Patent Publication Number: US-2022237942-A1

Title: Information processing apparatus, information processing method, and storage medium

Description:
This application is a National Stage Entry of PCT/JP2019/021160 filed on May 28, 2019, the contents of all of which are incorporated herein by reference, in their entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to an information processing apparatus, an information processing method, and a storage medium. 
     BACKGROUND ART 
     PTL 1 discloses an apparatus for processing a fingerprint image into fine lines. The apparatus disclosed in PTL 1 includes sweat gland detection means for detecting positions of sweat glands in the fingerprint image, sorting means for selecting the sweat glands belonging to the same ridge line, and connecting means for connecting the sweat glands belonging to the same ridge. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: Japanese Patent Laid-Open No. H02-153478 
       
    
     SUMMARY 
     Technical Problem 
     However, the apparatus disclosed in PTL 1 is unable to properly connect sweat glands when the ridge lines are extremely curved or when sweat gland pores cannot be partially extracted, which makes it difficult to draw a fine ridge line with high accuracy. 
     It is an object of the disclosure to provide an information processing apparatus, an information processing method, and a storage medium capable of drawing a fine ridge line with high accuracy. 
     Solution to Problem 
     According to one aspect of the disclosure, there is provided an information processing apparatus including: an information acquisition unit that acquires sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores; and a ridge line drawing unit that draws a quasi ridge line based on the sweat gland pore information. 
     According to another aspect of the disclosure, there is provided an information processing method including: acquiring sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores; and drawing a quasi ridge line based on the sweat gland pore information. 
     According to another aspect of the disclosure, there is provided a storage medium storing a program that causes a computer to perform: acquiring sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores; and drawing a quasi ridge line based on the sweat gland pore information. 
     Advantageous Effects 
     According to the disclosure, it is possible to draw a fine ridge line with high accuracy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration of an information processing apparatus according to a first example embodiment. 
         FIG. 2  is a flowchart illustrating an operation of acquiring sweat gland pore information in the information processing apparatus according to the first example embodiment. 
         FIG. 3A  shows an example of a fingerprint image taken by the fingerprint imaging unit. 
         FIG. 3B  shows an example of a fingerprint image taken by the fingerprint imaging unit. 
         FIG. 4A  is a schematic diagram illustrating an example of fingerprint image segmentation processing in the information processing apparatus according to the first example embodiment. 
         FIG. 4B  is a schematic diagram illustrating another example of the fingerprint image segmentation processing in an information processing apparatus according to first example embodiment. 
         FIG. 5  is a schematic diagram illustrating an example of sweat gland pore extraction processing by an O-ring in the information processing apparatus according to first example embodiment. 
         FIG. 6  is a schematic diagram illustrating an example of the sweat gland pore extraction processing by a C-ring in the information processing apparatus according to the first example embodiment. 
         FIG. 7  is a schematic diagram illustrating processing for acquiring direction information of sweat gland pores in the information processing apparatus according to the first example embodiment. 
         FIG. 8A  is a schematic diagram illustrating an example of position information, direction information, and error tolerance range included in sweat gland pore information acquired in an information processing apparatus according to first example embodiment. 
         FIG. 8B  is a schematic diagram illustrating an example of position information, direction information, and error tolerance range included in sweat gland pore information acquired in an information processing apparatus according to first example embodiment. 
         FIG. 9  is a flowchart illustrating matching operation in an information processing apparatus according to a second example embodiment. 
         FIG. 10  is a schematic diagram illustrating an example of matching processing based on position information of sweat gland pores in the information processing apparatus according to the second embodiment. 
         FIG. 11  is a schematic diagram illustrating an example of matching processing based on direction information of sweat gland pores in the information processing apparatus according to the second example embodiment. 
         FIG. 12  is a flowchart illustrating a drawing operation of a quasi ridge line in an information processing apparatus according to a third example embodiment. 
         FIG. 13  is a schematic diagram illustrating an example of connection processing at an intersection in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 14  is a schematic diagram illustrating an example of the quasi ridge drawn by the connection processing at an intersection in the drawing operation of the quasi ridge in the information processing apparatus according to the third example embodiment. 
         FIG. 15  is a schematic diagram illustrating an example of branch connection processing in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 16  is a schematic diagram illustrating an example of the connection processing using a valley line in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 17A  is a schematic diagram illustrating an example of determination processing of a non-valley line portion in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 17B  is a schematic diagram illustrating an example of the determination processing of the non-valley line portion in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 18  is a schematic diagram illustrating an example of interruption processing of drawing in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 19A  is a schematic diagram illustrating another example of the branch connection processing in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 19B  is a schematic diagram illustrating another example of the branch connection processing in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 20  is a schematic diagram illustrating an example of stop processing of the drawing at an endpoint in the drawing operation of the quasi ridge line in the information processing apparatus according to the third example embodiment. 
         FIG. 21  is a block diagram illustrating a configuration of an information processing apparatus according to another example embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Example Embodiment 
     An information processing apparatus and an information processing method according to a first example embodiment of the disclosure will be described with reference to  FIGS. 1 to 8B . 
     First, the configuration of the information processing apparatus according to the example embodiment will be described with reference to  FIG. 1 .  FIG. 1  is a block diagram illustrating a configuration of the information processing apparatus according to the example embodiment. 
     As illustrated in  FIG. 1 , the information processing apparatus  1  according to the example embodiment includes a CPU (Central Processing Unit)  10 , a RAM (Random Access Memory)  12 , a storage unit  14 , an input unit  16 , a fingerprint imaging unit  18 , and a display unit  20 . The CPU  10 , the RAM  12 , the storage unit  14 , the input unit  16 , the fingerprint imaging unit  18 , and the display unit  20  are connected to the common bus  22 . 
     The information processing apparatus  1  is not particularly limited, but is, for example, a computer apparatus such as a laptop or desktop personal computer. The information processing apparatus  1  may be, for example, a smartphone, a tablet type personal computer, or the like. 
     The CPU  10  operates by executing the program stored in the storage unit  14 , and functions as a control unit for controlling the operation of the entire information processing apparatus  1 . The CPU  10  executes a program stored in the storage unit  14  to perform various processes as the information processing apparatus  1 . The RAM  12  provides a memory area necessary for the operation of the CPU  10 . Specifically, the CPU  10  executes a program stored in the storage unit  14  to function as a functional unit as described below. 
     The information processing apparatus  1  according to the example embodiment functions as a feature information acquisition apparatus for acquiring and registering sweat gland pore information which is feature information relating to the sweat gland pore imaged on a fingerprint image of a finger of a target person to be registered from the fingerprint image. Since the CPU  10  of the information processing apparatus  1  functions as a feature information acquisition apparatus, the CPU  10  functions as an image acquisition unit  102 , an image division unit  104 , a sweat gland pore extraction unit  106 , a direction detection unit  108 , an error setting unit  110 , a reliability acquisition unit  112 , and a registration unit  114 , as will be described later. The sweat gland pore extraction unit  106  and the direction detection unit  108  function as an information acquisition unit for acquiring sweat gland pore information for each sweat gland pore. The information processing apparatus functioning as the feature information acquisition apparatus will be described in the example embodiment. 
     The information processing apparatus  1  also functions as a matching apparatus for identifying the target person by performing matching of the sweat gland pore information of the target person to be identified and the sweat gland pore information of the registered registrant. In order to function as the matching apparatus, the CPU  10  of the information processing apparatus  1  functions as a matching unit  116  and a determination unit  118 , as will be described later. The information processing apparatus  1  functioning as matching apparatus will be described with reference to a second example embodiment. 
     Further, the information processing apparatus  1  also functions as a ridge line drawing apparatus for drawing a quasi ridge line which is a pseudo ridge line based on sweat gland pore information acquired from the fingerprint image. Since the CPU  10  of the information processing apparatus  1  functions as the ridge line drawing apparatus, it functions as the ridge line drawing unit  120  as will be described later. The information processing apparatus  1  functioning as a ridge line drawing apparatus will be described with reference to the third example embodiment. 
     The storage unit  14  comprises a storage medium such as a non-volatile memory such as a flash memory, a hard disk drive, or the like. The storage unit  14  stores programs executed by the CPU  10 , data referred to by the CPU  10  when the programs are executed, and the like. 
     The storage unit  14  stores a sweat gland pore information database (DB, Database)  142 . The sweat gland pore information DB  142  registers sweat gland pore information acquired from a fingerprint image of a finger of a registrant associated with personal information of the registrant. The registered sweat gland pore information that is sweat gland pore information registered in the sweat gland pore information DB  142  is matched with sweat gland pore information acquired from a fingerprint image of a finger of a target person to be identified when identifying the target person. 
     An input unit  16  receives input of information, instructions, etc., from an operator to the information processing apparatus  1 . The operator can input an instruction for execution of processing and various kinds of information to the information processing apparatus  1  via the input unit  16 . The input unit  16  is not particularly limited, but includes, for example, a keyboard, a mouse, and the like. The input unit  16  may be formed of, for example, a touch panel incorporated in the display unit  20 . 
     The fingerprint imaging unit  18  is a fingerprint imaging device that images the belly of a finger of a target person to acquire a fingerprint image. The fingerprint imaging unit  18  images a fingerprint image including not only ridge lines and valleys but also sweat gland pores. The fingerprint imaging unit  18 , for example, can image a fingerprint by receiving near-infrared light emitted from a finger, which enters a finger placed with its belly facing the imaging surface of the image sensor, is scattered in the finger, and is then received by the image sensor. The fingerprint imaging unit  18  can adjust the position of the fingerprint in the image area of the fingerprint image to a specific position, for example, by a guide structure for guiding and regulating the position of the finger when the finger is placed on the imaging surface. The method by which the fingerprint imaging unit  18  acquires the fingerprint image is not particularly limited as long as the fingerprint image including sweat gland pores can be acquired, and various methods can be employed. 
     The display unit  20  displays a screen such as a screen of a program for executing various processes in accordance with control by the CPU  10 . The display unit  20  includes, for example, a liquid crystal display, an OLED (Organic Light Emitting Diode) display, and the like. The display unit  20  may be built in the information processing apparatus  1 , which is a laptop or tablet personal computer, or may be an external display provided separately from the information processing apparatus  1 . The display unit  20  may be constituted by a touch panel display in which a touch panel serving as an input unit  16  is incorporated. 
     It should be noted that some or all of the functions of the respective units in the information processing apparatus  1  described above need not necessarily be implemented by a single apparatus, but may be implemented by another external apparatus such as a server. For example, some or all of the functions of the respective units of the CPU  10  may be realized by a CPU of a server communicatively connected to the information processing apparatus  1  via a network. For example, the storage unit  14  may be realized by a storage device of a server, a network storage, or the like, which is communicatively connected to the information processing apparatus  1  via a network. 
     Thus, the information processing apparatus  1  according to the example embodiment is configured. 
     Fingerprints have the inequality of all people, which varies from person to person, and the constancy of life, which does not change throughout life. Therefore, fingerprints have come to be widely used in situations where individual identification is required. However, it has been difficult to extract fingerprint-related features for newborns and infants using conventional techniques. 
     In contrast, the information processing apparatus  1  according to the example embodiment acquires sweat gland pore information including position information about the sweat gland pores and direction information about the sweat gland pores for each of the sweat gland pores as feature information about the sweat gland pores included in the fingerprint image, as will be described below. The information processing apparatus  1  according to the example embodiment can acquire sweat gland pore information from a fingerprint image of a finger of a newborn infant or an infant. The ridge lines of the fingerprint are continuous ridge lines containing sweat gland pores. The location and other characteristics of the sweat glands associated with these ridge lines also vary from person to person. Therefore, the sweat gland pore information acquired by the information processing apparatus  1  according to the example embodiment can be used for identifying an individual including a newborn infant and an infant. Furthermore, since the sweat gland pore information includes not only position information but also direction information, it is possible to specify an individual with high accuracy. 
     It should be noted that the information processing apparatus  1  according to the example embodiment can acquire sweat pore information not only on the fingers of newborn infants and infants but also on the fingers of persons of all ages. 
     The finger for acquiring sweat the gland pore information is not particularly limited. The information processing apparatus  1  according to the example embodiment can acquire the sweat gland pore information on any finger from which a fingerprint image has been acquired. For example, the information processing apparatus  1  can acquire the sweat gland pore information from a fingerprint image of one or more fingers out of a total of 10 fingers of the thumb, index finger, middle finger, ring finger, and little finger of each of a left hand and a right hand. Also, not only the finger, for example, the information processing apparatus  1  can acquire the sweat gland pore information from the finger (toe) mark image for one or a plurality of toes among a total of 10 toes including the first toe, the second toe, the third toe, the fourth toe, and the fifth toe of each of a left foot and a right foot. Furthermore, the information processing apparatus  1  can acquire sweat gland pore information not only on the fingers and toes but also on any part including sweat gland pores and forming patterns on the skin. The information processing apparatus  1  can acquire sweat gland pore information from an image including skin markings other than fingerprints. The skin marking may include any part of the skin pattern, such as fingerprints, palms, footprints, etc. 
     Hereinafter, the acquisition operation for acquiring the sweat gland pore information in the information processing apparatus  1  according to the example embodiment will be described with reference to  FIGS. 2 to 8B .  FIG. 2  is a flowchart illustrating an operation of acquiring the sweat gland pore information in the information processing apparatus  1 .  FIG. 3A  is a diagram illustrating an example of a fingerprint image taken by the fingerprint imaging unit  18 .  FIG. 3B  is an enlarged view of a rectangular area in the fingerprint image shown in  FIG. 3A .  FIG. 4A  is a schematic diagram illustrating an example of the division processing of the fingerprint image in the information processing apparatus  1 .  FIG. 4B  is a schematic diagram illustrating another example of the division processing of the fingerprint image in the information processing apparatus  1 .  FIG. 5  is a schematic diagram illustrating an example of extraction processing of sweat gland pores by an O-ring in the information processing apparatus  1 .  FIG. 6  is a schematic diagram illustrating an example of extraction processing of sweat gland pores by a C-ring in the information processing apparatus  1 .  FIG. 7  is a schematic diagram illustrating acquisition process of the direction information of the sweat gland pore in the information processing apparatus  1 .  FIGS. 8A and 8B  are schematic diagrams illustrating an example of position information, direction information, and error tolerance range included in the sweat gland pore information acquired in the information processing apparatus  1 . The information processing apparatus  1  according to the example embodiment operates to execute an information processing method according to the example embodiment for acquiring the sweat gland pore information. 
     First, as illustrated in  FIG. 2 , the fingerprint imaging unit  18  images a fingerprint of a finger of a target person to register sweat gland pore information (step S 102 ). Thus, the fingerprint imaging unit  18  acquires and outputs a fingerprint image including sweat gland pores of the target person. 
     As shown in  FIGS. 3A and 3B , the fingerprint image F imaged by the fingerprint imaging unit  18  is an image in which the fingerprint is imaged in the rectangular image area A. The fingerprint in the fingerprint image F is imaged so that the longitudinal direction of the finger is along a pair of sides in the longitudinal direction of the image area A. The fingerprint image F is, for example, a 256 gradation image having pixel values corresponding to the unevenness of the belly of the fingertip. In the fingerprint image F, pixels with higher heights are brighter pixels with higher pixel values. In this case, in the fingerprint image F, ridge lines are displayed brighter, valley lines are displayed darker, and sweat gland pores are displayed darker. In the fingerprint image F, the sweat gland pores are dark granular areas arranged in ridge lines which are bright linear areas sandwiched between valley lines which are dark linear areas. The correspondence between the unevenness of the belly of the fingertip and the pixel values may be opposite, and the pixels with higher heights may be darker pixels with lower pixel values. In the following description, a case will be described in which, in the fingerprint image, the higher the height, the brighter the pixel whose pixel value is higher. 
     When the fingerprint image is imaged by the fingerprint imaging unit  18 , the CPU  10  executes the following processing by the functional unit realized by the execution of the program. 
     First, as illustrated in  FIG. 2 , the image acquisition unit  102  acquires the fingerprint image output by the fingerprint imaging unit  18  (step S 104 ). When the position of the fingerprint in the image area of the fingerprint image does not match a specific position, the image acquisition unit  102  can prompt the user to re-image the fingerprint image by, for example, displaying a message on the display unit  20 . In this case, the image acquisition unit  102  can also perform image processing for correcting the fingerprint image so that the fingerprint position matches a specific position. 
     Instead of acquiring the fingerprint image output by the fingerprint imaging unit  18 , the image acquisition unit  102  may acquire the fingerprint image by reading the fingerprint image from the storage medium or by receiving the fingerprint image via the network. 
     Next, the image division unit  104  divides the fingerprint image acquired by the image acquisition unit  102  (step S 106 ). Thus, the image division unit  104  divides the image area of the fingerprint image into a plurality of divided areas which are smaller than the image area. 
     As shown in  FIGS. 4A and 4B , for example, the image division unit  104  can divide the image area A of the fingerprint image F into rectangular divided areas Pik in a grid shape. Herein, i is a positive integer satisfying 1≤i≤m, where m is an integer of 2 or more. k is a positive integer satisfying 1≤k≤n, where n is an integer of 2 or more.  FIGS. 4A and 4B  show a case where m and n are 3, respectively. The plurality of divided areas Pik have the same rectangular shape. In  FIGS. 4A and 4B , the ridge lines are shown in black, and the valleys and sweat gland pores are shown in white for convenience in the fingerprint image. 
     As shown in  FIG. 4A , the image division unit  104  can divide the image area A of the fingerprint image F so that adjacent divided areas do not overlap each other. Further, as illustrated in  FIG. 4B , the image division unit  104  can divide the image area A of the fingerprint image F so that portions of the adjacent divided areas overlap each other.  FIG. 4B  shows a case where half of the divided areas adjacent to each other overlap. 
     It is not necessary for the image division unit  104  to divide the image area A of the fingerprint image F into a plurality of divided areas of the same shape. The image division unit  104  can divide the image area A of the fingerprint image F into a plurality of divided areas having mutually different shapes. The shape of the divided area is not limited to a rectangular shape, and various shapes can be adopted. 
     Next, the sweat gland pore extraction unit  106  extracts a plurality of sweat gland pores from the divided area of the fingerprint image divided by the image division unit  104  (step S 108 ). The sweat gland pore extraction unit  106  can extract the sweat gland pore in the following manner. 
     First, as illustrated in  FIG. 5 , the sweat gland pore extraction unit  106  detects a granular area that fits in the O-ring OR, which is a closed circular ring having a diameter in a predetermined range, in the divided area Pik based on the information on the gradation in the divided area Pik of the fingerprint image. The granular area detected here is an area in a predetermined gradation range, that is, an area in which the height composed of pixels having a predetermined pixel value or less is a predetermined height or less. To fit in the O-ring OR means that a granular area enters the O-ring OR without contacting the O-ring OR. The sweat gland pore extraction unit  106  can detect a granular area while changing the diameter of the O-ring OR within a predetermined range. The sweat gland pore extraction unit  106  extracts the granular area detected by an O-ring OR as a sweat gland pore. In  FIG. 5 , four sweat gland pores are extracted by O-ring OR, and the other sweat gland pores are extracted in the same manner. 
     In the extraction of sweat gland pores by the O-ring OR, a granular area isolated from the valley line can be extracted as a sweat gland pore. On the other hand, in the fingerprint image, a sweat gland pore may be imaged as a granular area connected to the valley line. In the extraction of sweat gland pores by the O-ring OR, it is impossible to detect the granular area connected to the valley line. 
     Therefore, as illustrated in  FIG. 6 , the sweat gland pore extraction unit  106  further detects a granular area that fits in the C-ring CR, which is a partially open circular ring having a predetermined range of diameter in the divided area Pik, based on the information on the gradation in the divided area Pik of the fingerprint image. The C-ring CR is a circular ring having one open portion of a predetermined range of length. The granular area detected here is an area in a predetermined gradation range, that is, an area in which the height composed of pixels having a predetermined pixel value or less is a predetermined height or less. To fit in the C-ring CR means that a granular area enters inside the C-ring CR without contacting the C-ring CR, and a connection part with a valley line of the granular area enters an open portion of the C-ring CR. The sweat gland pore extraction unit  106  can change the diameter of the C-ring CR and the length of the open portion in a predetermined range, and detect a granular area while changing the position of the open portion in the C-ring CR. The sweat gland pore extraction unit  106  also extracts the granular area detected by the C-ring CR as a sweat gland pore.  FIG. 6  shows a state in which four sweat gland pores are extracted by the C-ring CR in addition to the four sweat gland pores extracted by the O-ring OR, and the other sweat gland pores are extracted in the same manner. 
     Thus, the sweat gland pore extraction unit  106  extracts sweat gland pores not only by using the O-ring OR but also by using the C-ring CR, so that the sweat gland pores can be extracted with high accuracy. The sweat gland pore extraction unit  106  extracts the sweat gland pores using the O-ring OR first as described above, or extracts the sweat gland pores using the C-ring CR first among the extractions of the sweat gland pores using the O-ring and the C-ring. In addition, the sweat gland pore extraction unit  106  can execute both extraction of the sweat gland pore using the O-ring OR and extraction of the sweat gland pore using the C-ring CR in parallel. In addition, the sweat gland pore extraction unit  106  can extract sweat gland pores from the divided areas by various methods in addition to the above-described method. 
     Although the sweat gland pore extraction unit  106  uses the O-ring OR, which is a closed ring, and the C-ring CR, which is a partially open ring, for extracting the sweat gland pore, the ring for extracting the sweat gland pore does not necessarily have to be a circular ring. The sweat gland pore extraction unit  106  can use rings of various shapes as closed rings or partially open rings for extracting sweat gland pores for extracting sweat gland pore. 
     Further, as illustrated in  FIG. 2 , the sweat gland pore extraction unit  106  functions as an information acquisition unit for acquiring position information relating to the sweat gland pore, and acquires position information of the sweat gland pore for each of the plurality of extracted sweat gland pores (step S 110 ). In acquiring the position information, the sweat gland pore extraction unit  106  calculates the coordinates of the center of gravity of the granular area extracted as the sweat gland pore in the two-dimensional coordinate system set in the fingerprint image. The sweat gland pore extraction unit  106  acquires coordinate information showing the calculated coordinates of the center of gravity as the coordinate information of the sweat gland pore, which is position information of the sweat gland pore. Thus, the sweat gland pore extraction unit  106  can acquire the coordinate information of the center of gravity of the sweat gland pore as the position information of the sweat gland pore. 
     Note that the sweat gland pore extraction unit  106  can acquire not only coordinate information of the center of gravity of the sweat gland pore but also coordinate information of a specific position of the sweat gland pore as the position information of the sweat gland pore. The position information of the sweat gland pore may be such that the position of the sweat gland pore can be identified. 
     Next, the error setting unit  110  sets an error tolerance range for the position information of the sweat gland pore acquired by the sweat gland pore extraction unit  106  (step S 112 ). The error setting unit  110  can set a range of a predetermined distance or less from the coordinates of the sweat gland pore as an error tolerance range. The error setting unit  110  can relatively set an error tolerance range according to the image size of the fingerprint image. 
     Next, the direction detection unit  108  functions as an information acquisition unit for acquiring direction information relating to the sweat gland pore, and acquires the direction information of the sweat gland pore for each of the plurality of the sweat gland pores extracted by the sweat gland pore extraction unit  106  (step S 114 ). 
     In acquiring the direction information, the direction detection unit  108  specifies the positions of the valley lines V on both sides located in the vicinity of the center of gravity G of the sweat gland pore SP in the ridge line R, as illustrated in  FIG. 7 . Next, the direction detection unit  108  acquires the directions d 1  and d 2  of the valley lines V on both sides at the identified nearest position. Next, as the direction information of the sweat gland pore SP, the direction detection unit  108  acquires information indicating the direction D obtained by averaging the directions d 1  and d 2 , that is, vector information relating to a vector indicating the direction D and passing through the center of gravity G. The direction of the vector in the vector information indicating the direction D can be set arbitrarily or according to a certain rule as either one of the direction along the direction D and the opposite direction. 
     The direction detection unit  108  can acquire, as the direction information of the sweat gland pore, not only information indicating the averaged direction of the valley lines on both sides located nearest to the center of gravity of the sweat gland pore but also information indicating the direction related to the sweat gland pore. The direction information of the sweat gland pore may be a direction related to the sweat gland pore such as a direction at the position of the sweat gland pore of the ridge line where the sweat gland pore is located and a direction corresponding to the shape of the sweat gland pore. 
     Next, as illustrated in  FIG. 2 , the error setting unit  110  sets an error tolerance range for the direction information of the sweat gland pore acquired by the direction detection unit  108  (step S 116 ). The error setting unit  110  can set, as the error tolerance range, a range of not more than a predetermined angle with the direction indicated by the direction information of the sweat gland pore as the center. 
     In this way, the error tolerance ranges are set for the position information and the direction information of the sweat gland pore information. Therefore, even when the finger is deformed or displaced upon acquisition of the fingerprint image, the position information and the directional information can be appropriately matching by absorbing errors caused by the finger&#39;s deformation or displacement. 
     As described above, the error setting unit  110  does not necessarily set the error tolerance ranges for both the position information and the direction information of the sweat gland pore information. The error setting unit  110  can set an error tolerance range to at least one of the position information and the direction information of the sweat gland pore information. 
     Thus, the sweat gland pore extraction unit  106  and the direction detection unit  108  function as a feature information acquisition unit for acquiring sweat gland pore information which is feature information relating to the sweat gland pore, and acquires sweat gland pore information including position information and direction information. The sweat gland pore information includes the error tolerance range set for the position information and the error tolerance set for the direction information. 
       FIGS. 8A and 8B  schematically show sweat gland pore information FS obtained for sweat gland pores extracted in divided areas Pik. The sweat gland pore information FS includes coordinate information of the center of gravity G of the sweat gland pore as the position information of the sweat gland pore. For the coordinate information of the center of gravity G, the error tolerance range E 1  indicating a range of a predetermined distance or less from the coordinate of the center of gravity G which is the coordinate of the sweat gland pore is set. The sweat gland pore information FS includes vector information indicating the direction D obtained by averaging the directions of the valley lines on both sides located near the nearest side as the direction information of the sweat gland pore. For the vector information indicating the direction D, the error tolerance range E 2  indicating a range of a predetermined angle or less around the direction D is set. 
     Note that the timings at which the steps S 110  to S 116  are executed are not limited to the above case. For example, each time a sweat gland pore is extracted in step S 108 , the steps S 110  to S 116  may be executed. For example, after steps S 110  and S 114  are executed, steps S 112  and S 116  may be executed. 
     Next, the reliability acquisition unit  112  acquires reliability information indicating reliability for the divided area from which the sweat gland pore information has been acquired (step S 118 ). The reliability acquisition unit  112  can acquire, for example, the reliability information indicating higher reliability of the divided area as the number of sweat gland pores extracted in the divided area becomes larger. Further, the reliability acquisition unit  112  can acquire the reliability information indicating lower reliability of the divided area, for example, as the area of the area where the pixel value in the divided area is equal to or smaller than a predetermined threshold value and where there is no fingerprint is wider. The reliability acquisition unit  112  can acquire reliability information based on at least either the number of sweat gland pores or the area of the area without fingerprint. The reliability acquisition unit  112  acquires, as the reliability information of the divided area, a reliability score that is a score having a larger value as the reliability of the divided area is higher. The reliability score may be a score having a smaller value as the reliability of the divided area is higher. 
     The timing at which the step S 118  is executed is not limited to the above case. For example, it may be performed following step S 108  of extracting the sweat gland pores. 
     Next, the CPU  10  determines whether or not the processes in steps S 108  to S 118  have been completed for all the divided areas of the fingerprint image (step S 120 ). If it is determined that the processes have not been completed for all the divided areas (step S 120 , NO), the CPU  10  executes the processing of steps S 108  to S 118  for the divided areas whose processing has not been completed. 
     On the other hand, if it is determined that the processes have been completed for all the divided areas (step S 120 , YES), the registration unit  114  registers the sweat gland pore information acquired for the fingerprint image in the sweat gland pore information DB  142  in the storage unit  14  (step  122 ). At the time of registration, the registration unit  114  registers an identification number for uniquely identifying the target person whose fingerprint image was acquired, the sweat gland pore information acquired for each divided area of the fingerprint image, the reliability information of each divided area, and personal information of the target person in association with each other. The personal information is, for example, a name, a sex, a date of birth, a contact, etc. The personal information is inputted, for example, by an operator to the information processing apparatus  1  through the input unit  16 . 
     Thus, the information processing apparatus  1  can acquire and register the sweat gland pore information including the position information and the direction information relating to the sweat gland pores as the feature information relating to the sweat gland pores extracted from the fingerprint image for the target person. 
     In the sweat gland pore information DB  142 , sweat gland pore information of a plurality of registrants is registered and stored by executing the processing for a plurality of target persons. 
     As described above, according to the example embodiment, the sweat gland pore information including not only the position information about the sweat gland pores but also the direction information about the sweat gland pores is acquired as feature information, so that it is possible to acquire the feature information relating to the sweat gland pores that can realize highly accurate identification of an individual. 
     Second Example Embodiment 
     An information processing apparatus and an information processing method according to a second example embodiment of the disclosure will be described with further reference to  FIGS. 9 to 11 . Note that the same components as those in the information processing apparatus and the information processing method according to the first example embodiment described above are labeled with the same references, and the description thereof will be omitted or simplified. 
     In example embodiment, the information processing apparatus  1  functioning as a matching apparatus for identifying a target person by performing matching of the sweat gland pore information of the target person to be identified and the registered sweat gland pore information of the registrant will be described. Since the CPU  10  of the information processing apparatus  1  according to the example embodiment functions as matching apparatus, the CPU  10  further functions as the matching unit  116  and the determination unit  118 , as illustrated in  FIG. 1 . The matching unit  116  includes a position matching unit  1162  and a direction matching unit  1164 . 
     The number of sweat gland pores in a fingerprint is distributed in a specific range according to race. For this reason, it is considered to be difficult to identify individuals with high accuracy simply by matching the number of sweat gland pores. In contrast, in the example embodiment, the sweat gland pore information, which is the feature information including a plurality of pieces of information such as the position information and the direction information, is matched, so that it is possible to identify an individual with high accuracy. 
     The matching operation in the information processing apparatus  1  according to the example embodiment will be described below with reference to  FIGS. 9 to 11 .  FIG. 9  is a flowchart illustrating the matching operation in the information processing apparatus  1 .  FIG. 10  is a schematic diagram illustrating an example of the matching processing based on the position information of the sweat gland pores in the information processing apparatus  1 .  FIG. 11  is a schematic diagram illustrating an example of the matching processing based on the direction information of the sweat gland pores in the information processing apparatus  1 . The information processing apparatus  1  according to the example embodiment operates to execute an information processing method according to the example embodiment for matching the sweat gland pore information. 
     The information processing apparatus  1  acquires the sweat gland pore information, the reliability information, and the like by performing steps S 102  to S 120  illustrated in  FIG. 2  for a fingerprint image of a target person to be identified by matching the sweat gland pore information, as in the case of the first example embodiment. 
     When target sweat gland pore information which is the sweat gland pore information of the target person is acquired from a fingerprint image of the target person to be identified, the CPU  10  performs the following processes by functional units realized by executing a program to matching the sweat gland pore information. 
     First, as illustrated in  FIG. 9 , matching unit  116  acquires target sweat gland pore information (step S 202 ). 
     Next, matching unit  116  reads out and acquires registered sweat gland pore information, which is the sweat gland pore information of the registrant registered in the sweat gland pore information DB  142  of the storage unit  14 , from the sweat gland pore information DB  142  (step S 204 ). 
     The matching unit  116  performs matching for each divided area corresponding to the target sweat gland pore information and the registered sweat gland pore information. Prior to matching for each divided area, the matching unit  116  determines a non-matching divided area, which is a divided area for which matching of the sweat gland pore information is not performed, based on the reliability information of both divided areas corresponding to each other of the target sweat gland pore information and the registered sweat gland pore information (step S 206 ). That is, the matching unit  116  determines both divided areas as the non-matching divided areas when the reliability information of one of the two divided areas corresponding to the target sweat gland pore information and the registered sweat gland pore information shows low the reliability below a certain level. For example, if one of the reliability scores is equal to or less than a predetermined threshold value and indicates a low reliability equal to or less than a predetermined value, the matching unit  116  can determine both divided areas as the non-matching divided areas. Thus, the matching unit  116  matches the sweat gland pore information about the divided areas having a predetermined reliability or higher among the plurality of divided areas. 
     The matching unit  116  matches the target sweat gland pore information and the registered sweat gland pore information for each division area corresponding to each other except the determined non-matching division area as follows. 
     First, the position matching unit  1162  matching the position information of the sweat gland pore included in the divided area of the target sweat gland pore information and the position information of the sweat gland pore included in the divided area of the corresponding registered sweat gland pore information (step S 208 ). Hereinafter, the divided area of the target sweat gland pore information is appropriately referred to as the target divided area, and the divided area of the registered sweat gland pore information is appropriately referred to as the registered divided area. The position matching unit  1162  determines whether or not the position information of the sweat gland pore included in the target division area and the position information of the sweat gland pore included in the registered division area coincide with each other within error tolerance ranges set respectively. Thus, the position matching unit  1162  identifies the set of sweat gland pores matching the position information within the error tolerance ranges. As described above, since the position information is matched in consideration of the error tolerance range, even when deformation or displacement of the finger occurs in acquiring the fingerprint image, the position information can be appropriately matching by absorbing errors due to deformation or displacement of the finger. 
     Specifically, as illustrated in  FIG. 10 , the position matching unit  1162  matches the position information of the sweat gland pore information tFS of the sweat gland pore tSP included in the target divided area tPik and the position information of the sweat gland pore information rFS of the sweat gland pore rSP included in the registered divided area rPik. The position matching unit  1162  matches the position information of the sweat gland pore information tFS and the position information of the sweat gland pore information rFS about the set of the sweat gland pores tSP, rSP which may correspond to each other. 
     Next, as illustrated in  FIG. 9 , the direction matching unit  1164  matches the direction information about the set of sweat gland pores of which the position information coincides within the error tolerance ranges (step S 210 ). The direction matching unit  1164  determines whether or not the direction information of the sweat gland pore included in the target divided area and the direction information of the sweat gland pore included in the registered divided area coincide with each other within error tolerance ranges set for each set of the sweat gland pores. Thus, the direction matching unit  1164  identifies a set of sweat gland pores in which the direction information coincides within error tolerance ranges. As described above, since the direction information is matched in consideration of the error tolerance range, even when deformation, displacement or the like of the finger occurs in acquiring the fingerprint image, the direction information can be appropriately matched by absorbing errors due to deformation, displacement or the like of the finger. 
     Specifically, as illustrated in  FIG. 11 , the direction matching unit  1164  matches the direction information of the sweat gland pore information tFS and the direction information of the sweat gland pore information rFS about the set of the sweat gland pore tSP and rSP whose position information coincides within the error tolerance ranges. 
     Next, as illustrated in  FIG. 9 , based on the results of the matching performed by the position matching unit  1162  and the direction matching unit  1164 , the matching unit  116  calculates a matching score for each divided area showing the matching result (step S 212 ). The matching unit  116  calculates a higher area-specific matching score as the number of sets of the sweat gland pores in which both the position information and the direction information coincide within the error tolerance ranges becomes larger. Note that the elevation of the area-specific matching score may be reversed. That is, the matching unit  116  can also calculate a lower area-specific matching score as the number of sets of the matched sweat gland pore becomes larger. In this case, for the reliability score of the divided area, a score having a smaller value can be used as the reliability score of the divided area becomes higher. 
     Next, the matching unit  116  determines whether or not the processes in steps S 208  to S 212  have been completed for all divided areas except the non-matching divided areas (step S 214 ). If it is determined that the processes have not been completed for all the divided areas (step S 214 , NO), the matching unit  116  executes the processes of steps S 208  to S 212  for the divided areas for which processing has not been completed. 
     On the other hand, when it is determined that the processes have been completed for all the divided areas (Step S 214 , YES), the matching unit  116  acquires the reliability information for each of the target divided areas and the registration divided areas excluding the non-matching divided areas (step S 216 ). 
     Next, the matching unit  116  calculates a total matching score reflecting the reliability information based on the area-specific matching score and the reliability information (step S 218 ). The matching unit  116  can calculate the total matching score as follows. First, the matching unit  116  calculates a weighted score for each of the area-specific matching scores calculated for each divided area by multiplying the area-specific matching scores by the reliability scores of the corresponding target divided areas and the registration divided areas. Then, the matching unit  116  sums the weighted scores calculated for each of matching scores by area to calculate the total matching score. 
     When calculating the weighted score, the matching unit  116  can multiply various weights instead of multiplying the area-specific matching score by the reliability scores of the target divided area and the registration divided area as weights. For example, the matching unit  116  may multiply the area-specific matching score for each area by a lower score of either the reliability score of the target divided area or the reliability score of the registered divided area as a weight. Further, for example, the matching unit  116  can also multiply the area-specific matching score for each area by the average value of the reliability score of the target divided area and the reliability score of the registered divided area as a weight. 
     The determination unit  118  determines whether or not the target person is a registrant based on the total matching score calculated by the area-specific matching score which is the matching result for each divided area and the reliability score which is reliability information of the divided area as follows. 
     First, the determination unit  118  determines whether or not the total matching score calculated by matching unit  116  is equal to or greater than a predetermined threshold (step S 220 ). In the case where the height of matching score for each area is reversed as described above, the determination unit  118  can determine by reversing the comparison with the threshold value. 
     If it is determined that the total matching score is not less than a predetermined threshold value (step S 220 , YES), the determination unit  118  determines that matching of the target sweat gland pore information and the registered sweat gland pore information coincide (step S 222 ). In this case, the determination unit  118  determines that the target person to be identified is a registrant of the registered sweat gland pore information who has performed matching, and specifies the target person. 
     Next, the determination unit  118  outputs the matching result indicating that the target sweat gland pore information coincides with the registered sweat gland pore information and information about the registrant of the registered sweat gland pore information coinciding with the target sweat gland pore information (step S 224 ). The determination unit  118  can acquire and output, as the matching result, the personal information of the registrant associated with the registered sweat gland pore information matching the target sweat gland pore information from the sweat gland pore information DB  142 . The determination unit  118  can output the total matching score as the matching result. The determination unit  118  can display matching result on the display unit  20  and output the matching result, for example. The determination unit  118  can also output, for example, the matching result by voice from a speaker (not shown). 
     The determination unit  118  can output a probability indicating that the target person is a registrant based on the total matching score, instead of identifying the target person as a registrant. 
     Thus, the determination unit  118  can identify the target person from whom the target sweat gland pore information has been acquired as the registrant of the registered sweat gland pore information that matches the target sweat gland pore information. 
     On the other hand, if it is determined that the total matching score is less than a predetermined threshold value (step S 220 , NO), the determination unit  118  determines that matching of the target sweat gland pore information and the registered sweat gland pore information do not coincide (step S 226 ). In this case, the determination unit  118  determines that the target person to be identified is not a registrant of the registered sweat gland pore information for which the matching is performed. 
     Next, the determination unit  118  outputs the matching result indicating that the target sweat gland pore information does not match the registered sweat gland pore information (step S 228 ). The determination unit  118  can output the total matching score as the matching result. The determination unit  118  can display the matching result on the display unit  20  and output the matching result, for example. The determination unit  118  can also output, for example, the matching result by voice from a speaker (not shown). The determination unit  118  may omit the output of matching result when the target sweat gland pore information does not match the registered sweat gland pore information. 
     Next, the determination unit  118  determines whether or not matching with the matching targets of the plurality of registered sweat gland pore information registered in the sweat gland pore information DB  142  is completed (step S 230 ). The determination unit  118  can set all of the plurality of registered sweat gland pore information registered in the sweat gland pore information DB  142  as the matching target. Further, the determination unit  118  can narrow down a part of the plurality of registered sweat gland pore information to be the matching target. The determination unit  118  can narrow down the matching targets by using, for example, information such as gender and date of birth included in the personal information of the registrant associated with the registered sweat gland pore information. 
     When it is determined by the determination unit  118  that the matching is not completed (Step S 230 , NO), the CPU  10  proceeds to step S 204 , and executes the matching of the target sweat gland pore information with the registered sweat gland pore information which is not matched. 
     On the other hand, when the determination unit determines that the matching has been completed (step S 230 , YES), the determination unit  118  outputs a failure result indicating that the identification of the target person from which the target sweat gland pore information has been acquired has failed (step S 232 ). The determination unit  118  can display the failure result on the display unit  20  and output the failure result, for example. In addition, the determination unit  118  can output, for example, a failure result by voice from a speaker (not shown). 
     As described above, according to example embodiment, the sweat gland pore information including the position information and the direction information relating to the sweat gland pore is matched to identify the target person, so that it is possible to identify an individual with high accuracy. 
     Third Example Embodiment 
     An information processing apparatus and an information processing method according to a third example embodiment of the disclosure will be described further with reference to  FIGS. 12 to 20 . Note that the same components as those in the information processing system and the information processing method according to the first and second example embodiments described above are labeled with the same references, and the description thereof will be omitted or simplified. 
     In the example embodiment, the information processing apparatus  1  functioning as a ridge line drawing apparatus for drawing a quasi ridge line, which is a quasi ridge line, based on the sweat gland pore information including the position information and the direction information acquired from a fingerprint image will be described. The information processing apparatus  1  draws the thinned quasi ridge line. Since the CPU  10  of the information processing apparatus  1  according to the example embodiment functions as a ridge line drawing apparatus, the CPU  10  further functions as the ridge line drawing unit  120 , as illustrated in  FIG. 1 . The drawing of the quasi ridge line includes generating image data of the quasi ridge line, storing the image data of the generated image in a storage medium such as the RAM  12  or the storage unit  14 , and displaying the quasi ridge line on the display unit  20 . 
     Hereinafter, the drawing operation of the quasi ridge line in the information processing apparatus  1  according to the example embodiment will be described with reference to  FIGS. 12 to 20 .  FIG. 12  is a flowchart illustrating the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIG. 13  is a schematic diagram illustrating an example of connection processing at an intersection in the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIG. 14  is a schematic diagram illustrating an example of the quasi ridge line drawn by connection processing at an intersection in the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIG. 15  is a schematic diagram illustrating an example of branch connection processing in the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIG. 16  is a schematic diagram illustrating an example of connection processing using a valley line in a drawing operation of a quasi ridge line in the information processing apparatus  1 .  FIGS. 17A and 17B  are schematic diagrams illustrating an example of the determination processing of the non-valley line portion in the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIG. 18  is a schematic diagram illustrating an example of interruption processing of drawing in the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIGS. 19A and 19B  are schematic diagrams illustrating another example of the branch connection processing in the drawing operation of the quasi ridge line in the information processing apparatus  1 .  FIG. 20  is a schematic diagram illustrating an example of the stop processing of the drawing at an endpoint in the drawing operation of the quasi ridge line in the information processing apparatus  1 . The information processing apparatus  1  according to the example embodiment operates to execute an information processing method according to the example embodiment for drawing the quasi ridge line. 
     The information processing apparatus  1  executes steps S 102  to S 120  illustrated in  FIG. 2  to acquire the sweat gland pore information, the reliability information, and the like, as in the case of the first example embodiment, for the fingerprint image of the target person on which the quasi ridge line is to be drawn. The information processing apparatus  1  can draw the quasi ridge line following the registration of the sweat gland pore information by the first example embodiment. It should be noted that the information processing apparatus  1  does not necessarily need to acquire the reliability information when drawing the quasi ridge line. The information processing apparatus  1  can also read out and acquire the sweat gland pore information of the target person from the sweat gland pore information DB  142  or the like in the storage unit  14 . 
     When the sweat gland pore information is acquired from a fingerprint image of a target person to draw the quasi ridge line, the CPU  10  draws the quasi ridge line by executing the following processing by a functional unit realized by execution of a program. The CPU  10  can draw the quasi ridge line for the entire fingerprint image, or can draw the quasi ridge line for a part of a plurality of divided areas obtained by dividing the fingerprint image, for example, a divided area having a reliability score equal to or higher than a predetermined value. 
     First, as illustrated in  FIG. 12 , the ridge line drawing unit  120  acquires the sweat gland pore information acquired from the fingerprint image of the target person (step S 302 ). 
     Next, the ridge line drawing unit  120  identifies two sweat gland pores located adjacent to each other in the same ridge line based on the position information included in the sweat gland pore information (step S 304 ). 
     Next, the ridge line drawing unit  120  calculates, for each of the identified two sweat gland pores, an extension line that is a straight line corresponding to the position information and the direction information included in the sweat gland pore information (step S 306 ). In this case, specifically, as illustrated in  FIG. 13 , the ridge line drawing unit  120  calculates the extension line EL along the direction D passing through the center of gravity G of the sweat gland pore SP as the extension line according to the position information and the direction information included in the sweat gland pore information, based on the sweat gland pore information FS of the sweat gland pore SP. Thus, the ridge line drawing unit  120  calculates the extension line which is a straight line passing through the position indicated by the position information and along the direction indicated by the direction information. 
     The ridge line drawing unit  120  draws the quasi ridge line in the following manner based on the extension line which is a straight line corresponding to the position information and the direction information of the sweat gland pore information thus calculated. 
     First, as illustrated in  FIG. 12 , the ridge line drawing unit  120  determines whether or not the extension lines corresponding to the position information and the direction information of the two identified sweat gland pores intersect in the ridge line where both of the sweat gland pores are located without crossing over the valley line (step S 308 ). Specifically, as illustrated in  FIG. 13 , the ridge line drawing unit  120  determines whether or not the extension line EL of one sweat gland pore SP of the two identified sweat gland pores SP intersects the extension line EL of the other sweat gland pore SP within the ridge line R. 
     As shown in  FIG. 12 , when it is determined that the extension lines intersect within the ridge line (Step S 308 , YES), the ridge line drawing unit  120  draws the quasi ridge line connecting the two sweat gland pores through the intersection of the extension lines (step S 310 ). In this case, specifically, as illustrated in  FIG. 13 , the extension line EL of one sweat gland pore SP out of the two identified sweat gland pores SP intersects the extension line EL of the other sweat gland pore SP at the intersection PX within the ridge line R where both sweat gland pores SP are located. The ridge line drawing unit  120  draws a line segment connecting the center of gravity G of one sweat gland pore SP and an intersection PX and a line segment connecting the intersection PX and the center of gravity G of the other sweat gland pore SP as a quasi ridge line QR.  FIG. 14  shows an example in which the quasi ridge line QR is drawn for the divided area Pik shown in  FIG. 8A  or the like.  FIG. 14  shows a case where the quasi ridge line QR is drawn for a part of the sweat gland pores. 
     Thus, the ridge line drawing unit  120  draws the quasi ridge line QR connecting one sweat gland pore SP and the other sweat gland pore SP through the intersection PX where the extension line EL of one sweat gland pore SP intersects with the extension line EL of the other sweat gland pore SP. 
     Further, as illustrated in  FIG. 12 , the ridge line drawing unit  120  determines whether it is possible to connect a branching quasi ridge line to the drawn quasi ridge line (step S 312 ). In this case, specifically, as illustrated in  FIG. 15 , the ridge line drawing unit  120  determines whether one of the two extension lines EL intersecting at the intersection PX intersects the extension line EL of the further other sweat gland pore SP within the ridge line R where the respective sweat gland pores SP are located. If it is determined that the lines intersect each other, the ridge line drawing unit  120  determines that the branching quasi ridge lines can be connected. 
     As illustrated in  FIG. 12 , when it is determined that the branching quasi ridge line can be connected (step S 312 , YES), the ridge line drawing unit  120  draws the branching quasi ridge line connected to the drawn quasi ridge line (step S 314 ). In this case, specifically, as illustrated in  FIG. 15 , one of the two extension lines EL intersecting at the intersection PX further intersects at the intersection PX with the extension line EL of the further other sweat gland pore SP. Regarding the intersection at this intersection PX, the ridge line drawing unit  120  draws a line segment connecting the center of gravity G of one sweat gland pore SP and the intersection PX and a line segment connecting the intersection PX and the center of gravity G of the other sweat gland pore SP as a quasi ridge line QR. Thus, the ridge line drawing unit  120  draws the branching quasi ridge line QR. 
     The processes in steps S 312  and S 314  can be executed independently of the series of processes shown in  FIG. 12 . 
     Next, as illustrated in  FIG. 12 , the ridge line drawing unit  120  determines whether or not the drawing of the quasi ridge line has been completed (step S 316 ). If it is determined that the drawing has not been completed (step S 316 , NO), the ridge line drawing unit  120  proceeds to step S 304  to continue drawing the quasi ridge line. When it is determined that the drawing has been completed (step S 316 , YES), the ridge line drawing unit  120  ends the drawing of the quasi ridge line. 
     If it is determined that the branching quasi ridge cannot be connected (step S 312 , NO), the ridge line drawing unit  120  proceeds to step S 316  and executes the same processing as described above. 
     On the other hand, if it is determined that the extension lines do not intersect within the ridge line (step S 308 , NO), the ridge line drawing unit  120  determines whether or not it is possible to draw a quasi ridge line connecting the sweat gland pores by using the valley line (step S 318 ). When the extension lines do not intersect in the ridge line, as illustrated in  FIG. 16 , the extension line EL of one sweat gland pore SP intersects the valley line V at the intersection PV. The extension line EL of the other sweat gland pore SP intersects the valley line V at another intersection PV. When the length of the valley line V between the two intersections PV is equal to or less than a predetermined threshold, the ridge line drawing unit  120  determines that a quasi ridge line connecting the two sweat gland pores SP can be drawn by using the valley line V. On the other hand, if the length of the valley line V between the two intersections PV exceeds a predetermined threshold, the ridge line drawing unit  120  determines that it is impossible to draw a quasi ridge line connecting the two sweat gland pores SP by using the valley line V. When a quasi ridge line cannot be drawn using the valley line V, the extension line EL of the sweat gland pore SP usually crosses the valley line V in a state orthogonal to or close to the intersection. 
     As shown in  FIG. 12 , when it is determined that the quasi ridge line can be drawn using the valley line (step  318 , YES), the ridge line drawing unit  120  draws the quasi ridge line connecting the sweat gland pores using the valley line (step S 320 ). In this case, specifically, as illustrated in  FIG. 16 , the ridge line drawing unit  120  draws a line segment connecting the center of gravity G of the sweat gland pore SP and the intersection PV and a portion between the two intersections PV of the valley line V as the quasi ridge line QR. The line segment connecting the center of gravity G of the sweat gland pore SP and the intersection PV is a line segment connecting the center of gravity G of one sweat gland pore SP and the intersection PV of the extension line EL and a line segment connecting the center of gravity G of the other sweat gland pore SP and the intersection PV of the extension line EL. 
     Thus, the ridge line drawing unit  120  draws the quasi ridge line QR connecting one sweat gland pore SP and the other sweat gland pore SP through the valley line V between the intersection PV where the extension line EL of one sweat gland pore SP intersects with the valley line V and the intersection PV where the extension line EL of the other sweat gland pore SP intersects with the valley line V. 
     Next, the ridge line drawing unit  120  proceeds to step S 312  and executes the same processing as described above. 
     On the other hand, when it is determined that the quasi ridge line cannot be drawn using the valley line (step S 318 , NO), the ridge line drawing unit  120  determines whether or not the linear portion treated as the valley line crossing the extension line of the sweat gland pore is a non-valley line portion (step S 322 ). The non-valley line portion has the same gradation as the valley line in the fingerprint image, but is actually a portion which is not a valley line, for example, wrinkles, scratches, dust, etc. 
     More specifically, as illustrated in  FIGS. 17A and 17B , the ridge line drawing unit  120  compares the width Wx of the linear portion LX, which is treated as the valley line intersecting at the intersection PV with the extension line EL of the sweat gland pore SP, with the width Wr of the ridge line R where the sweat gland pore SP of the extension line EL is located. The ridge line drawing unit  120  can calculate, as the width Wr of the ridge line R, for example, the interval between the valley lines V on both sides of the nearest vicinity of the sweat gland pore SP. The ridge line drawing unit  120  can calculate, as the width Wr of the ridge line R, for example, the average value of the width of a predetermined range of the ridge line R where the sweat gland pore SP is located. Further, the ridge line drawing unit  120  can calculate the width of the linear portion LX in the same direction as the width Wr of the ridge line R, as the width Wx of the linear portion LX. Although the linear portion LX may be curved or bent,  FIGS. 17A and 17B  show the linear portion LX as a line segment along the same direction as the width Wr of the ridge line R for convenience. The ridge line drawing unit  120  determines whether or not the linear portion LX is a non-valley line part based on a result of comparing the width Wx of the linear portion LX with the width Wr of the ridge line R. 
     First, as illustrated in  FIG. 17A , when the width Wx of the linear portion LX is larger than the width Wr of the ridge line R, that is, when Wx&gt;Wr, the ridge line drawing unit  120  determines that the linear portion LX is a non-valley line portion. In this case, since the width Wx of the linear portion LX is larger than the width Wr of the ridge line R, there is a high probability that the linear portion LX is a non-valley line portion such as a wrinkle. 
     As shown illustrated in  FIG. 17B , when the width Wx of the linear portion LX is smaller than a predetermined ratio of the width Wr of the ridge line R, that is, when Wx&lt;α×Wr, the ridge line drawing unit  120  determines that the linear portion LX is a non-valley line portion. Here, α is a coefficient satisfying 0&lt;α&lt;1. The value of α can be set appropriately, for example, α=0.5. In this case, since the width Wx of the linear portion LX is smaller than a predetermined ratio of the width of the ridge line R, there is a high probability that the linear portion LX is a non-valley line portion such as a dust. 
     On the other hand, when none of the above is satisfied, that is, when α×Wr≤Wx≤Wr, the ridge line drawing unit  120  determines that the linear portion LX is not a non-valley line portion. In this case, the linear portion LX is a valley line and is an end point at which the quasi ridge line stops if the connection of the branching quasi ridge line is not possible as described later. 
     As illustrated in  FIG. 12 , when the linear portion is determined to be a non-valley line portion as described above (step S 322 , YES), the ridge line drawing unit  120  determines that the linear portion is not treated as a valley line and proceeds to step S 304 . Thus, the ridge line drawing unit  120  ignores the linear portion determined as the non-valley line portion and again executes the drawing of the quasi ridge line. 
     On the other hand, if it is determined that the linear portion is not the non-valley portion (step S 322 , NO), the ridge line drawing unit  120  draws a quasi ridge line up to the intersection with the linear portion and interrupts drawing of the quasi ridge (step S 324 ). In this case, specifically, as illustrated in  FIG. 18 , the ridge line drawing unit  120  draws a quasi ridge line QR connecting the intersection PV of the extension line EL of the sweat gland pore SP and the linear portion LX and the center of the gravity G of the sweat gland pore SP. Thus, the ridge line drawing unit  120  draws the quasi ridge line QR up to the intersection PV and interrupts drawing of the quasi ridge line QR. 
     Next, as illustrated in  FIG. 12 , the ridge line drawing unit  120  determines whether it is possible to connect a branching quasi ridge line to the quasi ridge line of which drawing has been interrupted (step S 326 ). In this case, specifically, as illustrated in  FIG. 19A , the ridge line drawing unit  120  sets a virtual area VA corresponding to the width Wr of the ridge line R around the quasi ridge line QR of which drawing is interrupted. The virtual area VA can be set, for example, as an area in which the distance from the quasi ridge line QR is less than half the width Wr of the ridge line R. The ridge line drawing unit  120  determines whether an end part of a virtual area VA of a specific quasi ridge line QR overlaps with an end part of a virtual area VA of another quasi ridge line QR. The ridge line drawing unit  120  determines that the specific quasi ridge line QR line can be connected as a quasi ridge line branching the other two quasi ridge lines QR when the ends of the other two virtual areas VA in opposite directions overlap with the end of the specific virtual area VA from both sides. 
     As illustrated in  FIG. 12 , when it is determined that it is possible to connect the branching quasi ridge line (step S 326 , YES), the ridge line drawing unit  120  connects the branching quasi ridge line to the quasi ridge of which drawing has been interrupted (step S 328 ). In this case, specifically as illustrated in  FIG. 19B , the ridge line drawing unit  120  connects, with respect to the specific quasi ridge line QR, the other two quasi ridge lines QR where the virtual areas VA overlap as branching quasi ridge lines to draw them. The ridge line drawing unit  120  can redraw the quasi ridge line QR so that the connected quasi ridge line QR becomes smooth. 
     Thus, the ridge line drawing unit  120  draws the branching quasi ridge line based on the overlapping of the end portions of the virtual area which is an area set around the drawn quasi ridge line. 
     Next, as illustrated in  FIG. 12 , the ridge line drawing unit  120  proceeds to step S 316  and executes the same processing as described above. 
     On the other hand, if it is determined that the branching quasi ridge cannot be connected (step S 326 , NO), the ridge line drawing unit  120  stops drawing the quasi ridge of which drawing has been interrupted (step S 330 ). In this case, specifically, as illustrated in  FIG. 20 , the ridge line drawing unit  120  stops drawing the quasi ridge line QR with the intersection PV with the valley line which serves as the end of the quasi ridge line QR as an endpoint. 
     Next, as illustrated in  FIG. 12 , the ridge line drawing unit  120  proceeds to step S 316  and executes the same processing as described above. 
     Note that the processes from steps S 322  to S 330  can be executed independently of the series of processes illustrated in  FIG. 12  when a linear portion crossing the extension line of the sweat gland pore in a state orthogonal thereto or close to the orthogonal to thereto is detected. 
     Thus, the ridge line drawing unit  120  draws the thinned quasi ridge line based on the position information and the direction information of the sweat gland pore included in the sweat gland pore information in the fingerprint image from which the sweat gland pore information has been acquired. The ridge line drawing unit  120  can store the image data of the drawn quasi ridge in the storage unit  14  in association with the sweat gland pore information used for drawing. The drawn quasi ridge lines can be used, for example, for a fingerprint matching by a minutia system, a pattern matching system or the like. 
     Thus, according to the example embodiment, since the quasi ridge line is drawn based on the sweat gland pore information including the position information and the direction information of the sweat gland pore, it is possible to draw the thinned ridge line with high accuracy. 
     In the example embodiment, quasi ridge lines are drawn based on the sweat gland pores themselves, so that the sweat gland pores are not erroneously detected as discontinuous valley lines. Therefore, in the example embodiment, since the ridge line is not erroneously divided by the mis-detected valley line, it is possible to realize the drawing of the quasi ridge line with high accuracy. Especially in newborns and infants, sweat gland pores are often mis-detected as discontinuous valley lines because the width of sweat gland pores is relatively large compared to the width of valley lines. Even in such cases, according to the example embodiment, the thinned ridge lines can be drawn with high accuracy. 
     Other Example Embodiment 
     The information processing apparatus described in the example embodiments may be configured as illustrated in  FIG. 21  according to another example embodiment.  FIG. 21  is a block diagram illustrating a configuration of an information processing apparatus according to another example embodiment. 
     As illustrated in  FIG. 21 , the information processing apparatus  1000  according to another example embodiment includes an information acquisition unit  1002  that acquires sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores. The information processing apparatus  1000  includes a ridge line drawing unit  1004  that draws a quasi ridge line based on the sweat gland pore information. 
     According to the information processing apparatus  1000  provided by another example embodiment, the quasi ridge line is drawn based on the sweat gland pore information including not only the position information but also the direction information, so that it is possible to draw a fine ridge line with high accuracy. 
     Modified Example Embodiment 
     The disclosure is not limited to the example embodiments described above, and various modifications are possible. 
     For example, in the example embodiments described above, the case where a fingerprint image is imaged by the fingerprint imaging unit  18  is described as an example, but the disclosure is not limited thereto. The information processing apparatus  1  may not have a fingerprint imaging unit  18 . In this case, the fingerprint image is imaged by a fingerprint imaging device which is a device separate from the information processing apparatus  1 . The information processing apparatus  1  can be configured, for example, to read and acquire a fingerprint image from a storage medium storing the fingerprint image imaged by a fingerprint imaging device, or to receive and acquire a fingerprint image via a network. 
     In addition, in the example embodiments described above, the process of dividing the fingerprint image into the plurality of divided areas and acquiring sweat gland pore information is performed as an example, but the disclosure is not limited to this. The information processing apparatus  1  can also execute processing for acquiring sweat gland pore information without dividing the fingerprint image into a plurality of divided areas. 
     In addition, in the example embodiments described above, the case where the sweat gland pore information is acquired from the fingerprint image is described as an example, but the disclosure is not limited thereto. The information processing apparatus  1  acquires the sweat gland pore information from an image including a skin marking of an area including the sweat gland pores and forming a pattern on the skin, in addition to a fingerprint image, performs matching of the sweat gland pore information, and performs drawing of the quasi ridge line. 
     Further, the scope of each of the example embodiments includes a processing method that stores, in a storage medium, a program that causes the configuration of each of the example embodiments to operate so as to implement the function of each of the example embodiments described above, reads the program stored in the storage medium as a code, and executes the program in a computer. That is, the scope of each of the example embodiments also includes a computer readable storage medium. Further, each of the example embodiments includes not only the storage medium in which the computer program described above is stored but also the computer program itself. 
     As the storage medium, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a compact disc-read only memory (CD-ROM), a magnetic tape, a nonvolatile memory card, or a ROM can be used. Further, the scope of each of the example embodiments includes an example that operates on operating system (OS) to perform a process in cooperation with another software or a function of an add-in board without being limited to an example that performs a process by an individual program stored in the storage medium. 
     The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes. 
     (Supplementary Note 1) 
     An information processing apparatus comprising: 
     an information acquisition unit that acquires sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores; and 
     a ridge line drawing unit that draws a quasi ridge line based on the sweat gland pore information. 
     (Supplementary Note 2) 
     The information processing apparatus according to supplementary note 1, 
     wherein the ridge line drawing unit draws the quasi ridge line based on a straight line corresponding to the position information and the directional information. 
     (Supplementary Note 3) 
     The information processing apparatus according to supplementary note 2, 
     wherein the first sweat gland pore and the second sweat gland pore are located adjacent to each other in a same ridge line, and 
     wherein, when the first straight line of the first sweat gland pore and the second straight line of the second sweat gland pore intersect in the ridge line, the ridge line drawing unit draws the quasi ridge line connecting the first sweat gland pore and the second sweat gland pore through an intersection where the first straight line and the second straight line intersect. 
     (Supplementary Note 4) 
     The information processing apparatus according to supplementary note 2, 
     wherein the first sweat gland pore and the second sweat gland pore are located adjacent to each other in a same ridge line, and 
     wherein, when the first straight line of the first sweat gland pore and the second straight line of the second sweat gland pore do not intersect in the ridge line, the ridge line drawing unit draws the quasi ridge line using a valley line where the first straight line and the second straight line intersect. 
     (Supplementary Note 5) 
     The information processing apparatus according to supplementary note 4, 
     wherein the first straight line and the valley line intersect at a first intersection, and the second straight line and the valley line intersect at a second intersection, and 
     wherein the ridge line drawing unit draws the quasi ridge line connecting the first sweat gland pore and the second sweat gland pore through the valley line between the first intersection and the second intersection. 
     (Supplementary Note 6) 
     The information processing apparatus according to any one of supplementary notes 3 to 5, 
     wherein, when the third straight line of the third sweat gland pore intersect with the first straight line, the ridge line drawing unit draws the quasi ridge line that branches. 
     (Supplementary Note 7) 
     The information processing apparatus according to any one of supplementary notes 2 to 6, 
     wherein the ridge line drawing unit determines whether or not a linear portion where the straight lines intersect is a non-valley portion based on a width of the ridge line where the sweat gland pores are located and a width of the linear portion. 
     (Supplementary Note 8) 
     The information processing apparatus according to supplementary note 7, 
     wherein the ridge line drawing unit ignores the linear portion determined to be the non-valley portion when drawing the quasi ridge line. 
     (Supplementary Note 9) 
     The information processing apparatus according to supplementary note 7, 
     wherein the ridge line drawing unit stops drawing the quasi ridge line at the intersection of the straight line and the linear portion when determines that the linear portion is not the non-valley portion. 
     (Supplementary Note 10) 
     The information processing apparatus according to any one of supplementary notes 1 to 9, 
     wherein the ridge line drawing unit draws the quasi ridge line that branches based on an overlap of end part of an area set around the drawn quasi ridge line. 
     (Supplementary Note 11) 
     The information processing apparatus according to any one of supplementary notes 1 to 10, 
     wherein the information acquisition unit acquires the direction information based on directions of valley lines on both sides of a ridge line where the sweat gland pore is located. 
     (Supplementary Note 12) 
     The information processing apparatus according to any one of supplementary notes 1 to 11, 
     wherein the position information is coordinate information of the center of gravity of the sweat gland pore. 
     (Supplementary Note 13) 
     The information processing apparatus according to any one of supplementary notes 1 to 12, 
     wherein the direction information is information indicating a direction obtained by averaging directions of valley lines on both sides located nearest to the center of gravity of the sweat gland pore. 
     (Supplementary Note 14) 
     The information processing apparatus according to any one of supplementary notes 1 to 13, wherein the skin marking is a fingerprint. 
     (Supplementary Note 15) 
     An information processing method comprising: 
     acquiring sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores; and 
     drawing a quasi ridge line based on the sweat gland pore information. 
     (Supplementary Note 16) 
     A storage medium storing a program that causes a computer to perform: 
     acquiring sweat gland pore information including position information about a sweat gland pore extracted from an image including a skin marking and directional information about the sweat gland pore for each of the sweat gland pores; and 
     drawing a quasi ridge line based on the sweat gland pore information. 
     As described above, although the disclosure has been described with reference to the example embodiments, the disclosure is not limited to the example embodiments described above. Various modifications that may be understood by those skilled in the art can be made to the configuration or details of the disclosure within the scope of the disclosure. 
     REFERENCE SIGNS LIST 
     
         
           1  . . . information processing apparatus 
           10  . . . CPU 
           12  . . . RAM 
           14  . . . storage unit 
           16  . . . input unit 
           18  . . . fingerprint imaging unit 
           20  . . . display unit 
           22  . . . common bus 
           102  . . . image acquisition unit 
           104  . . . image division unit 
           106  . . . sweat gland pore extraction unit 
           108  . . . direction detection unit 
           110  . . . error setting unit 
           112  . . . reliability acquisition unit 
           114  . . . registration unit 
           116  . . . matching unit 
           118  . . . determination unit 
           120  . . . ridge line drawing unit 
           1162  . . . position matching unit 
           1164  . . . direction matching unit