JPS6159582A - Pattern center position determining device - Google Patents

Abstract

PURPOSE:To determine a central line position of a line pattern automatically by scanning an input line pattern, obtaining run length information which is a series of an about constant density of respective scanning lines and calculating a run length and appearance frequency. CONSTITUTION:An inputted fingerprint is scanned at an input part 1, digitized and stored in a pattern memory 4. By an ID number inputted from a keyboard 2, a file 6m, in which characteristic information o plural fingerprints is stored beforehand, is accessed, special fingerprint characteristic information is read and sent to a collating part 5. At the collating part 5, fingerprint characteristics from the memory 4 are extracted, and compared with information from the file 6. On the other hand, run length information from a scanning line obtained at the input part 1, is detected at a run length detecting part 7 and stored for respective scanning lines at a memory 8. These pieces of run length information are compare;d at a comparing part 9 and the central line is determined. It is judged at a pattern center coincidence judging part 10 whether or not the central scanning line is coincident with the central line obtained at the comparing part 9, and when it is not coincident, it is required to take a fingerprint again.

Description

TECHNICAL FIELD The present invention relates to a graphic center position determining device, and more particularly to a graphic center position determining device for determining the graphic center position of a curved graphic pattern such as a fingerprint.

Conventional systems that use fingerprints to identify individuals have extremely high reliability due to the characteristics of fingerprints, which are "unique for everyone" and "unchangeable throughout life." Various devices have been proposed that perform identity verification with fingerprints registered in advance.

In such a fingerprint verification device, a fingerprint pattern is generated from the back side of the placement surface of a finger placed on the finger device surface of a glass prism using a light source and an imaging device such as an ITV, using the optical boundary conditions of the glass. It has a fingerprint input device that generates a photoelectric conversion image, and is disclosed, for example, in Japanese Patent Application Laid-Open No. 54-69300 and Japanese Patent Application Publication No. 54-85600.

In such a device, whether or not the input fingerprint can be identified by comparing and collating the characteristics of the input fingerprint pattern with one of the fingerprint pattern characteristic information in a plurality of files stored in advance in the storage means. The individual is identified by determining the identity of the person. Therefore, it is necessary to accurately capture the image pattern of the input fingerprint pattern in order to ensure accuracy in feature extraction and verification processing. In particular, if the center line of the image pattern coincides with the central scanning line of the image scanning section of the photoelectric conversion section, then almost the entire fingerprint pattern will be collected, and it will be possible to obtain the image on this pattern. This is desirable because it increases the number of feature points and improves the performance of matching based on the features in the registered file. If these two center lines match, the entire fingerprint pattern is detected by scanning and converted into an electrical signal.
If the two center lines shift, part of the fingerprint pattern will not be scanned, making it difficult to detect a complete fingerprint pattern.

Therefore, a device that automatically determines the center position of the fingerprint pattern is needed, but as a conventional example,
No. 5548 and No. 58-55549, both of which are disclosed, have a very m9a configuration.

OBJECTS OF THE INVENTION An object of the present invention is to provide a graphic center position determination device with a simple configuration that can automatically determine the center line position of a linear graphic pattern such as a fingerprint, which is composed of a plurality of curved lines.

Composition of the Invention The figure center position determining device according to the present invention is a device for determining the center line position of a line figure consisting of a plurality of curves in which curves are sequentially arranged outside one curve, and which determines the center line position of a line figure having a line figure. an input section that optically scans the line pattern to quantize the line pattern; and obtains run length information, which is a series of approximately constant density according to the curve on each scanning line obtained by scanning the line pattern; The present invention is characterized by having a run length detection unit that calculates each run length length and its appearance frequency for each scanning line based on the length information, and a center line determination unit that determines the center line position of the line figure based on the calculation result. .

Example The present invention will be explained in detail below using the drawings.

FIG. 1 and FIG. 2 are diagrams for explaining the present invention in detail,
The direction perpendicular to the longitudinal direction of the fingerprint pattern (indicated by diagonal lines) (a-
When pattern scanning is performed in the horizontal scanning line direction indicated by C), the run length of the series (run) of light and dark (in this case, black) levels obtained by the signals from each scanning line a-C and its frequency of appearance. When , respectively, are determined, it can be seen that the results are as shown in FIGS. 2(a) to (C).

Note that the fingerprint ridges are indicated by black diagonal lines), and the background part is indicated by white lines.

What we can learn from this is that in the case of the fingerprint pattern shown in Figure 1, the run length, that is, the scanning line where the length is small and where the black level of this small length appears frequently is close to the center line position of the fingerprint pattern. It becomes. Therefore, by measuring and determining the length of a run, which is a series of black level signals, and its appearance frequency for each scanning line, it becomes possible to determine the position of the pattern center line.

Based on this fact, the block shown in FIG. 3 is obtained. In the figure, 1 is an input unit for optically scanning and inputting a fingerprint pattern, 2 is a keyboard for inputting an ID (personal identification) number, and 3 is for controlling this input unit 1 and other devices. This is the control section. The input fingerprint is input part 1
The pattern is scanned, converted into an electrical signal, digitized, and partially stored in the pattern memory 4. The file 6 is accessed by the number 10 entered from the keyboard 2, but characteristic information of a plurality of fingerprints is stored in advance in this file 6, and the fingerprint characteristic information specified by the D number is read out. The data is then derived to the collation unit 5. Therefore, the fingerprint characteristics of the pattern stored in the memory 4 are extracted in the verification section 5 and compared with the information from the file 6.

On the other hand, run length information from the scanning line obtained by the input section 1 is detected by the run length detection section 7. This information includes the length of a run, which is a series of black levels, and its appearance frequency, and is stored in the storage unit 8 for each scanning line. These run length information are compared in units of scanning lines by a comparing section to determine the center line. and,
The figure center coincidence determination unit 10 determines whether or not the center scanning line of the scanning lines matches the center line determined by the comparison unit 9.
If the fingerprints do not match, a non-coincidence signal is fed back to the control unit 2 and the user is requested to reprint the fingerprint using a known visual or auditory method. Here, each component can be easily constructed by a person skilled in the art, and the details thereof will be omitted. Also, a known method will be used for the verification method.

FIG. 4 is a flowchart illustrating the operation of the apparatus shown in FIG. 3. When an ID number is input and a fingerprint is affixed, image scanning is started and run length information is detected for each scanning line. The run length value and frequency of appearance are detected from this information, and whether or not the figure center line and the scanning center line match is determined based on the correlation between the run length value and the frequency of appearance.

If there is a mismatch, the user is requested to stamp again and the same process is executed again. When the figure center line and the scanning center line substantially match in this way, the fingerprint verification process is started for the first time.

Note that a known method is used to determine whether or not a fingerprint has been imprinted by processing an input image using a photodiode or the like.

Effects of the Invention According to the present invention, it is possible to automatically determine the center line position of a line figure with a simple configuration, so that the center position of the line figure to be detected can be controlled to be set at the scanning center. This has the advantage that the entire graphic pattern can be obtained accurately.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between graphic patterns and scanning lines for detailed explanation of the present invention, and FIG. 2 is a diagram showing the run length of a run obtained by each scanning line in the image pattern of FIG. 1 and its appearance. FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a flowchart showing the operation of the blocks in FIG. 3. Explanation of symbols of main parts 1... Input section 3... Control section

Claims (1)

[Claims] A device for determining the center line position of a line figure consisting of a plurality of curves in which curves are sequentially arranged outside one curve, the apparatus optically scanning an object having a line figure to determine the line figure. an input section for quantization; while scanning the line figure, obtaining run length information that is a series of approximately constant density according to the curve on each scan line; and using this run length information, each run length length and its appearance frequency are determined for each scan; A figure center position determination device comprising: a run length detection unit that calculates for each line; and a center position determination unit that determines the center line position of the line figure based on the calculation result.