JPH08110949A - Method for judging quality of fingerprint picture - Google Patents
Method for judging quality of fingerprint pictureInfo
- Publication number
- JPH08110949A JPH08110949A JP5131226A JP13122693A JPH08110949A JP H08110949 A JPH08110949 A JP H08110949A JP 5131226 A JP5131226 A JP 5131226A JP 13122693 A JP13122693 A JP 13122693A JP H08110949 A JPH08110949 A JP H08110949A
- Authority
- JP
- Japan
- Prior art keywords
- image
- picture
- area
- quality
- fingerprint
- Prior art date
- Legal status (The legal status 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 status listed.)
- Pending
Links
Landscapes
- Image Analysis (AREA)
- Collating Specific Patterns (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】この発明は、指紋照合等を行う際
の指紋入力画像の画質判定方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the image quality of a fingerprint input image when performing fingerprint collation or the like.
【0002】[0002]
【従来の技術】指紋照合において、入力画像の画質の良
否は照合の精度に非常に大きな影響を与える。例えば、
入力時に指紋面が過度に乾いている場合や、逆に湿って
いる場合は照合精度は劣化する。しかしながら、現在の
ところ、迅速で簡単に入力された指紋画像の画質の良否
を判定する方法は存在しないという問題がある。2. Description of the Related Art In fingerprint matching, the quality of the input image has a great influence on the accuracy of matching. For example,
If the fingerprint surface is excessively dry at the time of input, or if it is wet, the matching accuracy will deteriorate. However, at present, there is a problem that there is no method for determining the quality of a fingerprint image that is input quickly and easily.
【0003】[0003]
【発明が解決しようとする課題】この発明はこのような
従来の問題点を解消すべく創案されたもので、入力され
た画像の画質の良否を判定する指紋画像の画質判定方法
を提供することを目的とする。SUMMARY OF THE INVENTION The present invention was devised to solve such conventional problems, and provides a method for determining the image quality of a fingerprint image for determining the quality of an input image. With the goal.
【0004】[0004]
【課題を解決するための手段】この発明に係る指紋画像
の画質判定方法は、指紋画像を入力して2値化し、この
2値化画像の濃度投影図から重心を求め、この重心を中
心とする所定領域の2値化画像の面積の割合に基づき入
力画像の画質良否判定を行うものである。A fingerprint image quality judging method according to the present invention inputs a fingerprint image, binarizes the fingerprint image, finds a center of gravity from a density projection diagram of the binarized image, and sets the center of gravity as the center of gravity. The image quality of the input image is judged based on the ratio of the area of the binarized image in the predetermined area.
【0005】[0005]
【作用】この発明に係る指紋画像の画質判定方法によれ
ば、指紋画像を入力して2値化し、この2値化画像の濃
度投影図から指紋画像の重心を求めることが可能であ
り、この重心を中心とする所定領域の2値化画像の面積
を求めることが出来る。According to the image quality determination method for a fingerprint image according to the present invention, it is possible to input a fingerprint image, binarize it, and obtain the center of gravity of the fingerprint image from the density projection diagram of this binarized image. It is possible to obtain the area of the binarized image in a predetermined area centered on the center of gravity.
【0006】[0006]
【実施例】次に、この発明に係る指紋画像の画質判定方
法の1実施例を図面に基づいて説明する。図1は本発明
を実施するフローチャート、図6は本発明を実施するた
めの装置のブロック図である。本装置は、例えば中央処
理部CPU、画像処理部IPUおよび画像メモリIMか
ら構成され、中央処理部CPU、画像処理部IPUおよ
び画像メモリIMはシステムバスSBで接続され、さら
に画像メモリIMおよび画像処理部IMはローカルバス
LBでつながれている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of a fingerprint image quality determination method according to the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for carrying out the present invention, and FIG. 6 is a block diagram of an apparatus for carrying out the present invention. The present apparatus is composed of, for example, a central processing unit CPU, an image processing unit IPU and an image memory IM, the central processing unit CPU, the image processing unit IPU and the image memory IM are connected by a system bus SB, and the image memory IM and the image processing IM are further connected. The departments IM are connected by a local bus LB.
【0007】まず検出面に触れている指紋画像を入力装
置(図略)で入力し(ステップ1−1)、この入力画像
を画像メモリIMに登録する(ステップ1−2)。この
画像メモリIMに登録された画像をローカルバスLBを
介して画像処理部IPUに取り込み、2値化処理を施す
(ステップ1−3)。次に、この2値画像を濃度投影し
(ステップ1−4)、濃度投影図を画像メモリIMに登
録する(ステップ1−5)。そして、この濃度投影図に
おけるY軸方向の濃度投影図をYとし、X軸方向の濃度
投影図をXとしてこれら濃度投影図XおよびYの中間値
画素を次の方法で中央処理部CPUで算出して求める
(ステップ1−6)。First, a fingerprint image touching the detection surface is input by an input device (not shown) (step 1-1), and this input image is registered in the image memory IM (step 1-2). The image registered in the image memory IM is taken into the image processing unit IPU via the local bus LB and binarized (step 1-3). Next, this binary image is subjected to density projection (step 1-4), and the density projection diagram is registered in the image memory IM (step 1-5). Then, the density projection diagram in the Y-axis direction in this density projection diagram is defined as Y, and the density projection diagram in the X-axis direction is defined as X, and the intermediate value pixel of these density projection diagrams X and Y is calculated by the central processing unit CPU by the following method. (Step 1-6).
【0008】中央処理部CPUでは、濃度投影図Yの画
素数を数え、X軸に平行にその画素数を数えた場合の中
間値の画素を算出する。また、濃度投影図Xの画素数を
求め、Y軸に平行にその画素数を数えた場合の中間値の
画素を求める。そして、図5に示すように、これら中間
値の画素からY軸、X軸に平行な直線を引いた場合に上
記の2値画像上において交差する点を中央処理部CPU
で算出する(ステップ1−7)。すなわち、これが入力
された指紋2値画像の重心GCである。The central processing unit CPU counts the number of pixels of the density projection diagram Y, and calculates a pixel having an intermediate value when the number of pixels is counted in parallel with the X axis. Further, the number of pixels of the density projection diagram X is obtained, and the pixel having an intermediate value when the number of pixels is counted in parallel with the Y axis is obtained. Then, as shown in FIG. 5, when a straight line parallel to the Y-axis and the X-axis is drawn from the pixel of these intermediate values, the intersection point on the above binary image is determined by the central processing unit CPU.
Is calculated (step 1-7). That is, this is the center of gravity GC of the input binary fingerprint image.
【0009】次に、中央処理部CPUはこの重心GCを
中心とした所定領域(例えば、正方形領域)Aの2値画
像の面積Sを求めて、この2値画像の面積Sが所定領域
Aに占める割合を算出する(ステップ1−8)。Next, the central processing unit CPU obtains the area S of the binary image of a predetermined area (for example, a square area) A with the center of gravity GC as the center, and the area S of this binary image becomes the predetermined area A. The occupied ratio is calculated (step 1-8).
【0010】次に、その割合に基づいて画質の良否判断
を行う(ステップ1−9)。図2に示すように、2値画
像が良好な場合、S/Aの割合は、ほぼ0.4から0.
55であることが経験上判明しており、この両値の間に
納まる2値画像を良画質と判断する(ステップ1−1
0)。Next, the quality of the image quality is judged based on the ratio (step 1-9). As shown in FIG. 2, when the binary image is good, the S / A ratio is approximately 0.4 to 0.
It has been empirically found to be 55, and a binary image that falls between these two values is judged to be of good quality (step 1-1).
0).
【0011】しかしながら、図3に示すように指紋面が
乾きすぎる場合は、指紋パターンが入力されずに隆線部
分の画像の面積が減少する。一方、図4に示すように指
紋面が湿り過ぎる場合は、隆線間のくぼみ部分に湿気が
入り込んでしまい、この部分が隆線部分として取り込ま
れ、2値画像の面積は逆に増加する。このような場合
は、S/Aが適正な割合値から外れてしまい、各々不良
画質と判断する(ステップ1−11)。However, as shown in FIG. 3, when the fingerprint surface is too dry, the fingerprint pattern is not input and the image area of the ridge portion decreases. On the other hand, as shown in FIG. 4, when the fingerprint surface is too wet, moisture enters the dents between the ridges, which are taken in as ridges, and the area of the binary image increases conversely. In such a case, the S / A deviates from the proper ratio value, and each is judged to have a defective image quality (step 1-11).
【0012】このような場合は、入力者に再入力の指示
がなされる(ステップ1−12)。再入力の指示がされ
るとステップ1−2で画像メモリIMに登録された指紋
入力画像は消去される。入力者が指示に従い再入力を行
うと、再入指紋画像が画像メモリIMに登録される。そ
して、ステップ1−9でS/Aが適正範囲に納まり、ス
テップ1−10で良画質と判定されるまで、上記の処理
が繰り返されることになる。In such a case, the input person is instructed to re-input (step 1-12). When a re-input instruction is issued, the fingerprint input image registered in the image memory IM is erased in step 1-2. When the input person performs the re-input according to the instruction, the re-entered fingerprint image is registered in the image memory IM. Then, the above process is repeated until the S / A falls within the proper range in step 1-9 and the image quality is determined to be good in step 1-10.
【0013】[0013]
【発明の効果】以上のように、本発明によれば、指紋画
像を入力して2値化し、この2値化画像の濃度投影図か
ら重心を求め、この重心を中心とする所定領域の2値化
画像の面積の割合に基づき入力画像の画質良否判定を行
うので、迅速かつ簡単な方法で入力指紋画像の画質の良
否判定が可能という効果を有する。これによって、最終
的には適正な入力が実現され、正確な指紋照合が行われ
る。As described above, according to the present invention, a fingerprint image is inputted and binarized, a center of gravity is obtained from a density projection diagram of this binarized image, and a predetermined area centered on the center of gravity Since the image quality of the input image is determined based on the ratio of the area of the binarized image, the quality of the input fingerprint image can be determined quickly and easily. As a result, proper input is finally realized, and accurate fingerprint matching is performed.
【図1】本発明の1実施例を示すフローチャートであ
る。FIG. 1 is a flowchart showing an embodiment of the present invention.
【図2】良画質の例を示す図である。FIG. 2 is a diagram showing an example of good image quality.
【図3】乾きによる不良画質の例を示す図である。FIG. 3 is a diagram showing an example of defective image quality due to drying.
【図4】湿気による不良画質の例を示す図である。FIG. 4 is a diagram showing an example of defective image quality due to moisture.
【図5】2値の指紋画像と濃度投影図を示す図である。FIG. 5 is a diagram showing a binary fingerprint image and a density projection diagram.
【図6】本発明を実施する装置のブロック図である。FIG. 6 is a block diagram of an apparatus for implementing the present invention.
CPU 中央処理部 IPU 画像処理部 IM 画像メモリ SB システムバス LB ローカルバス A 所定領域 CPU central processing unit IPU image processing unit IM image memory SB system bus LB local bus A predetermined area
Claims (1)
化し、この2値化画像の濃度投影図から指紋画像の重心
を求め、この重心を中心とする所定領域の前述の2値化
画像の面積を求め、この面積の割合に基づき入力画像の
良否判定を行うことを特徴とする指紋画像の画質判定方
法。1. A fingerprint image is input, the input image is binarized, the center of gravity of the fingerprint image is obtained from a density projection diagram of the binarized image, and the binarization of a predetermined area centered on the center of gravity is performed. A method for determining the image quality of a fingerprint image, which comprises determining the area of an image and determining the quality of the input image based on the ratio of the area.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5131226A JPH08110949A (en) | 1993-05-07 | 1993-05-07 | Method for judging quality of fingerprint picture |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5131226A JPH08110949A (en) | 1993-05-07 | 1993-05-07 | Method for judging quality of fingerprint picture |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH08110949A true JPH08110949A (en) | 1996-04-30 |
Family
ID=15052981
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP5131226A Pending JPH08110949A (en) | 1993-05-07 | 1993-05-07 | Method for judging quality of fingerprint picture |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH08110949A (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1349106A1 (en) * | 2002-03-27 | 2003-10-01 | Fujitsu Limited | Finger movement detection method and apparatus |
WO2004077366A1 (en) * | 2003-02-28 | 2004-09-10 | Kabushiki Kaisha Nippon Conlux | Sheet identifying device and method |
WO2004079658A1 (en) * | 2003-03-07 | 2004-09-16 | Nippon Telegraph And Telephone Corporation | Biological image correlation device and correlation method thereof |
US7079672B2 (en) | 2000-01-28 | 2006-07-18 | Chuo Hatsujo Kabushiki Kaisha | Fingerprint image evaluating method and fingerprint matching device |
US7272249B2 (en) | 2002-09-27 | 2007-09-18 | Nec Corporation | Fingerprint authentication method, program and device capable of judging inexpensively whether input image is proper or not |
US7330572B2 (en) | 2002-09-27 | 2008-02-12 | Nec Corporation | Fingerprint authentication method, program and device capable of judging inexpensively whether input image is proper or not |
US7769206B2 (en) | 2004-03-04 | 2010-08-03 | Nec Corporation | Finger/palm print image processing system and finger/palm print image processing method |
WO2022172487A1 (en) * | 2021-02-10 | 2022-08-18 | シャープ株式会社 | Electronic device, control device, control method, and control program |
-
1993
- 1993-05-07 JP JP5131226A patent/JPH08110949A/en active Pending
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7079672B2 (en) | 2000-01-28 | 2006-07-18 | Chuo Hatsujo Kabushiki Kaisha | Fingerprint image evaluating method and fingerprint matching device |
EP1349106A1 (en) * | 2002-03-27 | 2003-10-01 | Fujitsu Limited | Finger movement detection method and apparatus |
US7272249B2 (en) | 2002-09-27 | 2007-09-18 | Nec Corporation | Fingerprint authentication method, program and device capable of judging inexpensively whether input image is proper or not |
US7330572B2 (en) | 2002-09-27 | 2008-02-12 | Nec Corporation | Fingerprint authentication method, program and device capable of judging inexpensively whether input image is proper or not |
WO2004077366A1 (en) * | 2003-02-28 | 2004-09-10 | Kabushiki Kaisha Nippon Conlux | Sheet identifying device and method |
GB2417773A (en) * | 2003-02-28 | 2006-03-08 | Nippon Conlux Co Ltd | Sheet identifying device and method |
WO2004079658A1 (en) * | 2003-03-07 | 2004-09-16 | Nippon Telegraph And Telephone Corporation | Biological image correlation device and correlation method thereof |
CN100397421C (en) * | 2003-03-07 | 2008-06-25 | 日本电信电话株式会社 | Biological image correlation device and correlation method thereof |
US7673145B2 (en) | 2003-03-07 | 2010-03-02 | Nippon Telephone And Telegraph Corporation | Biometric image collation apparatus and collation method therefor |
US7769206B2 (en) | 2004-03-04 | 2010-08-03 | Nec Corporation | Finger/palm print image processing system and finger/palm print image processing method |
WO2022172487A1 (en) * | 2021-02-10 | 2022-08-18 | シャープ株式会社 | Electronic device, control device, control method, and control program |
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