Dynamic Autofocus Opertions

• US 20130076967A1
• Filed: 09/28/2011
• Published: 03/28/2013
• Est. Priority Date: 09/28/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: CHEN, Ting, BRUNNER, Ralph
• Granted Patent: US 8,908,083 B2
• Time in Patent Office: Days
• US Class Current: 348/345
• CPC Class Codes: H04N 1/2112 using still video cameras
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 2201/0084 Digital still camera
• CPC Class Codes: H04N 2201/0096 Portable devices
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 23/676 Bracketing for image capture at varying focusing conditions

Abstract

Systems, methods, and computer readable media for dynamically adjusting an image capture device'"'"'s autofocus (AF) operation based, at least in part, on the device'"'"'s orientation are described. In general, information about an image capture device'"'"'s orientation may be used to either increase the speed or improve the resolution of autofocus operations. More particularly, orientation information such as that available from an accelerometer may be used to reduce the number of lens positions (points-of-interest) used during an autofocus operation, thereby improving the operation'"'"'s speed. Alternatively, orientation information may be used to reduce the lens'"'"' range of motion while maintaining the number of points-of-interest, thereby improving the operation'"'"'s resolution.

Claims

1. An autofocus method for a digital image capture device having a full number of autofocus points-of-interest and a full autofocus range of motion, the method comprising:

receiving a signal from a sensor of the digital image capture device;

determining an orientation of the digital image capture device based at least in part on the signal;

determining a current autofocus range of motion based at least in part on the orientation, the current autofocus range of motion being less than the full autofocus range of motion; and

performing an autofocus operation using the current autofocus range of motion and an autofocus mode.

2. The method of claim 1, wherein the act of performing an autofocus operation comprises:

performing an autofocus operation using less than the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a first autofocus mode; and

performing an autofocus operation using the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a second autofocus mode.

3. The method of claim 2, wherein the first autofocus mode is selected if the orientation is determined to be more than a specified angle away from horizontal.

4. A non-transitory computer readable medium, comprising:

computer code to receive a signal from a sensor of a digital image capture device, the digital image capture device having a full number of autofocus points-of-interest and a full autofocus range of motion;

computer code to determine an orientation of the digital image capture device based at least in part on the signal;

computer code to determine a current autofocus range of motion based at least in part on the orientation, the current autofocus range of motion being less than the full autofocus range of motion; and

computer code to perform an autofocus operation using the current autofocus range of motion and an autofocus mode.

5. The non-transitory computer readable medium of claim 4, wherein the computer code to perform an autofocus operation comprises:

computer code to perform an autofocus operation using less than the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a first autofocus mode; and

computer code to perform an autofocus operation using the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a second autofocus mode.

6. An autofocus method for a digital image capture device having a full number of autofocus points-of-interest and a full autofocus range of motion, the method comprising:

receiving a signal from a sensor of the digital image capture device;

determining an orientation of the digital image capture device based at least in part on the signal;

determining a current autofocus range of motion based at least in part on the orientation, the current autofocus range of motion being less than the full autofocus range of motion;

performing an autofocus operation using less than the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a first autofocus mode; and

performing an autofocus operation using the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a second autofocus mode.

7. The method of claim 6, wherein the act of receiving a signal comprises receiving a signal from an accelerometer sensor.

8. The method of claim 6, wherein the full autofocus range of motion represents the maximum range of motion a lens assembly of the digital image capture device can move during an autofocus operation.

9. The method of claim 6, wherein the act of determining an orientation of the digital image capture device comprises determining the digital image capture device is in a horizontal-facing orientation.

10. The method of claim 9, wherein the act of determining the digital image capture device is in a horizontal-facing orientation comprises determining the digital image capture device is tilted at an angle within a specified range of being horizontal.

11. The method of claim 9, wherein the second mode is selected when the digital image capture device is determined to be in the horizontal-facing orientation.

12. The method of claim 11, wherein the first mode is selected when the digital image capture device is determined to be in an orientation other than the horizontal-facing orientation.

13. The method of claim 6, wherein the act of performing an autofocus operation using the first mode is faster than the act of performing an autofocus using the full number of autofocus points-of-interest and the full autofocus range of motion.

14. The method of claim 6, wherein the act of performing an autofocus operation comprises:

determining an autofocus parameter value for each of one or more locations in a first image of a scene;

determining an autofocus parameter value for each location in a second image of the scene corresponding to the one or more locations in the first image;

comparing the autofocus parameter values from the first image with the corresponding autofocus parameter values of the second image; and

adjusting a position of a lens of the digital image capture device based on the act of comparing.

19. An electronic device, comprising:

a lens assembly;

an actuator coupled to the lens assembly;

a digital image sensor configured to receive light from the lens assembly;

a memory operatively coupled to the digital image sensor;

an orientation sensor;

a programmable control unit operatively coupled to the actuator, memory and orientation sensor, wherein the memory includes computer code that, when executed by the programmable control unit, performs the method of claim 6.

20. The electronic device of claim 19, wherein the lens assembly comprises two or more individual lens elements.

21. The electronic device of claim 19, wherein the orientation sensor comprises an accelerometer.

15. A non-transitory computer readable medium, comprising:

computer code to receive a signal from a sensor of a digital image capture device, the digital image capture device having a full number of autofocus points-of-interest and a full autofocus range of motion;

computer code to determine an orientation of the digital image capture device based at least in part on the signal;

computer code to determine a current autofocus range of motion based at least in part on the orientation, the current autofocus range of motion being less than the full autofocus range of motion;

computer code to perform an autofocus operation using less than the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a first autofocus mode; and

computer code to perform an autofocus operation using the full number of autofocus points-of-interest and the current autofocus range of motion when the digital image capture device is in a second autofocus mode.

16. The non-transitory program storage device of claim 15, wherein the computer code to determine an orientation of the digital image capture device comprises computer code to determine the digital image capture device is in a horizontal-facing orientation.

17. The non-transitory program storage device of claim 16, wherein the computer code to determine the digital image capture device is in a horizontal-facing orientation comprises computer code to determine the digital image capture device is tilted at an angle within a specified range of being horizontal.

18. The non-transitory program storage device of claim 15, wherein the computer code to perform an autofocus operation comprises:

computer code to determine an autofocus parameter value for each of one or more locations in a first image of a scene;

computer code to determine an autofocus parameter value for each location in a second image of the scene corresponding to the one or more locations in the first image;

computer code to compare the autofocus parameter values from the first image with the corresponding autofocus parameter values of the second image; and

computer code to adjust a position of a lens of the digital image capture device based on the act of comparing.