WO2002035453A1 - Fingerprint identifying method and security system using the same - Google Patents

Fingerprint identifying method and security system using the same Download PDF

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Publication number
WO2002035453A1
WO2002035453A1 PCT/KR2001/001798 KR0101798W WO0235453A1 WO 2002035453 A1 WO2002035453 A1 WO 2002035453A1 KR 0101798 W KR0101798 W KR 0101798W WO 0235453 A1 WO0235453 A1 WO 0235453A1
Authority
WO
WIPO (PCT)
Prior art keywords
fingeφrint
scanned
central point
image
blocks
Prior art date
Application number
PCT/KR2001/001798
Other languages
French (fr)
Inventor
Deunggu Lee
Original Assignee
Alpha Engineering Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR10-2000-0062538A external-priority patent/KR100409154B1/en
Priority claimed from KR2020000030385U external-priority patent/KR200224845Y1/en
Priority claimed from KR2020000030384U external-priority patent/KR200219734Y1/en
Application filed by Alpha Engineering Co., Ltd. filed Critical Alpha Engineering Co., Ltd.
Priority to AU2002211049A priority Critical patent/AU2002211049A1/en
Publication of WO2002035453A1 publication Critical patent/WO2002035453A1/en

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/98—Detection or correction of errors, e.g. by rescanning the pattern or by human intervention; Evaluation of the quality of the acquired patterns
    • G06V10/993—Evaluation of the quality of the acquired pattern

Definitions

  • the present invention relates to a finge ⁇ rint identifying method and a security system using the same.
  • a conventional finge ⁇ rint identification system identifies a finge ⁇ rint in such a way that a finge ⁇ rint of a user is scanned by an image input apparatus such as a scanner, and a scanned finge ⁇ rint image is compared with a registered finge ⁇ rint data stored in finge ⁇ rint database by using ridges and minutiae of a finge ⁇ rint.
  • the conventional finge ⁇ rint identification system has many difficulties in determining whether the input finge ⁇ rint is identical to the registered finge ⁇ rint or not. For example, when the finge ⁇ rint image is very oily or very dry, or when a scanned portion of a finge ⁇ rint is too partial to perform a finge ⁇ rint identification, it is very difficult to identify or verify the input finge ⁇ rint.
  • the conventional finge ⁇ rint identification system compares the input finge ⁇ rint image with the registered finge ⁇ rint image regardless of a quality state of the input finge ⁇ rint, when a finge ⁇ rint is not properly scanned, it is very difficult to properly identify a finge ⁇ rint.
  • the convention finge ⁇ rint identification system does not let a user know whether the input finge ⁇ rint is acceptable or not immediately after the finge ⁇ rint is scanned, and why the input finge ⁇ rint is unacceptable. The user therefore has to perform all procedure from the beginning for finge ⁇ rint identification when the input finge ⁇ rint is unacceptable. It is very inconvenient.
  • preferred embodiments of the present invention provide a finge ⁇ rint identifying method which can provide a high quality finge ⁇ rint image.
  • the preferred embodiments of the present invention provide a finge ⁇ rint identification method, comprising: a) determining a quality of a scanned finge ⁇ rint image; b) detecting a central point of the scanned finge ⁇ rint image when the quality of the scanned finge ⁇ rint image is acceptable; c) calculating a gradient of the scanned finge ⁇ rint image when the central point the scanned finge ⁇ rint image is located within a designated region; and d) determining whether the gradient of the scanned finge ⁇ rint imgae is within an allowable error range.
  • the step of (a) includes subdividing the scanned finge ⁇ rint into a plurality of blocks; calculating a gray level of each of the plurality of the blocks to determine whether the block is dry or oily; and determing whether the total number of the dry blocks or the total number of the oily blocks is greater than a critical value or not, wherein the finge ⁇ rint is discriminated as unacceptable when either the total number of the dry blocks or the total number of the oily blocks is greater than the critical value.
  • the step of (b) includes designating a boundary region of the central point by calculating a curvature of the scanned finge ⁇ rint image; determining whether the central point of the scanned finge ⁇ rint image exists or not; detecting the central point of the scanned finge ⁇ rint image; and verifying the detected central point of the scanned finge ⁇ rint image using a Poincare index.
  • the step of (c) includes drawing an imaginary line to pass through the central point of the scanned finge ⁇ rint; calculating direction angles of normal lines at crossing points of the imaginary line and ridges of the finge ⁇ rint; comparing the direction angles of the normal lines of the right ridges of the central point of the scanned finge ⁇ rint with the direction angles of the normal lines of the left ridges of the central point of the scanned finge ⁇ rint; and changing a direction of the imaginary line until an offset value of the direction angles of the normal lines of the right ridges and the left ridges becomes approximate to "0", wherein a direction of a pe ⁇ endicular line to the finally set imaginary line is decided as a gradient of the scanned finge ⁇ rint when the offset value becomes approximate to "0".
  • the present invention further provides an entrance door system, comprising: a finge ⁇ rint scanning portion scanning a finge ⁇ rint; a memory portion storing a registered finge ⁇ rint; a controller a) determining a quality of the scanned finge ⁇ rint image, b) detecting a central point of the scanned finge ⁇ rint image when the quality of the scanned finge ⁇ rint image is acceptable, c) calculating a gradient of the scanned finge ⁇ rint image when the central point of the scanned finge ⁇ rint image is located within a designated region, d) determining whether the gradient of the scanned finge ⁇ rint imgae is within an allowable error range, and e) determining whether the scanned finge ⁇ rint is identical to the registered finge ⁇ rint or not when the gradient of the scanned finge ⁇ rint imgae is within the allowable error range; and an entrance door actuator opening or closing an entrance door in response to a control signal output
  • the entrance door system further includes a display panel displaying a text message stored in the memory portion; a voice output portion outputing a voice message stored in the memory portion; a key pad portion including digit keys, letter keys and function keys; and a call portion for calling an inside staff member.
  • the present invention further provides a cash dispenser, comprising: a bank card reader determining whether a finge ⁇ rint written on the bank card inserted thereinto is identical to a registered finge ⁇ rint or not; a finge ⁇ rint scanning portion scanning a finge ⁇ rint; a memory portion storing the registered finge ⁇ rint; and a controller a) determining a quality of the scanned finge ⁇ rint image, b) detecting a central point of the scanned finge ⁇ rint image when the quality of the scanned finge ⁇ rint image is acceptable, c) calculating a gradient of the scanned finge ⁇ rint image when the central point the scanned finge ⁇ rint image is located within a designated region, d) determining whether the gradient of the scanned finge ⁇ rint imgae is within an allowable error range, and e) determining whether the scanned finge ⁇ rint is identical to the registered finge ⁇ rint or not when the gradient of
  • the cash dispenser further includes a display panel displaying a text message stored in the memory portion; a voice output portion outputing a voice message stored in the memory portion; a key pad portion including digit keys, letter keys and function keys; and a call portion for calling a bank clerk.
  • the finge ⁇ rint identification method can provide a high quality finge ⁇ rint identification. Also, since a user can know whether the input finge ⁇ rint is acceptable or not immediately after the finge ⁇ rint is scanned, and if not, why the input finge ⁇ rint is unacceptable, it is very convenient. In addition, due to a high quality finge ⁇ rint identification, the system such as the entrance door system and the cash dispenser can have a high security.
  • FIG. 1 is a flow chart illustrating a finge ⁇ rint identification method according to an embodiment of the present invention
  • FIGs. 2A to 2C are photographs illustrating a process for calculating a quality of a scanned finge ⁇ rint image
  • FIGs. 3A and 3B are photographs illustrating finge ⁇ rint images having unacceptable quality
  • FIGs. 4A to 4C are photographs illustrating a process of detecting a central point of a scanned finge ⁇ rint image
  • FIG. 5 shows a process of calculating a gradient of a scanned finge ⁇ rint image
  • FIGs. 6A and 6B are photographs illustrating a gradient of a scanned finge ⁇ rint image
  • FIG. 7 is a block diagram illustrating an entrance door system in which the finge ⁇ rint identification method of FIG. 1 is employed;
  • FIG. 8 shows a front panel of the entrance door system of FIG. 7;
  • FIG. 9 is a flow chart illustrating operation of the entrance door system of FIG. 7;
  • FIG. 10 is a block diagram illustrating a cash dispenser in which the finge ⁇ rint identification method of FIG. I is employed.
  • FIG. 11 is a block diagram an appearance of the cash dispenser of FIG. 10.
  • FIG. 1 is a flow chart illustrating a finge ⁇ rint identification method according to an embodiment of the present invention.
  • FIGs. 2A to 2C are photographs illustrating a process for calculating a quality of a scanned finge ⁇ rint image.
  • FIGs. 3A and 3B are photographs illustrating finge ⁇ rint images having unacceptable quality.
  • FIGs. 4A to 4C are photographs illustrating a process of detecting a central point of a scanned finge ⁇ rint image.
  • FIG. 5 shows a process of calculating a gradient of a scanned finge ⁇ rint image.
  • FIGs. 6A and 6B are photographs illustrating a gradient of a scanned finge ⁇ rint image.
  • a user rests his/her finger (e.g., thumb) on a finge ⁇ rint input means such as a fingerprint scanner to scan his/her finge ⁇ rint (step S 102).
  • a quality of the scanned finge ⁇ rint image is decided (step S 104).
  • the scanned finge ⁇ rint image is subdivided into a plurality of blocks. A gray level of each of a plurality of the blocks is calculated. When the gray level of a certain block is relatively low, the block is discriminated as an oily block. When the gray level of the block is relatively high, the block is discriminated as a dry block.
  • the total number of the oily blocks and the dry blocks are calculated, respectively.
  • the scanned finge ⁇ rint image is discriminated as an oily finge ⁇ rint image which is unacceptable.
  • the total number of the dry blocks is greater than a critical value, as shown in FIG. 3B, the scanned finge ⁇ rint image is discriminated as a dry finge ⁇ rint image which is unacceptable.
  • a finge ⁇ rint input strength is controlled (step S106).
  • a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more slightly than before is output to a user through a display panel or a voice output means such as a speaker.
  • a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more strongly than before is output to a user through a display panel or a voice output means such as a speaker.
  • a central point of the scanned finge ⁇ rint is detected (step S108).
  • a boundary region is first designated by calculating a curvature of the scanned finge ⁇ rint image as shown in FIG.
  • step SI10 a Poincare index
  • dots "•" denote a central point of the finge ⁇ rint image.
  • a text message or a voice message that asks to change a contact portion of a user's finger is output to a user through a display panel or a voice output means such as a speaker (step S112).
  • a central point of the scanned finge ⁇ rint is detected, it is determined whether a central point of the scanned finge ⁇ rint is positioned at a proper location or not (step SI 14). When a central point of the scanned finge ⁇ rint is not positioned within a designated region as shown in FIG.
  • a text message or a voice message that asks to change a contact portion of a user's finge ⁇ rint is output to a user through a display panel or a voice output means such as a speaker (step SI 16).
  • a central point of the scanned finge ⁇ rint is positioned within a designated region as shown in FIG. 4B, a gradient of the scanned finge ⁇ rint is calculated (step S118).
  • an imaginary line is first drawn to pass through a central point of the scanned finge ⁇ rint.
  • Direction angles of normal lines at crossing points of the imaginary line and the ridges of the finge ⁇ rint are calculated.
  • the direction angles of the normal lines of the right ridges of a central point of the scanned finge ⁇ rint are compared with the direction angles of the normal lines of the left ridges of a central point of the scanned finge ⁇ rint.
  • a direction of the imaginary line is changed.
  • a direction of a pe ⁇ endicular line to the finally set imaginary line is decided as a gradient of the scanned finge ⁇ rint.
  • arrows denote a gradient of the scanned finge ⁇ rint.
  • step S120 it is determined whether the gradient of the scanned finge ⁇ rint is within an allowable error range or not (step S120).
  • a text message or a voice message that asks to change a gradient of a finge ⁇ rint is output to a user through a display panel or a voice output means such as a speaker (step SI 22).
  • the scanned finge ⁇ rint image is compared with the already registered finge ⁇ rint for a new registration and a fingerprint verification (step S124).
  • the finge ⁇ rint identification method according to the present invention can be used in various industrial fields.
  • FIG. 7 is a block diagram illustrating an entrance door system in which the finge ⁇ rint identification method of FIG. 1 is employed.
  • FIG. 8 shows a front panel of the entrance door system of FIG. 7.
  • the entrance door system includes a sensor portion 12, a keypad portion 14, a call portion 16, a voice output portion 18, a finge ⁇ rint input portion 22, a digital processing portion 24, a memory portion 26, a buffer portion 28, a finge ⁇ rint input portion shutter 32, a controller 34, a comparator 36, a video camera 3, a video phone 42, an entrance door actuator 44, a display panel 48, and a lamp 52.
  • the sensor portion 12 detects a person when the person is positioned within a predetermined distance from an entrance door.
  • the keypad portion 14 includes a plurality of key buttons such as digit keys, letter keys and function keys.
  • the call portion 16 is used to call a person in, e.g., a security area.
  • the voice output portion 18 outputs a voice message to a person outside, e.g., a security area.
  • the finge ⁇ rint input portion 22 scans and receives a finge ⁇ rint image.
  • the digital processing portion 24 reads the scanned finge ⁇ rint image.
  • the memory portion 26 stores text messages, voice messages, registered finge ⁇ rint images, passwords, identification (ID) numbers, user formations, other information required to perform a finge ⁇ rint identification (e.g., a standard gray level and allowable error range of a gradient of the fingerprint image), etc.
  • the buffer portion 28 temporarily stores data input through the key pad portion 14 or a finge ⁇ rint image read by the digital processing portion 24.
  • the finge ⁇ rint input portion shutter 32 opens or close a cover of the finge ⁇ rint input portion 22.
  • the controller 34 controls all components of the entrance door system, and determines whether the scanned finge ⁇ rint image is acceptable or not to output a control signal.
  • the comparator 36 compares an input password, an input ID number and an input finge ⁇ rint with registered ones under a control of the controller 34, respectively.
  • the video phone 42 displays an image of a person outside, e.g., a security area, and a person in e.g., a security area manipulates the video phone 42 to generate a control signal that opens an entrance door.
  • the entrance door actuator 44 closes or opens the entrance door in response to a control signal from the controller 34.
  • the display panel 48 displays a text message or digits input through the key pad portion 14.
  • the lamp 52 indicates an operation state of the sensor portion 12 and the entrance door system.
  • the sensor portion 12 detects the person to output a detecting signal to the controller 34.
  • the controller 34 receives the detecting signal to output a text message or a voice message stored in the memory portion 26 through the display panel 48 or the voice output portion 18 as follows: "Welcome. If you are a guest, please push the call button”. If a detected person is a guest, when the guest pushes the call button of the call portion 16, a staff member inside the entrance door monitors an image of the guest taken by the video camera 38 arranged on the entrance door through the video phone 42.
  • the controller 34 When the staff member outputs a door open signal, the controller 34 receives the door open signal to output a control signal to the entrance door actuator 44, thereby opening the entrance door. After a predetermined time period, the controller 34 outputs a control signal to the entrance door actuator 44 to close the entrance door
  • the person standing in front of the entrance door is a staff member, the person first has to input a password through the key pad portion 14.
  • the input password is temporarily stored in the buffer portion 28 and transferred to the controller 34 and the comparator 36.
  • the controller 34 determines whether the input password is identical to the registered password or not using the comparator 36.
  • the controller 34 outputs a control signal to the finge ⁇ rint input portion shutter 32 to open a cover of the finge ⁇ rint input portion 22.
  • the controller 34 outputs a text message or a voice message through the display panel 48 or the voice output portion 18 as follows: "Please input your finge ⁇ rint".
  • the scanned finge ⁇ rint image is read by the digital processing portion 24 and the read finge ⁇ rint image is temporarily stored in the buffer portion 28.
  • the controller 34 calculates a quality of the read finge ⁇ rint image to determine whether the scanned finge ⁇ rint image is acceptable or not by the method described in the step S104 of FIG. 1.
  • a finge ⁇ rint input strength is controlled.
  • the controller 34 when the scanned finge ⁇ rint image is discriminated as an oily finge ⁇ rint image which is unacceptable, the controller 34 outputs a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more slightly than before through the display panel 48 or the voice output portion 18 as follows: "The finge ⁇ rint is too oily. Please try again”. Also, when the scanned finge ⁇ rint image is discriminated as a dry finge ⁇ rint image, the controller 34 outputs a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more strongly than before through the display panel 48 or the voice output portion 18 as follows: "The finge ⁇ rint is too dry. Please try again”.
  • a central point of the scanned finge ⁇ rint is detected.
  • the controller outputs a text message or a voice message as follows: "Please change a contact portion of your finger and try again”.
  • a gradient of the scanned finge ⁇ rint is calculated in the method described in the step S118.
  • the controller 34 determines whether the gradient of the scanned finge ⁇ rint is within an allowable error range. When the gradient of the scanned finge ⁇ rint is not within an allowable error range, the controller 34 outputs a text message or a voice message that asks to change a gradient of a finge ⁇ rint.
  • the comparator 36 compares the scanned finge ⁇ rint image with the already registered finge ⁇ rint. When the scanned finge ⁇ rint image is identical to the registered finge ⁇ rint, the controller 34 outputs a control signal to the entrance door actuator 44 in response to an output signal of the comparator 36 to open the entrance door.
  • the entrance door system of FIG. 7 can be used in, for example, a household, a company, or a research institute, which require a high security.
  • FIG. 9 is a flow chart illustrating operation of the entrance door system of FIG. 7.
  • the sensor portion 12 detects the person to output a detecting signal to the controller 34 (step S302).
  • the controller 34 receives the detecting signal to output a text message or a voice message stored in the memory portion 26 through the display panel 48 or the voice output portion 18 as follows: "Welcome. If you are a guest, please push the call button" (step S304).
  • the controller 34 When the guest pushes the call button of the call portion 16, the controller 34 output a text message or a voice message as follows: "Please wait” (step S308). Thereafter, the entrance door system finishes its operation and is initialized.
  • the controller 34 When the person does not push the call button in a predetermined time period, the controller 34 outputs a text message or a voice message as follows: "Please input your password and push a confirm button" (step S310).
  • the controller 34 determines whether the input password is identical to the registered password or not (step
  • the controller 34 When the input password is not identical to the registered password, the controller 34 outputs a text message or a voice message as follows: "Password is not correct. Would you please push the call button? (step S314).
  • the controller 34 determines whether the call button is pushed or not (step S316).
  • the entrance door system When the call button is pushed, the entrance door system outputs a text message or a voice message of the step S308 and finishes its operation.
  • the controller 34 When the call button is not pushed in a predetermined time period, the controller 34 outputs a text message or a voice message as follows: "Please input your password and push the confirm button".
  • the controller 34 When the input password is identical to the registered password, the controller 34 outputs a text message or a voice message as follows: "Please input your finge ⁇ rint" (step S318). Thereafter, the controller 34 outputs a control signal to the finge ⁇ rint input portion shutter 32 to open a cover of the finge ⁇ rint input portion 22 (step 320).
  • the controller 34 calculates a quality of the scanned finge ⁇ rint image to determine whether the scanned finge ⁇ rint image is acceptable or not by the method described in the step S 104 of FIG. 1 (step S322).
  • a finge ⁇ rint input strength is controlled. That is, when the scanned finge ⁇ rint image is discriminated as an oily finge ⁇ rint image which is unacceptable, the controller 34 outputs a text message or a voice message that asks to rest his finger on the fingerprint input more slightly than before through the display panel 48 or the voice output portion 18 as follows: "The finge ⁇ rint is too oily. Please try again".
  • the controller 34 outputs a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more strongly than before through the display panel 48 or the voice output portion 18 as follows: "The finge ⁇ rint is too dry. Please try again” (step S324).
  • a central point of the scanned finge ⁇ rint is detected (step S326).
  • the controller outputs a text message or a voice message as follows: "Please change a contact portion of your finger and try again" (step S328).
  • a gradient of the scanned finge ⁇ rint is calculated in the method described in the step S118 of FIG. 1.
  • the controller 34 determines whether the gradient of the scanned finge ⁇ rint is within an allowable error range (step S330). When the gradient of the scanned finge ⁇ rint is not within allowable error range, the controller 34 outputs a text message or a voice message as follows: "Change a gradient of a finge ⁇ rint" (step S332). When the gradient of the scanned finge ⁇ rint is within allowable error range, the controller 34 compares the scanned finge ⁇ rint image with the already registered finge ⁇ rint.
  • the controller 34 When the scanned finge ⁇ rint image is identical to the registered finge ⁇ rint, the controller 34 outputs a text message or a voice message as follows: "Thank you. The finge ⁇ rint is identified”. At the same time, the controller 34 outputs a control signal to the finge ⁇ rint input portion shutter 32 to close the cover of the finge ⁇ rint input portion 22 (step S336).
  • controller 34 outputs a control signal to the entrance door actuator 44 to open the entrance door (step S338).
  • controller 34 outputs a control signal to the entrance door actuator 44 to close the entrance door (step S342).
  • FIG. 10 is a block diagram illustrating a cash dispenser according to the present invention.
  • FIG. 11 is a block diagram an appearance of the cash dispenser of FIG. 10.
  • the cash dispenser includes a sensor portion 212, a bank card reader 214, a call portion 216, a voice output portion 218, a finge ⁇ rint input portion 222, a digital processing portion 224, a memory portion 226, an image memory portion 227, a buffer portion 228, a finge ⁇ rint input portion shutter 232, a controller 234, a comparator 236, a driver 238, a call connection module 242, a camera 244, a display panel 246, a cash outlet 248, and a receipt outlet 250.
  • the memory portion 226 stores voice messages
  • the image memory portion 227 stores finge ⁇ rint images.
  • the sensor portion 212 detects a person standing in front of the cash dispenser, a text message or a voice message which asks to insert the bank card is output.
  • the bank card reader 214 reads a finge ⁇ rint data written on a magnetic portion of a bank card and stores the finge ⁇ rint data in the buffer portion 228 temporarily.
  • the finge ⁇ rint data is transferred to the controller 234 and the comparator 236.
  • the comparator 236 determines whether the finge ⁇ rint data written on the magnetic portion is identical to the registered finge ⁇ rint data stored in the image memory portion 227.
  • the controller 234 When the finge ⁇ rint data of the bank card is identical to the registered finge ⁇ rint data, the controller 234 outputs a control signal to the finge ⁇ rint input portion shutter 232 in response an output signal of the comparator 236 to open a cover of the finge ⁇ rint input portion 222. At the same time, the controller 234 outputs a text message or a voice message that asks to input a finge ⁇ rint through the display panel 220 or the voice output portion 218.
  • a user rests his/her finger (e.g., thumb) on the finge ⁇ rint input portion 222, and the digital processing portion 224 reads a finge ⁇ rint image of the user.
  • the scanned finge ⁇ rint image is temporarily stored in the buffer portion 228 and transferred to the controller 234.
  • the controller 234 calculates a quality of the read finge ⁇ rint image to determine whether the scanned finge ⁇ rint image is acceptable or not by the method described in the step S104 of FIG. 1.
  • a finge ⁇ rint input strength is controlled. That is, when the scanned finge ⁇ rint image is discriminated as an oily finge ⁇ rint image which is unacceptable, the controller 234 outputs a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more slightly than before through the display panel 246 or the voice output portion 218 as follows: "The finge ⁇ rint is too oily. Please try again".
  • the controller 234 outputs a text message or a voice message that asks to rest his finger on the finge ⁇ rint input more strongly than before through the display panel 48 or the voice output portion 218 as follows: "The finge ⁇ rint is too dry. Please try again".
  • a central point of the scanned finge ⁇ rint is detected by the method described in the step SI 10 of FIG. 1.
  • the controller When a central point does not exists in the scanned finge ⁇ rint, or when a central point of the scanned finge ⁇ rint is detected but is not positioned within a designated region, the controller outputs a text message or a voice message as follows: "Please change a contact portion of your finger and try again".
  • a gradient of the scanned finge ⁇ rint is calculated in the method described in the step SI 18 of FIG. 1.
  • the controller 234 determines whether the gradient of the scanned finge ⁇ rint is within allowable error range. When the gradient of the scanned finge ⁇ rint is not within allowable error range, the controller 234 outputs a text message or a voice message that asks to change a gradient of a finge ⁇ rint.
  • the controller 234 compares the scanned finge ⁇ rint image with the already registered finge ⁇ rint. When the scanned finge ⁇ rint image is identical to the registered finge ⁇ rint, the controller 234 outputs a control signal to allow a user to receive a service of the cash dispenser.
  • the driver 238 provides a communication between the call portion 216 and the call connection module 242, thereby calling a bank clerk.
  • the finge ⁇ rint identification method according to the present invention can provide a high quality finge ⁇ rint identification. Also, since a user can know whether the input finge ⁇ rint is acceptable or not immediately after the finge ⁇ rint is scanned, it is very convenient. In addition, due to a high quality finge ⁇ rint identification, the system such as the entrance door system and the cash dispenser can have a high security.

Abstract

A fingerprint identification method includes a) determining a quality of a scanned fingerprint image, b) detecting a central point of the scanned fingerprint image when the quality of the scanned fingerprint image is acceptable, c) calculating a gradient of the scanned fingerprint image when the central point the scanned fingerprint image is located with a designated region, and d) determining whether the gradient of the scanned fingerprint imgae is within an allowable error range.

Description

FINGERPRINT IDENTIFYING METHOD AND SECURITY SYSTEM USING
THE SAME
Technical Field The present invention relates to a fingeφrint identifying method and a security system using the same.
Background Art
A conventional fingeφrint identification system identifies a fingeφrint in such a way that a fingeφrint of a user is scanned by an image input apparatus such as a scanner, and a scanned fingeφrint image is compared with a registered fingeφrint data stored in fingeφrint database by using ridges and minutiae of a fingeφrint.
However, the conventional fingeφrint identification system has many difficulties in determining whether the input fingeφrint is identical to the registered fingeφrint or not. For example, when the fingeφrint image is very oily or very dry, or when a scanned portion of a fingeφrint is too partial to perform a fingeφrint identification, it is very difficult to identify or verify the input fingeφrint.
In other words, since the conventional fingeφrint identification system compares the input fingeφrint image with the registered fingeφrint image regardless of a quality state of the input fingeφrint, when a fingeφrint is not properly scanned, it is very difficult to properly identify a fingeφrint.
In addition, the convention fingeφrint identification system does not let a user know whether the input fingeφrint is acceptable or not immediately after the fingeφrint is scanned, and why the input fingeφrint is unacceptable. The user therefore has to perform all procedure from the beginning for fingeφrint identification when the input fingeφrint is unacceptable. It is very inconvenient.
Disclosure of Invention
To overcome the problems described above, preferred embodiments of the present invention provide a fingeφrint identifying method which can provide a high quality fingeφrint image.
It is another object of the present invention to provide a fingeφrint identification method, which can provide a convenient fingeφrint identification.
It is another object of the present invention to provide a security system with a high security and a convenient fingeφrint identification. In order to achieve the above object, the preferred embodiments of the present invention provide a fingeφrint identification method, comprising: a) determining a quality of a scanned fingeφrint image; b) detecting a central point of the scanned fingeφrint image when the quality of the scanned fingeφrint image is acceptable; c) calculating a gradient of the scanned fingeφrint image when the central point the scanned fingeφrint image is located within a designated region; and d) determining whether the gradient of the scanned fingeφrint imgae is within an allowable error range.
The step of (a) includes subdividing the scanned fingeφrint into a plurality of blocks; calculating a gray level of each of the plurality of the blocks to determine whether the block is dry or oily; and determing whether the total number of the dry blocks or the total number of the oily blocks is greater than a critical value or not, wherein the fingeφrint is discriminated as unacceptable when either the total number of the dry blocks or the total number of the oily blocks is greater than the critical value.
The step of (b) includes designating a boundary region of the central point by calculating a curvature of the scanned fingeφrint image; determining whether the central point of the scanned fingeφrint image exists or not; detecting the central point of the scanned fingeφrint image; and verifying the detected central point of the scanned fingeφrint image using a Poincare index.
The step of (c) includes drawing an imaginary line to pass through the central point of the scanned fingeφrint; calculating direction angles of normal lines at crossing points of the imaginary line and ridges of the fingeφrint; comparing the direction angles of the normal lines of the right ridges of the central point of the scanned fingeφrint with the direction angles of the normal lines of the left ridges of the central point of the scanned fingeφrint; and changing a direction of the imaginary line until an offset value of the direction angles of the normal lines of the right ridges and the left ridges becomes approximate to "0", wherein a direction of a peφendicular line to the finally set imaginary line is decided as a gradient of the scanned fingeφrint when the offset value becomes approximate to "0".
The present invention further provides an entrance door system, comprising: a fingeφrint scanning portion scanning a fingeφrint; a memory portion storing a registered fingeφrint; a controller a) determining a quality of the scanned fingeφrint image, b) detecting a central point of the scanned fingeφrint image when the quality of the scanned fingeφrint image is acceptable, c) calculating a gradient of the scanned fingeφrint image when the central point of the scanned fingeφrint image is located within a designated region, d) determining whether the gradient of the scanned fingeφrint imgae is within an allowable error range, and e) determining whether the scanned fingeφrint is identical to the registered fingeφrint or not when the gradient of the scanned fingeφrint imgae is within the allowable error range; and an entrance door actuator opening or closing an entrance door in response to a control signal output from the controller. The entrance door system further includes a display panel displaying a text message stored in the memory portion; a voice output portion outputing a voice message stored in the memory portion; a key pad portion including digit keys, letter keys and function keys; and a call portion for calling an inside staff member.
The present invention further provides a cash dispenser, comprising: a bank card reader determining whether a fingeφrint written on the bank card inserted thereinto is identical to a registered fingeφrint or not; a fingeφrint scanning portion scanning a fingeφrint; a memory portion storing the registered fingeφrint; and a controller a) determining a quality of the scanned fingeφrint image, b) detecting a central point of the scanned fingeφrint image when the quality of the scanned fingeφrint image is acceptable, c) calculating a gradient of the scanned fingeφrint image when the central point the scanned fingeφrint image is located within a designated region, d) determining whether the gradient of the scanned fingeφrint imgae is within an allowable error range, and e) determining whether the scanned fingeφrint is identical to the registered fingeφrint or not when the gradient of the scanned fingeφrint imgae is within the allowable error range, wherein the cash dispenser operates in response to a control signal output from the controller.
The cash dispenser further includes a display panel displaying a text message stored in the memory portion; a voice output portion outputing a voice message stored in the memory portion; a key pad portion including digit keys, letter keys and function keys; and a call portion for calling a bank clerk.
The fingeφrint identification method according to the present invention can provide a high quality fingeφrint identification. Also, since a user can know whether the input fingeφrint is acceptable or not immediately after the fingeφrint is scanned, and if not, why the input fingeφrint is unacceptable, it is very convenient. In addition, due to a high quality fingeφrint identification, the system such as the entrance door system and the cash dispenser can have a high security.
Brief Description of Drawings
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which like reference numerals denote like parts, and in which:
FIG. 1 is a flow chart illustrating a fingeφrint identification method according to an embodiment of the present invention;
FIGs. 2A to 2C are photographs illustrating a process for calculating a quality of a scanned fingeφrint image;
FIGs. 3A and 3B are photographs illustrating fingeφrint images having unacceptable quality;
FIGs. 4A to 4C are photographs illustrating a process of detecting a central point of a scanned fingeφrint image; FIG. 5 shows a process of calculating a gradient of a scanned fingeφrint image;
FIGs. 6A and 6B are photographs illustrating a gradient of a scanned fingeφrint image;
FIG. 7 is a block diagram illustrating an entrance door system in which the fingeφrint identification method of FIG. 1 is employed; FIG. 8 shows a front panel of the entrance door system of FIG. 7;
FIG. 9 is a flow chart illustrating operation of the entrance door system of FIG. 7;
FIG. 10 is a block diagram illustrating a cash dispenser in which the fingeφrint identification method of FIG. I is employed; and
FIG. 11 is a block diagram an appearance of the cash dispenser of FIG. 10.
Best Mode for Carrying Out the Invention
Reference will now be made in detail to preferred embodiments of the present invention, example of which is illustrated in the accompanying drawings.
FIG. 1 is a flow chart illustrating a fingeφrint identification method according to an embodiment of the present invention. FIGs. 2A to 2C are photographs illustrating a process for calculating a quality of a scanned fingeφrint image. FIGs. 3A and 3B are photographs illustrating fingeφrint images having unacceptable quality. FIGs. 4A to 4C are photographs illustrating a process of detecting a central point of a scanned fingeφrint image. FIG. 5 shows a process of calculating a gradient of a scanned fingeφrint image. FIGs. 6A and 6B are photographs illustrating a gradient of a scanned fingeφrint image.
The fingeφrint identification method according to the present invention is described below with reference to FIG. 1 to FIG. 6B
First, a user rests his/her finger (e.g., thumb) on a fingeφrint input means such as a fingerprint scanner to scan his/her fingeφrint (step S 102). A quality of the scanned fingeφrint image is decided (step S 104). In order to decide a quality of the scanned fingeφrint image, as shown in FIGs. 2A to 2C, the scanned fingeφrint image is subdivided into a plurality of blocks. A gray level of each of a plurality of the blocks is calculated. When the gray level of a certain block is relatively low, the block is discriminated as an oily block. When the gray level of the block is relatively high, the block is discriminated as a dry block. Thereafter, the total number of the oily blocks and the dry blocks are calculated, respectively. When the total number of the oily blocks is greater than a critical value, as shown in FIG. 3A, the scanned fingeφrint image is discriminated as an oily fingeφrint image which is unacceptable. Also, when the total number of the dry blocks is greater than a critical value, as shown in FIG. 3B, the scanned fingeφrint image is discriminated as a dry fingeφrint image which is unacceptable.
Subsequently, when the scanned fingeφrint image is discriminated as unacceptable, a fingeφrint input strength is controlled (step S106). When the scanned fingeφrint image is discriminated as an oily fingeφrint image, a text message or a voice message that asks to rest his finger on the fingeφrint input more slightly than before is output to a user through a display panel or a voice output means such as a speaker. Also, when the scanned fingeφrint image is discriminated as a dry fingeφrint image, a text message or a voice message that asks to rest his finger on the fingeφrint input more strongly than before is output to a user through a display panel or a voice output means such as a speaker. When a quality of the scanned fingeφrint image is discriminated as acceptable by repeatedly performing the step S106, a central point of the scanned fingeφrint is detected (step S108). In order to detect a central point of the scanned fingeφrint, a boundary region is first designated by calculating a curvature of the scanned fingeφrint image as shown in FIG. 4A, and a central point of the scanned fingeφrint is detected. The detected central point of the scanned fingeφrint image is verified using a Poincare index (step SI10). In FIGs. 4B and 4C, dots "•" denote a central point of the fingeφrint image.
When a central point of the scanned fingeφrint is not detected, a text message or a voice message that asks to change a contact portion of a user's finger is output to a user through a display panel or a voice output means such as a speaker (step S112). When a central point of the scanned fingeφrint is detected, it is determined whether a central point of the scanned fingeφrint is positioned at a proper location or not (step SI 14). When a central point of the scanned fingeφrint is not positioned within a designated region as shown in FIG. 4C, a text message or a voice message that asks to change a contact portion of a user's fingeφrint is output to a user through a display panel or a voice output means such as a speaker (step SI 16). When a central point of the scanned fingeφrint is positioned within a designated region as shown in FIG. 4B, a gradient of the scanned fingeφrint is calculated (step S118). In order to calculate a gradient of the scanned fingeφrint, as shown in FIG. 5, an imaginary line is first drawn to pass through a central point of the scanned fingeφrint. Direction angles of normal lines at crossing points of the imaginary line and the ridges of the fingeφrint are calculated. The direction angles of the normal lines of the right ridges of a central point of the scanned fingeφrint are compared with the direction angles of the normal lines of the left ridges of a central point of the scanned fingeφrint. Until an offset value of the direction angles of the normal lines of the right ridges and the left ridges becomes approximate to "0", a direction of the imaginary line is changed. When the offset value becomes approximate to "0", a direction of a peφendicular line to the finally set imaginary line is decided as a gradient of the scanned fingeφrint. In FIGs. 6A and 6B, arrows denote a gradient of the scanned fingeφrint.
Thereafter, it is determined whether the gradient of the scanned fingeφrint is within an allowable error range or not (step S120). When the gradient of the scanned fingeφrint is not within an allowable error range, a text message or a voice message that asks to change a gradient of a fingeφrint is output to a user through a display panel or a voice output means such as a speaker (step SI 22). When the gradient of the scanned fingeφrint is within an allowable error range, the scanned fingeφrint image is compared with the already registered fingeφrint for a new registration and a fingerprint verification (step S124).
The fingeφrint identification method according to the present invention can be used in various industrial fields.
FIG. 7 is a block diagram illustrating an entrance door system in which the fingeφrint identification method of FIG. 1 is employed. FIG. 8 shows a front panel of the entrance door system of FIG. 7.
The entrance door system according to the present invention includes a sensor portion 12, a keypad portion 14, a call portion 16, a voice output portion 18, a fingeφrint input portion 22, a digital processing portion 24, a memory portion 26, a buffer portion 28, a fingeφrint input portion shutter 32, a controller 34, a comparator 36, a video camera 3, a video phone 42, an entrance door actuator 44, a display panel 48, and a lamp 52.
The sensor portion 12 detects a person when the person is positioned within a predetermined distance from an entrance door. The keypad portion 14 includes a plurality of key buttons such as digit keys, letter keys and function keys. The call portion 16 is used to call a person in, e.g., a security area. The voice output portion 18 outputs a voice message to a person outside, e.g., a security area. The fingeφrint input portion 22 scans and receives a fingeφrint image. The digital processing portion 24 reads the scanned fingeφrint image. The memory portion 26 stores text messages, voice messages, registered fingeφrint images, passwords, identification (ID) numbers, user formations, other information required to perform a fingeφrint identification (e.g., a standard gray level and allowable error range of a gradient of the fingerprint image), etc. The buffer portion 28 temporarily stores data input through the key pad portion 14 or a fingeφrint image read by the digital processing portion 24. The fingeφrint input portion shutter 32 opens or close a cover of the fingeφrint input portion 22. The controller 34 controls all components of the entrance door system, and determines whether the scanned fingeφrint image is acceptable or not to output a control signal. The comparator 36 compares an input password, an input ID number and an input fingeφrint with registered ones under a control of the controller 34, respectively. The video phone 42 displays an image of a person outside, e.g., a security area, and a person in e.g., a security area manipulates the video phone 42 to generate a control signal that opens an entrance door. The entrance door actuator 44 closes or opens the entrance door in response to a control signal from the controller 34. The display panel 48 displays a text message or digits input through the key pad portion 14. The lamp 52 indicates an operation state of the sensor portion 12 and the entrance door system.
When a person stands in front of the entrance door within a predetermined distance from the entrance door system of FIG. 7, the sensor portion 12 detects the person to output a detecting signal to the controller 34. The controller 34 receives the detecting signal to output a text message or a voice message stored in the memory portion 26 through the display panel 48 or the voice output portion 18 as follows: "Welcome. If you are a guest, please push the call button". If a detected person is a guest, when the guest pushes the call button of the call portion 16, a staff member inside the entrance door monitors an image of the guest taken by the video camera 38 arranged on the entrance door through the video phone 42. When the staff member outputs a door open signal, the controller 34 receives the door open signal to output a control signal to the entrance door actuator 44, thereby opening the entrance door. After a predetermined time period, the controller 34 outputs a control signal to the entrance door actuator 44 to close the entrance door
Meanwhile, when the person standing in front of the entrance door is a staff member, the person first has to input a password through the key pad portion 14. The input password is temporarily stored in the buffer portion 28 and transferred to the controller 34 and the comparator 36. The controller 34 determines whether the input password is identical to the registered password or not using the comparator 36. When the input password is identical to the registered password, the controller 34 outputs a control signal to the fingeφrint input portion shutter 32 to open a cover of the fingeφrint input portion 22. When the cover of the fingeφrint input portion 22 is opened, the controller 34 outputs a text message or a voice message through the display panel 48 or the voice output portion 18 as follows: "Please input your fingeφrint".
The scanned fingeφrint image is read by the digital processing portion 24 and the read fingeφrint image is temporarily stored in the buffer portion 28. At the same time, the controller 34 calculates a quality of the read fingeφrint image to determine whether the scanned fingeφrint image is acceptable or not by the method described in the step S104 of FIG. 1. When the scanned fingeφrint image is discriminated as unacceptable, a fingeφrint input strength is controlled. That is, when the scanned fingeφrint image is discriminated as an oily fingeφrint image which is unacceptable, the controller 34 outputs a text message or a voice message that asks to rest his finger on the fingeφrint input more slightly than before through the display panel 48 or the voice output portion 18 as follows: "The fingeφrint is too oily. Please try again". Also, when the scanned fingeφrint image is discriminated as a dry fingeφrint image, the controller 34 outputs a text message or a voice message that asks to rest his finger on the fingeφrint input more strongly than before through the display panel 48 or the voice output portion 18 as follows: "The fingeφrint is too dry. Please try again".
When the scanned fingerprint image is discriminated as acceptable by repeatedly performing the step S106, a central point of the scanned fingeφrint is detected. When a central point does not exists in the scanned fingeφrint, or when a central point of the scanned fingeφrint is detected but is not positioned within a designated region, the controller outputs a text message or a voice message as follows: "Please change a contact portion of your finger and try again".
When a central point of the scanned fingeφrint is positioned within a designated region, a gradient of the scanned fingeφrint is calculated in the method described in the step S118. The controller 34 determines whether the gradient of the scanned fingeφrint is within an allowable error range. When the gradient of the scanned fingeφrint is not within an allowable error range, the controller 34 outputs a text message or a voice message that asks to change a gradient of a fingeφrint. When the gradient of the scanned fingeφrint is within allowable error range, the comparator 36 compares the scanned fingeφrint image with the already registered fingeφrint. When the scanned fingeφrint image is identical to the registered fingeφrint, the controller 34 outputs a control signal to the entrance door actuator 44 in response to an output signal of the comparator 36 to open the entrance door.
The entrance door system of FIG. 7 can be used in, for example, a household, a company, or a research institute, which require a high security.
FIG. 9 is a flow chart illustrating operation of the entrance door system of FIG. 7. When a person stands in front of the entrance door within a predetermined distance from the entrance door system of FIG. 7, the sensor portion 12 detects the person to output a detecting signal to the controller 34 (step S302). The controller 34 receives the detecting signal to output a text message or a voice message stored in the memory portion 26 through the display panel 48 or the voice output portion 18 as follows: "Welcome. If you are a guest, please push the call button" (step S304).
When the guest pushes the call button of the call portion 16, the controller 34 output a text message or a voice message as follows: "Please wait" (step S308). Thereafter, the entrance door system finishes its operation and is initialized.
When the person does not push the call button in a predetermined time period, the controller 34 outputs a text message or a voice message as follows: "Please input your password and push a confirm button" (step S310).
When a password is input through the key pad portion 14, the controller 34 determines whether the input password is identical to the registered password or not (step
S312). When the input password is not identical to the registered password, the controller 34 outputs a text message or a voice message as follows: "Password is not correct. Would you please push the call button? (step S314).
The controller 34 determines whether the call button is pushed or not (step S316).
When the call button is pushed, the entrance door system outputs a text message or a voice message of the step S308 and finishes its operation. When the call button is not pushed in a predetermined time period, the controller 34 outputs a text message or a voice message as follows: "Please input your password and push the confirm button".
When the input password is identical to the registered password, the controller 34 outputs a text message or a voice message as follows: "Please input your fingeφrint" (step S318). Thereafter, the controller 34 outputs a control signal to the fingeφrint input portion shutter 32 to open a cover of the fingeφrint input portion 22 (step 320).
The controller 34 calculates a quality of the scanned fingeφrint image to determine whether the scanned fingeφrint image is acceptable or not by the method described in the step S 104 of FIG. 1 (step S322). When the scanned fingeφrint image is discriminated as unacceptable, a fingeφrint input strength is controlled. That is, when the scanned fingeφrint image is discriminated as an oily fingeφrint image which is unacceptable, the controller 34 outputs a text message or a voice message that asks to rest his finger on the fingerprint input more slightly than before through the display panel 48 or the voice output portion 18 as follows: "The fingeφrint is too oily. Please try again". Also, when the scanned fingeφrint image is discriminated as a dry fingeφrint image, the controller 34 outputs a text message or a voice message that asks to rest his finger on the fingeφrint input more strongly than before through the display panel 48 or the voice output portion 18 as follows: "The fingeφrint is too dry. Please try again" (step S324).
When a quality of the scanned fingeφrint image is discriminated as acceptable, a central point of the scanned fingeφrint is detected (step S326). When a central point does not exists in the scanned fingeφrint, or when a central point of the scanned fingeφrint is detected but is not positioned within a designated region, the controller outputs a text message or a voice message as follows: "Please change a contact portion of your finger and try again" (step S328).
When a central point of the scanned fingeφrint is positioned within a designated region, a gradient of the scanned fingeφrint is calculated in the method described in the step S118 of FIG. 1. The controller 34 determines whether the gradient of the scanned fingeφrint is within an allowable error range (step S330). When the gradient of the scanned fingeφrint is not within allowable error range, the controller 34 outputs a text message or a voice message as follows: "Change a gradient of a fingeφrint" (step S332). When the gradient of the scanned fingeφrint is within allowable error range, the controller 34 compares the scanned fingeφrint image with the already registered fingeφrint. When the scanned fingeφrint image is identical to the registered fingeφrint, the controller 34 outputs a text message or a voice message as follows: "Thank you. The fingeφrint is identified". At the same time, the controller 34 outputs a control signal to the fingeφrint input portion shutter 32 to close the cover of the fingeφrint input portion 22 (step S336).
Thereafter, the controller 34 outputs a control signal to the entrance door actuator 44 to open the entrance door (step S338). After the predetermined time period is passed (step S340), the controller 34 outputs a control signal to the entrance door actuator 44 to close the entrance door (step S342).
FIG. 10 is a block diagram illustrating a cash dispenser according to the present invention. FIG. 11 is a block diagram an appearance of the cash dispenser of FIG. 10.
The cash dispenser according to the present invention includes a sensor portion 212, a bank card reader 214, a call portion 216, a voice output portion 218, a fingeφrint input portion 222, a digital processing portion 224, a memory portion 226, an image memory portion 227, a buffer portion 228, a fingeφrint input portion shutter 232, a controller 234, a comparator 236, a driver 238, a call connection module 242, a camera 244, a display panel 246, a cash outlet 248, and a receipt outlet 250. At this point, the memory portion 226 stores voice messages, and the image memory portion 227 stores fingeφrint images.
When the sensor portion 212 detects a person standing in front of the cash dispenser, a text message or a voice message which asks to insert the bank card is output. When the bank card is inserted into the bank card reader 214, the bank card reader 214 reads a fingeφrint data written on a magnetic portion of a bank card and stores the fingeφrint data in the buffer portion 228 temporarily. At the same time, the fingeφrint data is transferred to the controller 234 and the comparator 236. The comparator 236 determines whether the fingeφrint data written on the magnetic portion is identical to the registered fingeφrint data stored in the image memory portion 227. When the fingeφrint data of the bank card is identical to the registered fingeφrint data, the controller 234 outputs a control signal to the fingeφrint input portion shutter 232 in response an output signal of the comparator 236 to open a cover of the fingeφrint input portion 222. At the same time, the controller 234 outputs a text message or a voice message that asks to input a fingeφrint through the display panel 220 or the voice output portion 218.
A user rests his/her finger (e.g., thumb) on the fingeφrint input portion 222, and the digital processing portion 224 reads a fingeφrint image of the user. The scanned fingeφrint image is temporarily stored in the buffer portion 228 and transferred to the controller 234.
At the same time, the controller 234 calculates a quality of the read fingeφrint image to determine whether the scanned fingeφrint image is acceptable or not by the method described in the step S104 of FIG. 1. When the scanned fingeφrint image is discriminated as unacceptable, a fingeφrint input strength is controlled. That is, when the scanned fingeφrint image is discriminated as an oily fingeφrint image which is unacceptable, the controller 234 outputs a text message or a voice message that asks to rest his finger on the fingeφrint input more slightly than before through the display panel 246 or the voice output portion 218 as follows: "The fingeφrint is too oily. Please try again". Also, when the scanned fingeφrint image is discriminated as a dry fingeφrint image, the controller 234 outputs a text message or a voice message that asks to rest his finger on the fingeφrint input more strongly than before through the display panel 48 or the voice output portion 218 as follows: "The fingeφrint is too dry. Please try again". When the scanned fingerprint image is discriminated as acceptable, a central point of the scanned fingeφrint is detected by the method described in the step SI 10 of FIG. 1. When a central point does not exists in the scanned fingeφrint, or when a central point of the scanned fingeφrint is detected but is not positioned within a designated region, the controller outputs a text message or a voice message as follows: "Please change a contact portion of your finger and try again".
When a central point of the scanned fingeφrint is positioned within a designated region, a gradient of the scanned fingeφrint is calculated in the method described in the step SI 18 of FIG. 1. The controller 234 determines whether the gradient of the scanned fingeφrint is within allowable error range. When the gradient of the scanned fingeφrint is not within allowable error range, the controller 234 outputs a text message or a voice message that asks to change a gradient of a fingeφrint. When the gradient of the scanned fingeφrint is within allowable error range, the controller 234 compares the scanned fingeφrint image with the already registered fingeφrint. When the scanned fingeφrint image is identical to the registered fingeφrint, the controller 234 outputs a control signal to allow a user to receive a service of the cash dispenser.
Meanwhile, when a user pushes a call button of the call portion 216 due to, for example, abnormal operation of the cash dispenser, the driver 238 provides a communication between the call portion 216 and the call connection module 242, thereby calling a bank clerk.
Industrial Applicability As described herein before, the fingeφrint identification method according to the present invention can provide a high quality fingeφrint identification. Also, since a user can know whether the input fingeφrint is acceptable or not immediately after the fingeφrint is scanned, it is very convenient. In addition, due to a high quality fingeφrint identification, the system such as the entrance door system and the cash dispenser can have a high security.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

What is claimed is:
1. A fingeφrint identification method, comprising: a) determining a quality of a scanned fingeφrint image; b) detecting a central point of the scanned fingerprint image when the quality of the scanned fingeφrint image is acceptable; c) calculating a gradient of the scanned fingeφrint image when the central point the scanned fingeφrint image is located with a designated region; and d) determining whether the gradient of the scanned fingeφrint imgae is within an allowable error range.
2. The method of claim 1, wherein the step of (a) includes subdividing the scanned fingeφrint into a plurality of blocks; calculating a gray level of each of the plurality of the blocks to determine whether the block is dry or oily; and determining whether the total number of the dry blocks or the total number of the oily blocks is greater than a critical value or not, wherein the fingeφrint is discriminated as unacceptabl when either the total number of the dry blocks or the total number of the oily blocks is greater than the critical value.
3. The method of claim 1, wherien the step of (b) includes designating a boundary region of the central point by calculating a curvature of the scanned fingeφrint image determining whether the central point of the scanned fingeφrint image exists or not; detecting the central point of the scanned fingeφrint image; and verifying the detected central point of the scanned fingeφrint image using a Poincare index.
4. The method of claim 1, wherein the step of (c) includes drawing an imaginary line to pass through the central point of the scanned fingeφrint; calculating direction angles of normal lines at crossing points of the imaginary line and ridges of the fingeφrint; comparing the direction angles of the normal lines of the right ridges of the central point of the scanned fingeφrint with the direction angles of the normal lines of the left ridges of the central point of the scanned fingeφrint; and changing a direction of the imaginary line until an offset value of the direction angles of the normal lines of the right ridges and the left ridges becomes approximate to "0", wherein a direction of a peφendicular line to the finally set imaginary line is decided as a gradient of the scanned fingeφrint when the offset value 'becomes approximate to "0".
5. An entrance door system, comprising: a fingeφrint scanning portion scanning a fingeφrint; a memory portion storing a registered fingeφrint; a controller a) determining a quality of the scanned fingeφrint image, b) detecting a central point of the scanned fingeφrint image when the quality of the scanned fingeφrint image is acceptable, c) calculating a gradient of the scanned fingeφrint image when the central point the scanned fingeφrint image is located with a designated region, d) determining whether the gradient of the scanned fingeφrint imgae is within an allowable error range, and e) determining whether the scanned fingeφrint is identical to the registered fingeφrint or not when the gradient of the scanned fingeφrint imgae is within the allowable error range; and an entrance door actuator opening or closing an entrance door in response to a control signal output from the controller.
6. The system of claim 5, wherein the step of (a) includes subdividing the scanned fingeφrint into a plurality of blocks; calculating a gray level of each of the plurality of the blocks to determine whether the block is dry or oily; and determing whether the total number of the dry blocks or the total number of the oily blocks is greater than a critical value or not, wherein the fingeφrint is discriminated as unacceptabl when either the total number of the dry blocks or the total number of the oily blocks is greater than the critical value.
7. The system of claim 5, wherien the step of (b) includes designating a boundary region of the central point by calculating a curvature of the scanned fingeφrint image determining whether the central point of the scanned fingeφrint image exists or not; detecting the detecting the central point of the scanned fingeφrint image; and verifying the detected central point of the scanned fingeφrint image using a Poincare index.
8. The system of claim 5, wherein the step of (c) includes drawing an imaginary line to pass through the central point of the scanned fingeφrint; calculating direction angles of normal lines at crossing points of the imaginary line and ridges of the fingeφrint; comparing the direction angles of the normal lines of the right ridges of the central point of the scanned fingeφrint with the direction angles of the normal lines of the left ridges of the central point of the scanned fingeφrint; and changing a direction of the imaginary line until an offset value of the direction angles of the normal lines of the right ridges and the left ridges becomes approximate to "0", wherein a direction of a peφendicular line to the finally set imaginary line is decided as a gradient of the scanned fingeφrint when the offset value becomes approximate to "0".
9. The system of claim 5, further comprising, a display panel displaying a text message stored in the memory portion; a voice output portion outputing a voice message stored in the memory portion; a key pad portion including digit keys, letter keys and function keys; and a call portion for calling an inside staff member.
10. A cash dispenser, comprising: a bank card reader determining whether a fingeφrint written on the bank card inserted thereinto is identical to a registered fingerprint or not; a fingeφrint scanning portion scanning a fingeφrint; a memory portion storing the registered fingeφrint; and a controller a) determining a gray level of the scanned fingeφrint image, b) detecting a central point of the scanned fingeφrint image when the quality of the scanned fingeφrint image is acceptable, c) calculating a gradient of the scanned fingeφrint image when the central point the scanned fingeφrint image is located with a designated region, d) determining whether the gradient of the scanned fingeφrint imgae is within an allowable error range, and e) determining whether the scanned fingeφrint is identical to the registered fingeφrint or not when the gradient of the scanned fingeφrint image is within the allowable error range, wherein the cash dispenser operates in response to a control signal output from the controller.
11. The system of claim 10, wherein the step of (a) includes subdividing the scanned fingeφrint into a plurality of blocks; calculating a gray level of each of the plurality of the blocks to determine whether the block is dry or oily; and determining whether the total number of the dry blocks or the total number of the oily blocks is greater than a critical value or not, wherein the fingeφrint is discriminated as unacceptabl when either the total number of the dry blocks or the total number of the oily blocks is greater than the critical value.
12. The system of claim 10, wherien the step of (b) includes designating a boundary region of the central point by calculating a curvature of the scanned fingeφrint image determining whether the central point of the scanned fingeφrint image exists or not; detecting the detecting the central point of the scanned fingeφrint image; and verifying the detected central point of the scanned fingeφrint image using a Poincare index.
13. The system of claim 10, wherein the step of (c) includes drawing an imaginary line to pass through the central point of the scanned fingeφrint; calculating direction angles of normal lines at crossing points of the imaginary line and ridges of the fingeφiϊnt; comparing the direction angles of the normal lines of the right ridges of the central point of the scanned fingeφrint with the direction angles of the normal lines of the left ridges of the central point of the scanned fingeφrint; and changing a direction of the imaginary line until an offset value of the direction angles of the normal lines of the right ridges and the left ridges becomes approximate to "0", wherein a direction of a peφendicular line to the finally set imaginary line is decided as a gradient of the scanned fingeφrint when the offset value becomes approximate to "0".
14. The system of claim 10, further comprising, a display panel displaying a text message stored in the memory portion; a voice output portion outputing a voice message stored in the memory portion; a key pad portion including digit keys, letter keys and function keys; and a call portion for calling a bank clerk.
PCT/KR2001/001798 2000-10-24 2001-10-24 Fingerprint identifying method and security system using the same WO2002035453A1 (en)

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Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
KR10-2000-0062538A KR100409154B1 (en) 2000-10-24 2000-10-24 Real-time fingerprint screening input method
KR2000/62538 2000-10-24
KR2000/30385U 2000-10-31
KR2000/30384U 2000-10-31
KR2020000030385U KR200224845Y1 (en) 2000-10-31 2000-10-31 Automated teller machine of sticking input screening real-time fingerprint
KR2020000030384U KR200219734Y1 (en) 2000-10-31 2000-10-31 Access control installation of induction input screening real-time fingerprint

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