check confirmation with high accuracy can be made, and in the case of the registered person being checked, an image coincident with the registered image can be obtained without fail. 
   As a result, even if the expression of the face at the point of time when the check start button  18  is pressed down is changed as compared with that at the normal time and is judged to be a check poor image, a recheck can be made by using the plurality of images previously taken. 
   Particularly, since the person being checked is photographed plural times and the plurality of face images are obtained, the check confirmation can be made by any of the images, and the check processing can be completed by one button press operation without troubling the person being checked. 
   When the plurality of acquired images of the person being checked are checked, the last image  23  acquired in order of time prior to the button being pressed  22  is used to make the check. The check can be made in order of timing near the image acquired at the point of time of the press of the button, which is most suitable for the check. 
   Accordingly, as shown in  FIG. 3A , in the case where the face of the person  31  being checked is directed toward the front, an image suitable for the check can be obtained. On the other hand, in the case where the face of the check object person  31  is directed obliquely upward as shown in  FIG. 3B , or in the case where it is directed obliquely downward as shown in  FIG. 3C , a slight lean angle θis produced in the eyes with respect to a front camera  32 . When the lean angle is θ=0°, the image becomes more stable, and when it exceeds θ=15°, a feature amount of the face cannot be accurately calculated, and the image becomes unstable. 
   Accordingly, when only one image at the time of the press of the button is used, limitation occurs in the check processing. Therefore, the check is complemented by an after-mentioned control processing. 
     FIG. 4  is a control circuit block diagram of an image comparison system, which is constructed by an image comparison center apparatus  41  for controlling the respective instruments provided on the operation panel  12  of the image comparison apparatus  11 , and a CPU  42 . The CPU  42  controls respective circuit devices along a program stored in a memory  43 , and the control data is memorized in the memory  43 . 
   An image capture device  44  acquires an image photographed by the camera  14 , and causes it to be memorized in the memory  43 . The acquired image is displayed on a monitor  46  for monitoring through a display control portion  45 . 
   A first input/output control portion  47  controls respective input/output data of the illumination device  13 , the person detection sensor  15 , the check result display LED  16 , the check count display LED  17 , and the check start button  18 , and a second input/output control portion  48  controls input from a keyboard  49  for an entrance and exit monitor room. 
   An RS232C communication portion  50  has a communication connection function to transmit input data from the card reader  20  and the personal identification key  19  to the CPU  42 . 
   A registration file  51  is provided as a database file at the time of registration of a face image, and the data of the face image feature amount of respective registered persons is stored here. 
   The CPU  42  checks the face image information of the person photographed by the camera  14  against the previously registered registration information, and determines the consistence or inconsistency of the person being checked, and based on the judgment result, permission of entrance and exit or the restriction of entrance and exit is carried out. 
   The entrance and exit state is displayed by the monitor  46  connected to the image comparison center apparatus  41 , and the data input and the opening control of the door by a supervisor are allowed using the keyboard  49 . 
   A processing operation when a check use is made by using the image comparison system constructed by the preferred embodiment will be described with reference to flowcharts of  FIGS. 5 and 6 . 
   When a person who makes an entrance and exit use approaches the door of a room provided with the image comparison apparatus  11 , the person detection sensor  15  first detects and confirms the presence of a person (step n 1 ). 
   On the basis of a detection signal of the sensor  15 , the camera  14  starts to photograph (step n 2 ), and the image obtained by the camera  14  is stored in the memory  43  of the image comparison center apparatus  41  (step n 3 ). 
   At the time of the image acquisition, after one face image is acquired, a next face image is photographed for grasping a change in the eyes and direction of a face elapses (step n 4 ). 
   A photograph is repeatedly taken until the person being checked presses down the check start button  18 . It is preferable that an upper limit of the number of acquired photographs is fixed, so that a photograph is not unnecessarily taken. When the person being checked presses down the check start button  18  (step n 5 ), the CPU  42  acquires an image of the person being checked immediately (step n 6 ). 
   The CPU  42  compares and checks the acquired face image with previously registered face images, and determines the degree of similarity. At the judgment, the face feature amount of eyes, a nose, a mouth or the like which becomes features at the check time is extracted and are checked (steps n 7  to n 10 ). 
   If the check judgment results in consistence, the check result display LED  16  displays the consistence by lighting (steps n 11  to n 12 ), and the check count display LED  17  displays that the check processing is the first and that the check result is the consistence (steps n 13  to n 14 ), and at the same time, the door for entrance and exit is unlocked, and the entrance and exit of the person being checked is permitted (step n 15 ) 
   On the other hand, in the case where the CPU  42  judges that the check is impossible, an automatic check judgment is repeatedly carried out within the limit of the previously determined number of check times (step n 16 ). 
   For example, when the image acquired immediately after the press of the check start button  18  is checked, and is judged to be a check poor image since the person being checked closes the eyes, opens the mouth or looks away, so that the CPU  42  makes a judgment of improper judgment result, the check result display LED  16  displays check processing failure by lighting (step n 17 ), and at the same time, the check count display LED  17  displays and guides how many times the check processing has been repeated (step n 18 ). At the time of the recheck, after the lights of the check result display LED  16  are put out (step n 19 ), the CPU  42  extracts an image at a time prior to the point of time of the press of the button among the plurality of acquired images of the person being checked and starts to recheck (step n 20 ). 
   If the consistence is not obtained though the recheck is made, the recheck is further made by using the acquired image in order of time prior to the press of the button. If consistence is not obtained, a similar recheck operation is repeatedly carried out, and when the number of operations reaches the previously determined check limit number of times, another check means is shown, and if the person being checked inputs a personal identification number by using the personal identification key  19 , or the card reader  20  is used to read the card data and check confirmation can be made, an entrance and exit gate is unlocked and the entrance and exit is permitted (steps n 21  to n 22 ). 
   However, in the case where the check confirmation cannot be made even if the number reaches the previously determined check limit number of times, or in the case where the improper judgment result is obtained even if the personal identification key  19  or the card reader  20  is used, the improper judgment result is displayed on the check result display LED  16  and the restriction of entrance and exit is made (steps n 23  to n 24 ). 
   In the correspondence of the present invention and the foregoing embodiment, the photograph means of the present invention corresponds to the camera  14 ,  32  of the embodiment, and similarly in the following, the photograph object corresponds to the person being checked  31 , the button for check confirmation corresponds to the check start button  18 , the object detection sensor corresponds to the person detection sensor  15 , the memory means corresponds to the memory  43  or the registration file  51  and the display means corresponds to the check result display LED  16  and the check count display LED  17 . However, the present invention can be applied on the basis of the technical concept recited in the claims, and is not limited only to the structure of the foregoing embodiment. 
   According to the present invention, even if a proper check image can not be obtained at the point of time when a button for check confirmation is pressed down, check confirmation can be made by using another image, so that it becomes unnecessary to repeatedly press down the button, and a check processing can be completed by one button press operation. 
   It is appreciated that the image comparison apparatus is not limited to only checking a person, but include any object that is identifiable by photograph.