Image collation method and apparatus and recording medium storing image collation program

Abstract

An image collation apparatus includes a collation unit, minimum coincidence ratio extraction unit, and determination unit. The collation unit obtains a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other. The minimum coincidence ratio extraction unit obtains a minimum coincidence ratio from coincidence ratios obtained from the collation unit. The determination unit determines that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold. An image collation method is also disclosed.

1 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises first image transformation means for repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit and outputting the first image after the image processing, and    said first collation means obtains the coincidence ratio by collating the first image output from said first image transformation means with the second image every time said first image transformation means performs image processing, wherein    said apparatus further comprises    second image transformation means for repeatedly executing at least one image processing of translation processing and rotation processing for the first image located at a first initial position by a predetermined amount within a predetermined range, and outputting the first image after image processing,    second collation means for obtaining a coincidence ratio by collating the first image output from said second image transformation means with the second image every time said second image transformation means performs image processing, and    storage means for storing a translation amount, rotational angle, or both a translation amount and rotational angle of the first image from the first information position to a current position when the coincidence ratio output from said second collation means becomes maximum, and    said first image transformation means moves the first image to a second initial position set by adding the translation, rotational angle, or translation amount and rotational angle stored in said storage means to the first initial position, and executes at least one of translation processing and rotation processing for the first image.    
   
   
       2 . An apparatus according to  claim 1 , wherein the range predetermined for said first image transformation means is narrower than the range predetermined for said second image transformation means.  
   
   
       3 . An apparatus according to  claim 1 , wherein a collation region in which said second collation means obtains the coincidence ratio is smaller than a collation region in which said first collation means obtains the coincidence ratio.  
   
   
       4 . An apparatus according to  claim 1 , wherein the translation amount, rotational angle, or translation amount and rotational angle by which said second image transformation means moves the first image for each moving operation are larger than the translation amount, rotational angle, or translation amount and rotational angle by which said first image transformation means moves the first image for each moving operation.  
   
   
       5 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises first image transformation means for repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit and outputting the first image after the image processing, and    said first collation means obtains the coincidence ratio by collating the first image output from said first image transformation means with the second image every time said first image transformation means performs image processing, wherein    said apparatus further comprises    reference point detection means for detecting reference points of the first and second images located at the first initial position, and    correction amount computation means for obtaining a translation amount, rotational angle, or both translation amount and rotational angle of the first image which is required to make the reference points of the first and second image coincide with each other, and    said first image transformation means moves the first image to a second initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle obtained by said correction amount computation means to the first initial position, and executes at least one of translation processing and rotation processing for the first image.    
   
   
       6 . An apparatus according to  claim 1 , wherein 
 said apparatus further comprises    reference point detection means for detecting reference points of the first and second images located at the first initial position, and    correction amount computation means for obtaining a translation amount, rotational angle, or both translation amount and rotational angle of the first image which is required to make the reference points of the first and second image coincide with each other, and    said second image transformation means moves the first image to a new first initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle obtained by said correction amount computation means to the first initial position, and executes at least one of translation processing and rotation processing for the first image.    
   
   
       7 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises region designation means for sequentially designating a plurality of collation regions predetermined as regions in which the first and second images are collated with each other, and    said first collation means obtains coincidence ratios by sequentially collating the first and second images with each other in the collation regions designated by said region designation means.    
   
   
       8 . An apparatus according to  claim 7 , wherein 
 said apparatus further comprises computation means for averaging minimum coincidence ratios corresponding to the respective collation regions output from said minimum coincidence ratio extraction means, and    said determination means determines that the first and second images are identical, if the minimum coincidence ratio average output from said computation means is smaller than a predetermined threshold.    
   
   
       9 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises first image transformation means for repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit and outputting the first image after the image processing, and    said first collation means obtains the coincidence ratio by collating the first image output from said first image transformation means with the second image every time said first image transformation means performs image processing, wherein    said apparatus further comprises region designation means for sequentially designating a plurality of collation regions predetermined as regions in which the first and second images are collated with each other, and    said first collation means sequentially obtains a coincidence ratio by collating the first image output from said image transformation means with the second image in each collation region designated by said region designation means every time said first image transformation means performs image processing.    
   
   
       10 . An apparatus according to  claim 9 , wherein 
 said apparatus further comprises computation means for averaging minimum coincidence ratios corresponding to the respective collation regions output from said minimum coincidence ratio extraction means, and    said determination means determines that the first and second images are identical, if the minimum coincidence ratio average output from said computation means is smaller than a predetermined threshold.    
   
   
       11 . An apparatus according to  claim 9 , wherein 
 said apparatus further comprises selection means for comparing minimum coincidence ratios corresponding to the respective collation regions which are output from said minimum coincidence ratio extraction means and sequentially outputting only a predetermined number of minimum coincidence ratios in increasing order, and    said computation means averages the minimum coincidence ratios output from said selection means.    
   
   
       12 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises first image transformation means for repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit and outputting the first image after the image processing, and    said first collation means obtains the coincidence ratio by collating the first image output from said first image transformation means with the second image every time said first image transformation means performs image processing, wherein    said apparatus further comprises image processing means for selecting one of contraction and expansion for one of the first and second images and performing a plurality of different image processes, and    said collation means collates an output from said image processing means with an image having undergone no image processing.    
   
   
       13 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises first image transformation means for repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit and outputting the first image after the image processing, and    said first collation means obtains the coincidence ratio by collating the first image output from said first image transformation means with the second image every time said first image transformation means performs image processing, wherein    said apparatus further comprises image processing means for selecting one of contraction and expansion for one of the first and second images and performing a plurality of different image processes, and    said collation means collates an output from said image processing means with an image having undergone no image processing.    
   
   
       14 . An apparatus according to  claim 13 , wherein said image processing means performs the plurality of different image processes by repeatedly executing image processing for the selected image for every predetermined amount.  
   
   
       15 . An apparatus according to  claim 13 , wherein said image processing means comprises 
 thinning means for decreasing a line width of an input image to a value corresponding to about one pixel, and    expansion means for fattening the image output from said thinning means, and    increases the line width corresponding to about one pixel to a predetermined width, and outputs the image.    
   
   
       16 . An apparatus according to  claim 13 , further comprising storage means for storing an image output from said image processing means and outputting the image to said collation means.  
   
   
       17 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises first image transformation means for repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit and outputting the first image after the image processing, and    said first collation means obtains the coincidence ratio by collating the first image output from said first image transformation means with the second image every time said first image transformation means performs image processing, wherein    said apparatus further comprises    second image transformation means for repeatedly executing at least one of translation processing (shifting) and rotation processing for the first image located at the first initial position within a predetermined range for every predetermined amount, and outputting a first image after the processing,    second collation means for obtaining a coincidence ratio by comparing/collating the first image output from said second transformation means with the second image every time said second image transformation means performs processing, and    storage means for storing a translation amount, rotational angle, or translation amount and rotational angle of the first image from the first initial position to a current position when the coincidence ratio output from said second collation means becomes maximum, and    said first image transformation means moves the first image to a second initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle stored in said storage means to the first initial position, and executes at least one of translation processing and rotation processing for the resultant first image.    
   
   
       18 . An apparatus according to  claim 17 , wherein 
 said apparatus further comprises image processing means for selecting one of contraction and expansion for the second image and performing a plurality of different image processes, and    said storage means for storing the second image output from said image processing means, and    said second collation means obtains a coincidence ratio by comparing/collating the first image output from said second image transformation means with the second image output from said storage means every time said second image transformation means performs processing.    
   
   
       19 . An apparatus according to  claim 17 , wherein the range predetermined for said first image transformation means is narrower than the range predetermined for said second image transformation means.  
   
   
       20 . An apparatus according to  claim 17 , wherein the translation amount, rotational angle, or translation amount and rotational angle by which said second image transformation means moves the first image for each moving operation are larger than the translation amount, rotational angle, or translation amount and rotational angle by which said first image transformation means moves the first image for each moving operation.  
   
   
       21 . An apparatus according to  claim 17 , wherein a collation region in which the coincidence ratio is obtained by said second collation means is smaller than a collation region in which a coincidence ratio is obtained by said first collation means.  
   
   
       22 . An image collation apparatus comprising: 
 first collation means for obtaining a coincidence ratio between first and second images within a printing element range for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios obtained from said first collation means; and    determination means for determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    said apparatus further comprises    maximum coincidence ratio extraction means for obtaining a maximum coincidence ratio from coincidence ratios output from said first collation means, and    computation means for obtaining a difference between the maximum coincidence ratio output from said maximum coincidence ratio extraction means and the minimum coincidence ratio output from said minimum coincidence ratio extraction means, and    said determination means comprises determination means for determining that the first and second images are identical, if the difference output from said computation means is not less than a predetermined threshold, wherein    said apparatus further comprises region designation means for sequentially designating a plurality of collation regions predetermined as regions in which the first and second images are collated with each other, and    said first collation means obtains coincidence ratios by sequentially collating the first image output from said image transformation means with the second image within a collation region designated by said region designation means every time said first image transformation means performs image processing.    
   
   
       23 . An apparatus according to  claim 22 , wherein 
 said apparatus further comprises image processing means for selecting one of contraction and expansion for one of the first and second images and performing a plurality of different image processes, and    said first collation means collates an output from said image processing means with an image having undergone no image processing.    
   
   
       24 . An image collation apparatus comprising: 
 first collation means for obtaining a relationship between first and second images for each collation unit by collating the first and second images with each other;    minimum coincidence ratio extraction means for obtaining a minimum coincidence ratio from coincidence ratios in the relationship obtained from said first collation means;    determination means for determining that the first and second images are identical, if the extracted coincidence ratio is smaller than a predetermined threshold; and    region designation means for sequentially designating a plurality of collation regions predetermined as regions in which the first and second images are collated with each other,    wherein said first collation means obtains coincidence ratios by sequentially collating the first and second images within the collation regions designated by said region designation means.    
   
   
       25 . An apparatus according to  claim 24 , wherein 
 said apparatus further comprises image processing means for selecting one of contraction and expansion for one of the first and second images and performing a plurality of different image processes, and    said first collation means collates an output from said image processing means with an image having undergone no image processing.    
   
   
       26 . An image collation method comprising: 
 a first collation step of obtaining a coincidence ratio in a predetermined range between first and second images in each collation unit by collating the first and second images with each other;    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios obtained in the first collation step; and    a determination step of determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    the method further comprises a first image transformation step of repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit, and    in the first collation step, a coincidence ratio is obtained by collating the obtained first image after image processing with the second image, wherein    the method further comprises    a second image transformation step of repeatedly executing at least one image processing of translation processing and rotation processing for the first image located at a first initial position by a predetermined amount within a predetermined range, and obtaining the first image after image processing,    a second collation step of obtaining a coincidence ratio by collating the first image after the image processing with the second image every time image processing is performed for the first image, and    a storage step of storing a translation amount, rotational angle, or both a translation amount and rotational angle of the first image from the first information position to a current position when the coincidence ratio becomes maximum, and    in the first image transformation step, the first image is moved to a second initial position set by adding the translation, rotational angle, or translation amount and rotational angle stored in the storage step to the first initial position, and at least one of translation processing and rotation processing is executed for the first image.    
   
   
       27 . A method according to  claim 26 , wherein the range predetermined in the first image transformation step is narrower than the range predetermined in the second image transformation step.  
   
   
       28 . A method according to  claim 26 , wherein a collation region in which the coincidence ratio is obtained in the second collation step is smaller than a collation region in which the coincidence ratio is obtained in the first collation step.  
   
   
       29 . A method according to  claim 26 , wherein the translation amount, rotational angle, or translation amount and rotational angle by the first image is moved in the second image transformation step for each moving operation are larger than the translation amount, rotational angle, or translation amount and rotational angle by which the first image is moved in the first image transformation step for each moving operation.  
   
   
       30 . An image collation method comprising: 
 a first collation step of obtaining a coincidence ratio in a predetermined range between first and second images in each collation unit by collating the first and second images with each other;    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios obtained in the first collation step; and    a determination step of determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    the method further comprises a first image transformation step of repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit, and    in the first collation step, a coincidence ratio is obtained by collating the obtained first image after image processing with the second image, wherein    the method further comprises    a reference point detection step of detecting reference points of the first and second images located at the first initial position before the respective steps, and    a correction amount computation step of obtaining a translation amount, rotational angle, or both translation amount and rotational angle of the first image which is required to make the reference points of the first and second image coincide with each other, and    the first image transformation step comprises a step of moving the first image to a second initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle obtained in the correction amount computation step to the first initial position, and executing at least one of translation processing and rotation processing for the first image.    
   
   
       31 . A method according to  claim 26 , wherein 
 the method further comprises    a reference point detection step of detecting reference points of the first and second images located at the first initial position before the respective steps, and    a correction amount computation step of obtaining a translation amount, rotational angle, or both translation amount and rotational angle of the first image which is required to make the reference points of the first and second image coincide with each other, and    the second image transformation step comprises a step of moving the first image to a new first initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle obtained in the correction computation step to the first initial position, and executing at least one of translation processing and rotation processing for the first image.    
   
   
       32 . An image collation method comprising: 
 a first collation step of obtaining a coincidence ratio in a predetermined range between first and second images in each collation unit by collating the first and second images with each other;    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios obtained in the first collation step; and    a determination step of determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    the method further comprises a first image transformation step of repeatedly executing at least one of translation processing and rotation processing for the first image within a predetermined range for each collation unit, and    in the first collation step, a coincidence ratio is obtained by collating the obtained first image after image processing with the second image, wherein    the method further comprises    a maximum coincidence ratio extraction step of obtaining a maximum coincidence ratio from coincidence ratios output in the first collation step, and    a computation step of obtaining a difference between the maximum coincidence ratio and the minimum coincidence ratio, and    in the determination step, it is determined that the first and second images are identical, if the difference is not less than a predetermined threshold, wherein    the method further comprises a region designation step of sequentially designating a plurality of collation regions predetermined as regions in which the first and second images are collated with each other, and    coincidence ratios are obtained by sequentially collating the first and second images with each other in the collation regions.    
   
   
       33 . A method according to  claim 32 , wherein 
 the method further comprises an image processing step of selecting one of contraction and expansion for one of the first and second images and performing a plurality of different image processes, and    the first and second images are collated with each other by collating the image having undergone the image processing with an image having undergone no image processing.    
   
   
       34 . An image collation method comprising: 
 a first collation step of obtaining a relationship between first and second images for each collation unit by collating the first and second images with each other;    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios in the relationship obtained in the first collation step;    a determination step of determining that the first and second images are identical, if the extracted coincidence ratio is smaller than a predetermined threshold; and    a region designation step of sequentially designating a plurality of collation regions predetermined as regions in which the first and second images are collated with each other,    wherein coincidence ratios are obtained by sequentially collating the first and second images within the collation regions.    
   
   
       35 . A method according to  claim 34 , wherein 
 the method further comprises an image processing step of selecting one of contraction and expansion for one of the first and second images and performing a plurality of different image processes, and    the first and second images are collated with each other by collating the image having undergone the image processing with an image having undergone no image processing.    
   
   
       36 . A recording medium storing an image collation program for causing a computer to execute 
 a first collation step of obtaining a coincidence ratio in a predetermined range between first and second images in each collation unit by collating the first and second images with each other,    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios obtained in the first collation step, and    a determination step of determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    the program further comprises    a second image transformation step of repeatedly executing at least one image processing of translation processing and rotation processing for the first image located at a first initial position by a predetermined amount within a predetermined range, and obtaining the first image after image processing,    a second collation step of obtaining a coincidence ratio by collating the first image after the image processing with the second image every time image processing is performed for the first image, and    a storage step of storing a translation amount, rotational angle, or both a translation amount and rotational angle of the first image from the first information position to a current position when the coincidence ratio becomes maximum, and    in the first image transformation step, the first image is moved to a second initial position set by adding the translation, rotational angle, or translation amount and rotational angle stored in the storage step to the first initial position, and at least one of translation processing and rotation processing is executed for the first image.    
   
   
       37 . A medium according to  claim 36 , wherein the range predetermined in the first image transformation step is narrower than the range predetermined in the second image transformation step.  
   
   
       38 . A medium according to  claim 36 , wherein a collation region in which the coincidence ratio is obtained in the second collation step is smaller than a collation region in which the coincidence ratio is obtained in the first collation step.  
   
   
       39 . A medium according to  claim 36 , wherein the translation amount, rotational angle, or translation amount and rotational angle by the first image is moved in the second image transformation step for each moving operation are larger than the translation amount, rotational angle, or translation amount and rotational angle by which the first image is moved in the first image transformation step for each moving operation.  
   
   
       40 . A recording medium storing an image collation program for causing a computer to execute 
 a first collation step of obtaining a coincidence ratio in a predetermined range between first and second images in each collation unit by collating the first and second images with each other,    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios obtained in the first collation step, and    a determination step of determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    the program further comprises    a reference point detection step of detecting reference points of the first and second images located at the first initial position before the respective steps, and    a correction amount computation step of obtaining a translation amount, rotational angle, or both translation amount and rotational angle of the first image which is required to make the reference points of the first and second image coincide with each other, and    the first image transformation step comprises a step of moving the first image to a second initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle obtained in the correction amount computation step to the first initial position, and executing at least one of translation processing and rotation processing for the first image.    
   
   
       41 . A recording medium storing an image collation program for causing a computer to execute 
 a first collation step of obtaining a coincidence ratio in a predetermined range between first and second images in each collation unit by collating the first and second images with each other,    a minimum coincidence ratio extraction step of obtaining a minimum coincidence ratio from coincidence ratios obtained in the first collation step, and    a determination step of determining that the first and second images are identical, if the extracted minimum coincidence ratio is smaller than a predetermined threshold, wherein    the program further comprises    a reference point detection step of detecting reference points of the first and second images located at the first initial position before the respective steps, and    a correction amount computation step of obtaining a translation amount, rotational angle, or both translation amount and rotational angle of the first image which is required to make the reference points of the first and second image coincide with each other, and    the second image transformation step comprises a step of moving the first image to a new first initial position set by adding the translation amount, rotational angle, or translation amount and rotational angle obtained in the correction computation step to the first initial position, and executing at least one of translation processing and rotation processing for the first image.