Biometric image processing apparatus and biometric image processing method

• US 10,303,917 B2
• Filed: 03/13/2017
• Issued: 05/28/2019
• Est. Priority Date: 03/25/2016
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hama, Soichi, Semba, Satoshi
• Primary Examiner(s): Akhavannik, Hadi
• Application Number:
  US15/457,440
• Publication Number:
  US 20170277934A1
• Time in Patent Office: 806 Days
• Field of Search: None
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: G06V 40/14 Vascular patterns
• CPC Class Codes: G06V 40/145 Sensors therefor

Abstract

A biometric image processing apparatus includes an imaging device that captures a first image of a biometric part that is irradiated with light having a first wavelength, and a second image of the biometric part irradiated with light having a second wavelength shorter than the first wavelength, and a computing device that computes a third image by subtracting from the first image an image in which a luminance of the second image is attenuated.

Claims

1. A biometric image processing apparatus comprising:

an imaging device configured to capture a first image of a biometric part that is irradiated with light having a first wavelength, and a second image of the biometric part irradiated with light having a second wavelength shorter than the first wavelength; and

a computing device configured to attenuate a luminance of the second image by an attenuation rate, and compute a third image by subtracting, from the first image, the second image having the luminance attenuated by the attenuation rate,

wherein the attenuation rate of the second image is determined according to an intensity of a component of surface reflection light included in the first image.

2. The biometric image processing apparatus as claimed in claim 1, wherein

the computing device determines the attenuation rate of the second image according to the intensity of the component of surface reflection light included in the first image,

the first wavelength is longer than 600 nm, and the second wavelength is 600 nm or shorter, and

the third image is a vein image.

3. The biometric image processing apparatus as claimed in claim 1, further comprising:

a light source configured to irradiate, on the biometric part, light having wavelengths including the first wavelength and the second wavelength; and

a separator configured to separate returning light from the biometric part into a first component having the first wavelength and a second component having the second wavelength,

wherein the imaging device includes a first camera configured to capture the first image based on the first component separated by the separator, and a second camera configured to capture the second image based on the second component separated by the separator.

4. The biometric image processing apparatus as claimed in claim 3, wherein the separator includes

a prism configured to receive the returning light from the biometric part,

a first optical wavelength filter configured to transmit the first component of the returning light separated by the prism, and

a second optical wavelength filter configured to transmit the second component of the returning light separated by the prism,

wherein the first camera and the second camera are arranged so that optical axes thereof match.

5. The biometric image processing apparatus as claimed in claim 1, further comprising:

a light source configured to irradiate, on the biometric part, light having wavelengths including the first wavelength and the second wavelength;

a first filter configured to transmit a first component having the first wavelength and to cut a second component having the second wavelength, of returning light from the biometric part; and

a second filter configured to transmit the second component and to cut the first component, of the returning light from the biometric part,

wherein the imaging device includes a camera configured to capture the first image based on the first component transmitted through the first filter, and to capture the second image based on the second component transmitted through the second filter.

6. The biometric image processing apparatus as claimed in claim 5, further comprising:

an RGB filter that includes the first filter and the second filter.

7. The biometric image processing apparatus as claimed in claim 1, further comprising:

a first light source configured to irradiate the biometric part with light having the first wavelength;

a second light source configured to irradiate the biometric part with light having the second wavelength; and

a controller configured to alternately turn on the first light source and the second light source,

wherein the imaging device captures the first image based on a component having the first wavelength of the returning light from the biometric part, while the controller turns on the first light source, and captures the second image based on a component having the second wavelength of the returning light from the biometric part while the controller turns on the second light source.

8. The biometric image processing apparatus as claimed in claim 1, further comprising:

a first light source configured to irradiate the biometric part with light having the first wavelength;

a second light source configured to irradiate the biometric part with light having the second wavelength;

a first filter configured to transmit a first component having the first wavelength and to cut a second component having the second wavelength, of returning light from the biometric part; and

a second filter configured to transmit the second component and to cut the first component, of the returning light from the biometric part,

wherein the imaging device includes a camera configured to capture the first image based on the first component transmitted through the first filter, and to capture the second image based on the second component transmitted through the second filter.

9. The biometric image processing apparatus as claimed in claim 8, further comprising:

an RGB filter that includes the first filter and the second filter.

10. The biometric image processing apparatus as claimed in claim 1, wherein the computing device normalizes a luminance level of the second image according to a luminance level of the first image.

20. The biometric image processing apparatus as claimed in claim 1, wherein the computing device computes the third image according to a formula I_v=I_lw−

κ

·

I_sw, where I_v denotes the third image, I_lw denotes the first image, I_sw denotes the second image, and κ

denotes a coefficient that is less than 1 and represents the attenuation rate of the luminance of the second image I_sw caused by the light having the second wavelength, determined according to an intensity of a component of surface reflection light included in the first image I_lw caused by the light having the first wavelength.

11. A biometric image processing method comprising:

capturing, by an imaging device, a first image of a biometric part that is irradiated with light having a first wavelength, and a second image of the biometric part irradiated with light having a second wavelength shorter than the first wavelength; and

computing, by a computing device, the second image having a luminance thereof attenuated by an attenuation rate, and a third image by subtracting, from the first image, the second image having the luminance attenuated by the attenuation rate,

wherein the attenuation rate of the second image is determined according to an intensity of a component of surface reflection light included in the first image.

12. The biometric image processing method as claimed in claim 11, wherein

the computing determines, by the computing device, the attenuation rate of the second image according to the intensity of the component of surface reflection light included in the first image,

the first wavelength is longer than 600 nm, and the second wavelength is 600 nm or shorter, and

the third image is a vein image.

13. The biometric image processing method as claimed in claim 11, further comprising:

irradiating on the biometric part, by a light source, light having wavelengths including the first wavelength and the second wavelength; and

separating, by a separator, returning light from the biometric part into a first component having the first wavelength and a second component having the second wavelength,

wherein the capturing captures the first image by a first camera of the imaging device based on the first component separated by the separating, and captures the second image by a second camera of the imaging device based on the second component separated by the separating.

14. The biometric image processing method as claimed in claim 11, further comprising:

irradiating on the biometric part, by a light source, light having wavelengths including the first wavelength and the second wavelength;

of returning light from the biometric part, transmitting a first component having the first wavelength and cutting a second component having the second wavelength, by a first filter; and

of the returning light from the biometric part, transmitting the second component and cutting the first component, by a second filter,

wherein the capturing captures, by a camera of the imaging device, the first image based on the first component transmitted through the first filter, and the second image based on the second component transmitted through the second filter.

15. The biometric image processing method as claimed in claim 14, which uses an RGB filter that includes the first filter and the second filter.

16. The biometric image processing method as claimed in claim 11, further comprising:

irradiating the biometric part, by a first light source, with light having the first wavelength;

irradiating the biometric part, by a second light source, with light having the second wavelength; and

controlling, by a controller, the first light source and the second light source to alternately turn on the first light source and the second light source,

wherein the capturing captures, by a camera of the imaging device, the first image based on a component having the first wavelength of the returning light from the biometric part, while the controller turns on the first light source, and the second image based on a component having the second wavelength of the returning light from the biometric part while the controller turns on the second light source.

17. The biometric image processing method as claimed in claim 11, further comprising:

irradiating the biometric part, by a first light source, with light having the first wavelength;

irradiating the biometric part, by a second light source, with light having the second wavelength;

of returning light from the biometric part, transmitting a first component having the first wavelength and cutting a second component having the second wavelength, by a first filter; and

of the returning light from the biometric part, transmitting the second component and cutting the first component, by a second filter,

wherein the capturing captures, by a camera of the imaging device, the first image based on the first component transmitted through the first filter, and the second image based on the second component transmitted through the second filter.

18. The biometric image processing method as claimed in claim 17, which uses an RGB filter that includes the first filter and the second filter.

19. The biometric image processing method as claimed in claim 11, wherein the computing includes normalizing, by the computing device, a luminance level of the second image according to a luminance level of the first image.