OPTICAL FINGERPRINT SENSOR WITH SCATTERED LIGHT IMAGE DETECTION

• US 20190012507A1
• Filed: 07/06/2017
• Published: 01/10/2019
• Est. Priority Date: 07/06/2017
• Status: Active Grant

• Current Assignee: Fingerprint Cards IP AB
• Original Assignee: Synaptics Incorporated
• Inventors: Dattalo, Scott
• Granted Patent: US 10,354,116 B2
• Time in Patent Office: Days
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: G06V 40/1376 Matching features related to ridge properties or fingerprint texture

Abstract

A method and apparatus for authenticating a fingerprint image captured through an optical sensor. For at least some embodiments, light scattering characteristics associated with a fingerprint are determined and compared to a reference light scattering characteristic. The fingerprint is authenticated when the light scattering characteristics are within a threshold difference of the reference light scattering characteristic. For some embodiments, the light scattering characteristics associated with the fingerprint are compared to light scattering characteristics associated with one or more reference (enrollment) images. For at least some embodiments, the light scattering characteristics may be based on a correlation value based on identified pixels and one or more pixels neighboring the identified pixel.

Claims

1. A method for authenticating an input object, comprising:

determining a light scattering characteristic of the input object;

comparing the determined light scattering characteristic with a reference light scattering characteristic to determine an authentication status of the input object; and

generating a validation signal indicating the authentication status of the input object.

2. The method of claim 1, wherein determining the light scattering characteristic of the input object comprises:

receiving image data associated with the input object;

identifying at least one of a ridge pixel or a valley pixel within the image data; and

determining a first metric of scattered light based on differences in pixel values between the identified pixel within the image data and one or more pixels neighboring the identified pixel wherein the first metric of scattered light is at least one light scattering characteristic of the input object.

3. The method of claim 2, wherein the one or more pixels neighboring the identified pixel are not separated from the identified pixel by any number of pixels.

4. The method of claim 2, further comprising:

receiving image data associated with a plurality of images;

identifying at least one of a ridge pixel or a valley pixel within the image data associated with the plurality of images; and

determining a second metric of scattered light based on differences in pixel values between the identified pixel associated with the plurality of images and one or more pixels neighboring the identified pixel.

5. The method of claim 4, further comprising:

comparing the first metric of scattered light with the second metric of scattered light to determine the authentication status of the input object; and

generating the validation signal indicating the authentication status of the input object.

6. The method of claim 4, wherein determining the second metric of scattered light comprises:

determining a first correlation value of ridge pixels associated with each image in the plurality of images; and

determining a second correlation value of valley pixels associated with each image in the plurality of images, wherein the second metric of scattered light is based on at least one of the first correlation value or the second correlation value.

7. The method of claim 6, further comprising:

determining aggregate correlation values associated with ridge pixels of each image in the plurality of images to determine the first correlation value; and

determining aggregate correlation values associated with valley pixels of each image in the plurality of images to determine the second correlation value.

8. The method of claim 4, wherein the at least one ridge pixel or valley pixel is identified based on one or more reference images associated with the plurality of images.

9. The method of claim 8, further comprising:

determining a first reference image based on an aggregate of pixel values across the plurality of images; and

determining a second reference image based on a deviation of pixel values across the plurality of images.

10. An input device, comprising:

an optical sensor configured to receive scattered light from an input object;

a processing system coupled to the optical sensor and configured to;

determine a light scattering characteristic of the input object;

compare the determined light scattering characteristic with a reference light scattering characteristic to determine an authentication status of the input object; and

generate a validation signal indicating the authentication status of the input object.

11. The input device of claim 10, wherein the processing system is further configured to:

receive image data associated with the input object;

identify at least one of a ridge pixel or a valley pixel within the image data; and

determine a first metric of scattered light based on differences in pixel values between the identified pixel within the image data and one or more pixels neighboring the identified pixel, wherein the first metric of scattered light is at least one light scattering characteristic of the input object.

12. The input device of claim 11, wherein the one or more pixels neighboring the identified pixels are not separated from the identified pixel by any number of pixel.

13. The input device of claim 11, wherein the processing system is further configured to:

receive image data associated with a plurality of images;

identify at least one of a ridge pixel or a valley pixel within the image data associated with the plurality of images; and

determine a second metric of scattered light based on differences in pixel values between the identified pixel associated with the plurality of images and one or more pixels neighboring the identified pixel.

14. The input device of claim 13, wherein the processing system is further configured to:

compare the first metric of scattered light with the second metric of scattered light to determine the authentication status of the input object; and

generate the validation signal indicating the authentication status of the input object.

15. The input device of claim 13, wherein the processing system is further configured to:

determine a first correlation value of ridge pixels associated with each image in the plurality of images; and

determine a second correlation value of valley pixels associated with each image in the plurality of images, wherein the second metric of scattered light is based on at least one of the first correlation value or the second correlation value.

16. The input device of claim 15, wherein the processing system is further configured to:

aggregate correlation values associated with ridge pixels of each image in the plurality of images to determine the first correlation value; and

aggregate correlation values associated with valley pixels of each image in the plurality of images to determine the second correlation value.

17. The input device of claim 13, wherein the at least one ridge pixel or valley pixel is identified based on one or more reference images associated with the plurality of images.

18. The input device of claim 17, wherein the processing system is further configured to:

determine a first reference image based on an aggregate of pixel values across the plurality of images; and

determine a second reference image based on a deviation of pixel values across the plurality of images.

19. A non-transitory computer-readable storage medium storing instructions that, when executed by one or more processors of a device, cause the device to:

determine a light scattering characteristic of an input object;

compare the determined light scattering characteristic with a reference light scattering characteristic to determine an authentication status of the input object; and

generate a validation signal indicating the authentication status of the input object.

20. The non-transitory computer-readable storage medium of claim 19, wherein execution of the instructions causes the device to further:

receive image data associated with the input object;

identify at least one of a ridge pixel or a valley pixel within the image data; and

determine a first metric of scattered light based on differences in pixel values between the identified pixel within the image data and one or more pixels neighboring the identified pixel, wherein the first metric of scattered light is at least one light scattering characteristic of the input object.