JPS6143379A - Picture input device - Google Patents

Abstract

PURPOSE:To discriminate automatically an input start timing by starting the collection processing of stripe patterns according to the concentration level of picture signals at positions of picture elements spread over a prescribed two-dimensional area on a picture obtained by a reflected light. CONSTITUTION:A picture pattern of fingerprints obtained from a fingerprint input part 1 is supplied to an input timing processing circuit 2 after photoelectric conversion. The circuit 2 collects the information on the fingerprint patterns in response to the density level of the picture signal and stores a collected pattern information temporarily in a picture memory 3. A collation processor 4 compares the fingerprint feature information given from a file 6 which receives an access by an ID number supplied from a keyboard 5 with the pattern information stored temporarily in the memory 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image input device, and more particularly to an image input device that optically detects a pattern to be verified, such as a fingerprint, and generates an electrical signal.

Conventional systems for identifying individuals using fingerprints use pattern recognition technology to identify the collected fingerprints in order to have high reliability from the beginning due to the characteristics of fingerprints, which are ``unique for all people'' and ``unchangeable throughout life.'' and 1nl- with the fingerprint registered in advance.
Various devices have been proposed to perform gender verification.

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

In such a device, those skilled in the art can easily imagine that the collection of fingerprint images is started by detecting the presence or absence of a finger on the prism using a photodiode or the like installed in the device.
This has the disadvantage that the device and its control are complicated. Furthermore, the image quality of the input fingerprint image tends to vary due to individual sweating, and this quality has a great impact on the later verification process, so it is important to select a good image when collecting the image. is desired.

Purpose of the Invention The present invention has been made to eliminate such conventional drawbacks, and its purpose is to simultaneously detect the placement of a finger on a prism using an image signal from an image display device such as an ITV. An object of the present invention is to provide an image input device that determines the timing for automatically storing an image after determining the 1iLiI quality of a fingerprint image based on a placed fingerprint.

Structure of the Invention The image input device according to the present invention places an object to be inspected having a striped pattern to be checked on the placement surface of a transparent body, and then places the object to be inspected from the side opposite to the object to be inspected. An object to be inspected having a striped pattern to be checked is placed on the placement surface of a transparent body, and incident light is irradiated onto this placement surface from the opposite side of the object to be inspected. An image input device that detects a striped pattern to be checked using reflected light caused by an optical boundary change that occurs on a mounting surface, and in which an object to be inspected is not placed in an image obtained by the reflected light. Sometimes the obtained image has almost no shading distribution, but when it is placed, a shading distribution occurs due to changes in the optical boundary, so stripes are formed depending on the shading level of the image signal at the pixel positions spread on a predetermined two-dimensional plane. It is characterized by forming the IiU beginning of pattern collection processing.

1 凰J The present invention will be explained in detail below using the drawings.

FIG. 1 is a schematic block diagram of a fingerprint matching device to which an embodiment of the present invention is applied, and an image pattern of a fingerprint pattern obtained by inputting to a fingerprint input unit 1 is photoelectrically converted. The image data is temporarily stored in the image memory 3 via the input timing processing circuit 2. On the other hand, the personal identification number (ID number) input from the keyboard 5 is supplied to the collation processor 1-4, and this processor accesses the file 6 using the ID number. Fingerprint characteristic information of each person is stored in advance in the file 6, and the fingerprint characteristic information corresponding to the ID number from the processor is then selectively called up to retrieve the fingerprint stored in the image memory 3. Pattern information and feature comparisons are made.

The above-mentioned prism constituting the fingerprint input section 1 in the device shown in FIG. 1 is shown in FIG. is placed and crimped. The incident light 9 for detection is illuminated from the side opposite to the finger of this face 71, and the reflected light '10 due to the optical boundary change occurring on this face 71 is captured by an iTV camera (not shown). While scanning, it is converted into an 11υ image and converted into an electrical signal.

In this case, it is the input timing processing circuit 2 shown in FIG. 1 that determines the input start timing for fingerprint image collection, and FIG. An example of the arrangement of sample pixels 12 for this purpose is shown. In the resulting image pattern, if no finger is placed, no optical change occurs on the prism surface, but if a finger is placed, an optical change occurs at the interface between the prism surface and the finger. A grayscale distribution is detected between equally sampled pixels.

When detecting the gray level of pixels in an image, synchronization between pixel scanning and measuring the gray level of the scanned pixels is required to check the gray level of all pixels, but the scanning speed is generally high. On the other hand, since the speed of measuring the gray level of a pixel is slow, it is difficult to realize this using a circuit. However, when pixels are sampled radially as shown in FIG. 2(B), there are no pixels adjacent to each other in the pixel scanning direction, so the above problem is solved. A control signal is sent to detect the density levels of a plurality of pixels of the striped pattern 11 obtained here, determine whether or not the finger 8, which is the object to be inspected, is placed on the object based on the level ratio, and start image acquisition. is sent to the input section 1. Upon receiving this signal, the input section 1 stores the fingerprint pattern in the image memory 3.

An example of the arrangement of sample pixels in the second embodiment of the present invention is shown in FIG. 3(A). This is to check the gray level of pixels 13 at regular intervals.In the first embodiment, it is necessary to memorize the coordinates of the pixels 13, but in this embodiment, it is necessary to memorize only the constant interval values. Periodic gray level detection can be performed during scanning.

An example of the arrangement of sample pixels in the third embodiment of the present invention is shown in FIG. 3(B). This is pixel 1 generated by secondary random numbers.
Since a fingerprint is a line figure consisting of many curved lines, the determination result will be affected if the ridges on the fingerprint match or do not match the regularly arranged sample pixels. To solve this problem, the arrangement of the sample pixels is determined randomly. Here, for the same reason as in the first embodiment, when arranging pixels using random numbers, two or more pixels are prevented from being adjacent to each other.

The fourth aspect of the present invention, in which the pixel position interval is made coarser and denser from the periphery to the center of the input screen area, for the purpose of not only detecting the presence or absence of a fingerprint imprint, but also detecting the imprint position and correcting the position of the fingerprint image. An example of the arrangement of sample pixels in Example 6 is shown in the fourth example.
Shown in Figures (A) to (C).

This is because if the stamp is applied to the center of the input image area, the pixels 15 to 17 are dense, so the density distribution is detected, but if the stamp is applied to the periphery, the pixels are coarse, so the density distribution/li
is difficult to detect. Therefore, at this time, appeal to the visual and auditory senses to request reprinting. This method can be easily realized using known methods.

The measurement circuit, comparison circuit, control circuit, etc. for detecting the gray level of the pixel in the above embodiments can be easily implemented by those skilled in the art, and therefore will not be described here. In the above example, the object to be inspected is a human finger print, but
It may also be a projection film for 01-IP on which a fingerprint pattern or other desired patterns to be inspected are printed.

When the scan A7 start command signal is generated and the collection of the entire pattern is started, the user may be notified of the start using an auditory or visual appeal.

Further, even after the input is completed, the input timing processing circuit 2 may similarly notify the user of the completion of the input.

Further, as a result of determination based on the gray level ratio of pixels, image quality can be determined based on the gray level difference on the screen, its distribution, and the like.

In other words, when the difference in density between pixels on the screen is small and the density distribution is small, the image quality is real, so it appeals to the auditory and visual senses and requests re-stamping.

Effects of the Invention According to the present invention, since the input start timing of the object to be inspected is automatically determined, there is an advantage that the user only needs to place the object to be inspected, such as a finger.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of an apparatus to which an embodiment of the present invention is applied, FIG. 2 is a diagram explaining the first embodiment of the present invention, and FIG.
4 and 4 are diagrams showing other embodiments of the present invention, respectively. Explanation of main parts 5'J 1... Fingerprint human input unit 2... Input timing processing circuit 4...
Verification block I Coressa 7... Prism 8... Finger 11... 1j1: White jQ pattern 12-17.
...pixel

Claims (4)

[Claims] (1) An object to be inspected having a striped pattern to be checked is placed on a placement surface of a transparent body, and incident light is irradiated onto this placement surface from the side opposite to the object to be inspected. An image input device that detects a striped pattern to be matched using reflected light due to an optical boundary change caused on the placement surface by light, the image input device detecting a predetermined two-dimensional pattern on an image obtained by the reflected light. An image input device characterized in that the striped pattern sampling process is started in accordance with the gray level of the image signal at the pixel positions that are spread upward. (2) The image input device according to claim 1, wherein the striped pattern sampling process is started in accordance with the gray level of the image signal at pixel positions of pixels at regular intervals on the image. (3) The striped pattern sampling process is started in accordance with the gray level of an image signal at a pixel position generated by a secondary random number on the image. Image input device. (4) The image input device according to any one of claims 1 to 3, characterized in that pixel position intervals are made coarser or denser on the image from the periphery toward the center.