IMAGE PROCESSING APPARATUS, BIOMETRIC AUTHENTICATION APPARATUS, IMAGE PROCESSING METHOD AND RECORDING MEDIUM

• US 20110273554A1
• Filed: 01/21/2010
• Published: 11/10/2011
• Est. Priority Date: 01/22/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Itakura, Yukio, Hoshino, Yukio, Su, Leiming
• Granted Patent: US 9,544,146 B2
• Time in Patent Office: Days
• US Class Current: 348/78
• CPC Class Codes: G06F 21/32 using biometric data, e.g. fingerprints, iris scans or voiceprints
• CPC Class Codes: G06V 40/193 Preprocessing; Feature extraction
• CPC Class Codes: H04L 9/3231 Biological data, e.g. fingerprint, voice or retina network architectures or network communication protocols for supporting authentication of entities using biometrical features in a packet data network H04L63/0861

Abstract

Interlace noises of the image of an iris included in the image of an eye picked up through an interlaced scheme are corrected precisely within a short time. An image processing apparatus (30) corrects a digital image P based on only low-brightness pixels configuring the image of a pupil included in the digital image P of an eye. Accordingly, interlace noises included in the image of the pupil of the eye and that of the iris can be corrected precisely within a short time. Next, a checking apparatus (50) performs authentication on a subject person based on the image of the iris specified based on the corrected digital image P. Hence, precise authentication is enabled.

Claims

1. An image processing apparatus that corrects an image of an eye defined by a plurality of lines belonging to a first line group and a second line group located adjacent to each other, the image being picked up through an interlaced scheme and the image processing apparatus comprising:

a calculating unit which moves the second line group relative to the first line group predetermined amount by predetermined amount, and which calculates, for each pixel belonging to the first line group among pixels configuring an image of a pupil of the eye, a difference in brightness between a pixel belonging to the first line group among pixels configuring the image of the pupil of the eye and a pixel belonging to the second line group and adjacent to the pixel belonging to the first line group;

an integrating unit that integrates brightness differences calculated pixel by pixel; and

a correcting unit that corrects misalignment between the first line group and the second line group based on a relative displacement of the second line group to the first line group when an absolute value of an integrated value obtained by the integrating unit becomes minimum.

2. The image processing apparatus according to claim 1, further comprising an extracting unit that extracts a pixel configuring the image of the pupil based on a reference point included in the image of the pupil of the eye.

3. The image processing apparatus according to claim 2, wherein the reference point is located at a substantial center of the image of the pupil of the eye.

4. The image processing apparatus according to claim 1, wherein the calculating unit detects the difference in brightness using a differential filter for each pixel.

5. The image processing apparatus according to claim 1, wherein the digital image is a binary image.

6. A biometric authentication apparatus that performs authentication using a pattern of an iris, comprising:

an image pickup apparatus that picks up a digital image of an eye;

the image processing apparatus which is according to claim 1 and which executes a correction process on the digital image; and

a processing apparatus that performs biometric authentication using the digital image corrected by the image processing apparatus.

7. An image processing method that corrects a digital image of an eye defined by a plurality of lines belonging to a first line group and a second line group located adjacent to each other, the image being picked up through an interlaced scheme and the image processing method comprising:

a step of moving the second line group relative to the first line group predetermined amount by predetermined amount, and of calculating, for each pixel belonging to the first line group among pixels configuring an image of a pupil of the eye, a difference in brightness between a pixel belonging to the first line group among pixels configuring the image of the pupil of the eye and a pixel belonging to the second line group and adjacent to the pixel belonging to the first line group;

a step of integrating brightness differences calculated pixel by pixel; and

a step of correcting misalignment between the first line group and the second line group based on a relative displacement of the second line group to the first line group when an absolute value of an integrated value of the brightness differences becomes minimum.

8. A computer-readable recording medium storing a program that causes a computer to function as:

a calculating means which moves a second line group relative to a first line group of a digital image of an eye defined by a plurality of lines belonging to the first line group and the second line group located adjacent to each other predetermined amount by predetermined amount, the image being picked up through an interlaced scheme, and which calculates, for each pixel belonging to the first line group among pixels configuring an image of a pupil of the eye, a difference in brightness between a pixel belonging to the first line group among pixels configuring the image of the pupil of the eye and a pixel belonging to the second line group and adjacent to the pixel belonging to the first line group;

an integrating means that integrates brightness differences calculated pixel by pixel; and

a correcting means that corrects misalignment between the first line group and the second line group based on a relative displacement of the second line group to the first line group when an absolute value of an integrated value of the brightness differences becomes minimum.