Image analysis – Applications – Personnel identification
Patent
1995-09-29
1998-07-28
Mancuso, Joseph
Image analysis
Applications
Personnel identification
382275, G06K 900
Patent
active
057871850
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/GB94/00707 filed Mar. 31, 1994.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the biometric identification of individuals and, in particular, to methods and apparatus for detecting the locations of subcutaneous blood vessels and for encoding such locations for storage on identity cards. It finds particular application in the verification of identity in transactions involving such cards.
In this specification, the expression "vein pattern" is deemed to include the pattern of arteries, capillaries and other blood vessels.
2. Description of the Related Art
In British Patent No. 2156127 there is described a method and apparatus for the identification of individuals by means of subcutaneous patterns of blood vessels. One difficulty encountered with such apparatus is the poor signal-to-noise ratio when endeavouring to detect blood vessel locations, for example, in the back of the hand. This may be due to hairs, or the non-planar nature of the locations or uneven illumination.
SUMMARY OF THE INVENTION
We have now devised an improved method of verifying the identity of individuals. According to the present invention there is provided a method of verifying the identity of an individual comprising the steps of capturing an image of the subcutaneous vein pattern at a predetermined region of the individual, converting said captured image to a plurality of stored values representative of the intensity of said image at specified relative locations, processing said stored values to produce a second plurality of stored values representative of an image of said vein pattern having enhanced contrast and subjecting said second plurality of stored values to a thresholding process to select those above a predetermined value and storing a set of measurements derived from the selected ones of said second plurality of stored values for comparison with a corresponding set of measurements made on said individual.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be particularly described with reference to the accompanying drawings, in which:-
FIG. 1 is a perspective view of apparatus suitable for scanning vein patterns;
FIG. 2 is a block diagram of apparatus in accordance with a preferred embodiment of the invention;
FIG. 3 shows a raw vein pattern obtained from the apparatus of FIG. 2;
FIG. 4 shows the image of FIG. 3 after processing to enhance its contrast;
FIG. 5 shows the image of FIG. 4 after processing to reveal boundary lines;
FIG. 6 shows a pattern of vectors imposed on the image of FIG. 5;
FIG. 7 shows two superimposed vein patterns;
FIG. 8 shows the vein patterns after alignment;
FIG. 9 shows the matched portions of the two superimposed patterns; and
FIG. 10 shows the mismatched portions of the vein patterns.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, a hand 1 of an individual whose identity is to be verified is positioned approximately by gripping a positional reference handle 3. An optional side stop 5, against which the side of the hand abuts, provides an additional constraint. Even illumination is provided by four laterally-positioned incandescent lamps 7,9,11,13 which are under-run to provide an infra-red-rich emission spectrum. A video camera 15 is positioned directly above the hand position and produces a raster-scan image of the back of the hand. A band-pass filter 17 extracts an infra-red image and reduces the proportion of visible radiation. It therefore enhances the visibility of the subcutaneous vein pattern.
By viewing the vein pattern through a pair of filters having different transmission characteristics, it is possible to differentiate between veins and arteries, which have different relative contents of oxy-haemoglobin and carboxy-haemoglobin. This may be used as a basis for enhanced recognition tests or simply to verify that the hand is still attached and vital.
The two images may be obtained sequentially by substituting one filter for the other or simultaneously
REFERENCES:
patent: 4550437 (1985-10-01), Kobayashi et al.
patent: 4571635 (1986-02-01), Mahmoodi et al.
patent: 4699149 (1987-10-01), Rice
patent: 4811414 (1989-03-01), Fishbine et al.
patent: 5003618 (1991-03-01), Meno
British Technology Group Ltd.
Mancuso Joseph
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