Eye tracking

Patent metadata

Field	Value
Publication number	US-2016196465-A1
Application number	US-201514591865-A
Country	US
Kind code	A1
Filing date	Jan 7, 2015
Priority date	Jan 7, 2015
Publication date	Jul 7, 2016
Grant date	—

Abstract

Examples are disclosed herein that relate to eye tracking based on two-dimensional image data. One example provides, on a computing device, a method of tracking an eye. The method includes receiving image data from an image sensor, detecting a face of the user in the image data, locating the eye in a region of the face in the image data to obtain an eye image, normalizing one or more of a scale and an illumination of the eye image, fitting an ellipse to an iris of the eye in the eye image, and outputting a determination of an eye gaze direction based upon the ellipse fitted.

First claim

1 . On a computing device, a method of tracking an eye, the method comprising:
receiving image data from an image sensor; detecting a face of the user in the image data; locating the eye in a region of the face in the image data to obtain an eye image; normalizing one or more of a scale and an illumination of the eye image; fitting an ellipse to an iris of the eye in the eye image; and outputting a determination of an eye gaze direction based upon the ellipse fitted.

2 . The method of claim 1 , wherein normalizing the scale of the eye image comprises scaling the eye image to normalize a distance between features in the eye image.

3 . The method of claim 1 , wherein normalizing the illumination of the eye image comprises forming a gray scale image from the eye image and normalizing intensity of the grayscale image.

4 . The method of claim 1 , further comprising performing segmentation on the image data to mask out one or more of a non-eye area and a non-iris area of the eye image prior to fitting the ellipse.

5 . The method of claim 1 , wherein fitting the ellipse to the iris comprises applying a plurality of ellipse hypotheses to the image data, and determining for each ellipse hypothesis a voting map corresponding to the eye image.

6 . The method of claim 5 , wherein fitting the ellipse comprises, for each pixel of the eye image, determining a gradient vector for the pixel, and updating a value of a corresponding pixel of the voting map with a magnitude of the gradient vector.

7 . The method of claim 6 , wherein fitting the ellipse comprises determining a center of the iris based upon the value of each pixel of the voting map.

8 . The method of claim 5 , wherein each of the plurality of ellipse hypotheses comprises one or more of a rotation angle, a radius, and a long-short axis ratio.

9 . An eye-tracking system comprising
an image sensor configured to acquire image data; a logic subsystem; and a storage subsystem comprising instructions stored thereon that are executable by the logic subsystem to:
detect a face of a user in the image data,
locate the eye in a region of the face in the image data to obtain an eye image,
normalize one or more of a scale and an illumination of the eye image,
determine a voting map for each of a plurality of ellipse hypotheses,
fit an ellipse to an iris of the eye in the eye image based upon the voting map of each ellipse hypothesis, and
output a determination of a gaze direction based upon the ellipse fitted.

10 . The eye-tracking system of claim 9 , wherein the instructions are executable to normalize the scale of the eye image by scaling the eye image to normalize a distance between features in the eye image.

11 . The eye-tracking system of claim 9 , wherein the instructions are executable to normalize the illumination of the eye image by forming a gray scale image from the eye image and normalizing intensity of the grayscale image.

12 . The eye-tracking system of claim 9 , wherein the instructions are further executable to perform segmentation on the image data to mask out one or more of a non-eye area and a non-iris area of the eye image prior to fitting the ellipse.

13 . The eye-tracking system of claim 9 , wherein the instructions are executable to fit the ellipse by, for each pixel of the eye image, determining a gradient vector for the pixel, and, for each voting map, updating a value of a corresponding pixel of the voting map with a magnitude of the gradient vector.

14 . The eye-tracking system of claim 13 , wherein the instructions are executable to fit the ellipse by determining a center of the iris based upon the value of each pixel of the voting map.

15 . An eye-tracking system comprising
an image sensor configured to acquire image data; a logic subsystem; and a storage subsystem comprising instructions stored thereon that are executable by the logic subsystem to:
detect a face of a user from the image data,
locate the eye in a region of the face from the image data to obtain an eye image,
normalize one or more of a scale and an illumination of the eye image,
perform segmentation on the image data to mask out one or more of non-eye areas and non-iris areas of the eye image,
fit an ellipse to an iris of the eye in the eye image based upon applying a plurality of ellipse hypotheses, and
output a determination of a gaze direction based upon the ellipse fitted.

16 . The eye-tracking system of claim 15 , wherein the instructions are executable to normalize the scale of the eye image by scaling the eye image to normalize a distance between features in the eye image.

17 . The eye-tracking system of claim 15 , wherein the instructions are executable to normalize the illumination of the eye image by forming a gray scale image from the eye image and normalizing intensity of the grayscale image.

18 . The eye-tracking system of claim 15 , wherein the instructions are executable to determine for each ellipse hypothesis a voting map corresponding to the eye image.

19 . The eye-tracking system of claim 15 , wherein the instructions are executable to fit the ellipse by, for each pixel of the eye image, determining a gradient vector for the pixel, and updating a value of a corresponding pixel of the voting map with a magnitude of the gradient vector.

20 . The eye-tracking system of claim 19 , wherein the instructions are executable to fit the ellipse by determining a center of the iris based upon the value of each pixel of the voting map.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Wu Dijia
• Conrad Michael J
• Chu Chun-Te
• Hulten Geoffrey John

Classifications

• G06K9/4661

  Physics · mapped topic

• G06T3/40

  Scaling of whole images or parts thereof, e.g. expanding or contracting · CPC title

• G06K2009/4666

  Physics · mapped topic

• G06K9/52

  Physics · mapped topic

• G06K9/0061 Primary

  Physics · mapped topic