PREDICTIVE AUTOFOCUSING SYSTEM

• US 20100034529A1
• Filed: 08/07/2008
• Published: 02/11/2010
• Est. Priority Date: 08/07/2008
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Honeywell International Inc.
• Inventors: Jelinek, Jan
• Granted Patent: US 8,213,782 B2
• Time in Patent Office: Days
• US Class Current: 396/95
• CPC Class Codes: G02B 7/36 using image sharpness techniques , e.g. image processing techniques for generating autofocus signals image data processing per se G06T; in cameras having a solid state image sensor H04N23/67
• CPC Class Codes: G03B 13/36 Autofocus systems
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

A system for providing a predictive autofocus prior to capturing an image of an iris of a subject. A sequence of images of the subject may be taken with a visible light sensitive camera. A speed and/or location of the subject may be estimated from the images. An encounter may be when the subject is within focus of the camera or, in other words, a focus distance and subject distance coincide. The focus may be determined in accordance with an intensity variance determination of the subject in the image, and more particularly of a subject'"'"'s eye within a window of an image. Upon an encounter, an image of the iris of the eye may be captured with an infrared sensitive camera.

Claims

1. A method for autofocusing comprising:

taking a sequence of images of a subject with a camera;

estimating a first time of an encounter of the subject from the images;

computing one or more encounters subsequent to the first time of an encounter; and

taking an image of the subject at one or more times of an encounter; and

wherein an encounter indicates that at least a portion of the subject is within a focus of the camera.

2. The method of claim 1, wherein:

the at least a portion of the subject is covered by a window in the images; and

the window includes an eye of the subject.

3. The method of claim 2, wherein computing an encounter is based on intensity variance of an area in the window centered on the eye.

4. The method of claim 3, wherein an encounter is achieved when either just the focus or the subject moves, or both the focus and the subject move.

5. The method of claim 4, wherein upon at least one encounter, the camera takes an image of an iris of the eye.

6. The method of claim 5, wherein the image of the iris is taken under infrared light.

7. The method of claim 6, wherein the camera comprises one or more sensors for taking the sequence of images of a subject and for taking the image of an iris.

8. A predictive autofocusing system comprising:

a camera for taking images of a subject; and

a processor connected to the camera; and

wherein the processor is for processing the images from the camera to indicate an encounter wherein the subject is within a focus of the camera.

9. The system of claim 8, wherein the processor is for processing images to estimate a time of a future encounter.

10. The system of claim 8, wherein the processing of images is for determining intensity variance of an area of an eye of the subject to determine whether an amount of focus of the eye in the images is sufficient for an encounter.

11. The system of claim 8, wherein upon an encounter, an image of an iris of an eye of the subject can be captured by the camera.

12. The system of claim 11, wherein an encounter is achieved by movement of either the subject or the focus of the camera, or of both the subject and a focus of the camera.

13. The system of claim 11, wherein the camera is for taking images of the subject in visible light for focusing, and for capturing an image of the iris in infrared light.

14. A method for focusing comprising:

taking images with a camera of a subject;

estimating a position and/or speed of the subject relative to the camera from the images;

computing a time of an encounter from the position and/or speed of the subject relative to the camera, wherein the encounter is at a time when the subject is within focus of the camera; and

taking an image of the subject upon the time of an encounter.

15. The method of claim 14, wherein the position and/or speed of the subject is estimated from image data of a window encompassing an eye of the subject in the images.

16. The method of claim 15, wherein the image data comprises an intensity variance proximate to the eye.

17. The method of claim 16, wherein an encounter is indicated when the intensity variance is at a certain level.

18. The method of claim 17, wherein an image of the eye is acquired during an encounter.

19. The method of claim 18, wherein the images having the image data are taken in visible light and the image of the eye is taken in infrared light.

20. The method of claim 17, further comprising deciding whether to move the focus to obtain an encounter, or have the subject move within a depth of the focus, or both.