Image analysis – Applications – Personnel identification
Reexamination Certificate
1998-01-23
2001-01-16
Mehta, Bhavesh (Department: 2721)
Image analysis
Applications
Personnel identification
C382S209000, C382S218000
Reexamination Certificate
active
06175640
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image collation apparatus, and more particularly to a fingerprint comparing apparatus.
2. Description of the Related Art
Heretofore, in the conventional fingerprint comparing apparatus using an image collation apparatus of this sort, feature points such as a branch, point and cut (hereinafter referred to as “feature point(s)”) are extracted from a fingerprint image obtained by means of an image pick-up device, and fingerprint collation is performed with reference to these feature points.
In other words, in the conventional fingerprint collation device, a fingerprint to be collated is incorporated in advance into a database with reference to, for example, feature points and their coordinates. A fingerprint image to be collated is subjected to image processing to extract feature points. Then, the database is accessed with reference to the extracted featured points, and the fingerprint is collated according to the existence or absence of corresponding feature points.
The conventional way of fingerprint collation has the disadvantage that the processing takes a long time. If finger collation can be carried out reliably in a short period of time, the fingerprint collation apparatus can become more convenient and useful.
A conceivable solution to this problem is to cut a linear image out of the fingerprint to be collated, and displace the cut-out linear image sequentially over the reference fingerprint image which has been incorporated into a database to detect the result of comparison. This method, however, takes a long time to process the detected result of comparison, and accordingly involves inadequacy in practical use.
The present invention has been undertaken in view of these problems, and is intended to propose an image collating apparatus which is capable of judging simply and reliably whether or not a given image of fingerprint or the like coincides with a reference image.
SUMMARY OF THE INVENTION
To solve these problems, according to the invention, a plurality of areas cut out of a first image are sequentially displaced over a second image, the degree of coincidence between each area and the second image is sequentially detected with reference to coordinates of the second image, and the distribution of the degrees of coincidence is thereby detected for each area. Then, the coordinates of the distribution of the degrees of coincidence are corrected with the relative positions of a plurality of areas to sum up the distributions of the degrees of coincidence, and whether or not the first image is coincident with the second image is judged from the peak value of this total of the distributions.
As the areas cut out of the first image are sequentially displaced over the second image and the degree of coincidence between each area and the second image is sequentially detected with reference to coordinates of the second image, if the first and second images should essentially coincide with each other, a high degree of coincidence will be detected in each pair of counterpart positions. Elsewhere than pairs of counterpart positions, and even where the first and second images differ from each other, parts of high degrees of coincidence may be detected.
If, with respect to the distribution of the degrees of coincidence prepared from the degrees of coincidence detected in this manner with reference to the coordinates of each pixel of the second image, the coordinates are corrected with the relative positions of a plurality of areas to sum up the distributions of the degrees of coincidence, and if the first and second images should essentially coincide with each other, high degrees of coincidence will be sequentially added in each area for coordinates satisfying the relative positional requirements of the plurality of areas, and high peak values will be detected. Conversely, if the first and second images are different, it will be difficult to detect high peak values either for coordinates satisfying the relative positional requirements of the plurality of areas or for coordinates satisfying no relative positional requirements.
This disposition makes it possible to judge whether or not the image collated is coincident with the reference image according to this peak value, and pass a reliable judgment. The distributions of the degrees of coincidence can be summed up by the easy processing of cumulatively adding the distributions of the degrees of coincidence stored in a memory.
REFERENCES:
patent: 4057845 (1977-11-01), Ejiri et al.
patent: 4334241 (1982-06-01), Kashioka et al.
patent: 5177792 (1993-01-01), Morita
patent: 5568564 (1996-10-01), Ozaki
Kananen Ronald P.
Mehta Bhavesh
Rader Fishman & Grauer
Sony Corporation
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