Systems and methods for autofocus trigger

• US 10,061,182 B2
• Filed: 06/09/2017
• Issued: 08/28/2018
• Est. Priority Date: 07/02/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Dayana, Venkata Ravi Kiran, Shanmugavadivelu, Karthikeyan, Liu, Shizhong, Lou, Ying Chen, Wu, Hung-Hsin, Ravirala, Narayana Karthik Sadanandam, Golikeri, Adarsh Abhay
• Primary Examiner(s): Laballe, Clayton E
• Assistant Examiner(s): Smith, Linda B
• Application Number:
  US15/618,409
• Publication Number:
  US 20170277018A1
• Time in Patent Office: 445 Days
• Field of Search: 396125, 396322, 396325, 396333
• CPC Class Codes: G03B 13/36 Autofocus systems
• CPC Class Codes: H04N 23/959 by adjusting depth of field during image capture, e.g. maximising or setting range based on scene characteristics

Abstract

Method and systems for autofocus triggering focusing are disclosed herein. In one example, a system may include a lens, a memory component configured to store lens parameters of the lens and regions of focus corresponding to the lens parameters, and a processor coupled to the memory and the lens. The processor may be configured to focus the lens on a target object at a first instance of time, receive information indicative of distances from an imaging device to the target object over a period of time, obtain lens parameters of the lens, and determine a region of focus, and trigger the lens to re-focus on the target object if the distance to the target object indicates the target object is outside of the region of focus and the distance to the target object is unchanged for a designated time period.

Claims

1. An imaging device, comprising:

a main camera comprising a first image sensor and a first lens, the first image sensor configured to generate a first image of a target object at a first focal length of the first lens;

an auxiliary camera comprising a second image sensor configured to generate a second image of the target object;

a memory component configured to store lens parameters for the main camera and depths of field corresponding to the lens parameters; and

a processor configured to communicate with the memory component, the processor configured to;

determine a distance from the imaging device to the target object based on a disparity between a first position of the target object in the first image and a second position of the target object in the second image;

retrieve, from the memory component, a lens parameter of the lens parameters for the main camera, the lens parameter corresponding to capture of the first image;

determine, based on the retrieved lens parameter, a depth of field at which a sharp image of the target object can be formed on the main camera;

trigger the first lens to focus on the target object based on the depth of field;

determine whether the distance from the imaging device to the target object is unchanged over a time period; and

in response to determining the distance from the imaging device to the target object is unchanged over the time period, capture an image of the target object with the main camera with the first lens focused according to the depth of field.

2. The imaging device of claim 1, wherein the processor is configured to determine, based on the retrieved lens parameter, a near distance and a far distance bounding the depth of field and including the distance from the imaging device to the target object, wherein the target object appears sharp in the image, and wherein objects located beyond the far distance appear un-sharp in the image.

3. The imaging device of claim 1, wherein the auxiliary camera comprises a second lens.

4. The imaging device of claim 3, wherein the memory component is configured to store a stereo baseline value representing a separation distance between the first lens and the second lens, and wherein the processor is configured to:

access the stereo baseline value from the memory;

determine the distance from the imaging device to the target object based on the stereo baseline value, the first focal length of the first lens, and the disparity.

5. The imaging device of claim 4, the second lens having a second focal length, wherein, to determine the distance from the imaging device to the target object, the processor is configured:

multiply the stereo baseline value by a focal length generated based on the first and second focal lengths; and

divide a result of the multiplying by the disparity.

6. The imaging device of claim 1, wherein the processor is configured to:

identify a central point on the object;

determine the first position of the target object in the first image and the second position of the target object in the second image based, respectively, on first and second positionings of the central point; and

calculate the disparity based on a horizontal distance between the first and second positionings of the central point.

7. The imaging device of claim 1, wherein the processor is configured to determine the disparity based on a position of the first lens during capture of the first image.

8. The imaging device of claim 1, wherein the processor is configured to receive additional information indicative of distances from the imaging device to the target object over the time period.

9. A method of focusing an imaging device having a main camera including a first image sensor and a first lens, and an auxiliary camera including a second image sensor, the method comprising:

capturing with the first image sensor a first image of a target object at a first focal length of the first lens;

capturing with the second image sensor a second image of the target object;

determining a distance from the imaging device to the target object based on a disparity between a first position of the target object in the first image and a second position of the target object in the second image;

retrieving, from a memory component, a lens parameter for the main camera, the lens parameter corresponding to capture of the first image;

determining, based on the retrieved lens parameter, a depth of field at which a sharp image of the target object can be formed on the main camera;

triggering the first lens to focus on the target object based on the depth of field; and

determining whether the distance from the imaging device to the target object is unchanged over a time period; and

in response to determining that the distance from the imaging device to the target object is unchanged over the time period, capturing an image of the target object with the main camera with the first lens focused according to the depth of field.

10. The method of claim 9, further comprising determining, based on the retrieved lens parameter, a near distance and a far distance bounding the depth of field and including the distance from the imaging device to the target object, wherein the target object appears sharp in the image, and wherein objects located beyond the far distance appear un-sharp in the image.

11. The method of claim 9, wherein the auxiliary camera comprises a second lens, the method further comprising:

retrieving a stereo baseline value representing a separation distance between the first lens and the second lens from the memory component; and

determining the distance from the imaging device to the target object based on the stereo baseline value, the first focal length of the first lens, and the disparity.

12. The method of claim 11, wherein the second lens has a second focal length, the method further comprising determining the distance from the imaging device to the target object by:

multiplying the stereo baseline value by a focal length generated based on the first and second focal lengths; and

dividing a result of the multiplying by the disparity.

13. The method of claim 9, further comprising:

identifying a central point on the object;

determining the first position of the target object in the first image and the second position of the target object in the second image based, respectively, on first and second positionings of the central point; and

calculating the disparity based on a horizontal distance between the first and second positionings of the central point.

14. The method of claim 9, further comprising determining the disparity based on a position of the first lens during capture of the first image.

15. The method of claim 9, further comprising receiving additional information indicative of distances from the imaging device to the target object over the time period.

16. A non-transitory computer-readable medium storing instructions that, when executed by one or more computing devices, configure the one or more computing devices to perform a method comprising:

capturing with the first image sensor a first image of a target object at a first focal length of the first lens;

capturing with the second image sensor a second image of the target object;

determining a distance from the imaging device to the target object based on a disparity between a first position of the target object in the first image and a second position of the target object in the second image;

retrieving, from a memory component, a lens parameter for the main camera, the lens parameter corresponding to capture of the first image;

determining, based on the retrieved lens parameter, a depth of field at which a sharp image of the target object can be formed on the main camera;

triggering the first lens to focus on the target object based on the depth of field; and

determining whether the distance from the imaging device to the target object is unchanged over a time period; and

in response to determining that the distance from the imaging device to the target object is unchanged over the time period, capturing an image of the target object with the main camera with the first lens focused according to the depth of field.

17. The non-transitory computer-readable medium of claim 16, wherein the method further comprises determining, based on the retrieved lens parameter, a near distance and a far distance bounding the depth of field and including the distance from the imaging device to the target object, wherein the target object appears sharp in the image, and wherein objects located beyond the far distance appear un-sharp in the image.

18. The non-transitory computer-readable medium of claim 16, wherein the auxiliary camera comprises a second lens, wherein the method further comprises:

retrieving a stereo baseline value representing a separation distance between the first lens and the second lens from the memory component; and

determining the distance from the imaging device to the target object based on the stereo baseline value, the first focal length of the first lens, and the disparity.

19. The non-transitory computer-readable medium of claim 18, wherein the second lens has a second focal length, wherein the method further comprises determining the distance from the imaging device to the target object by:

multiplying the stereo baseline value by a focal length generated based on the first and second focal lengths; and

dividing a result of the multiplying by the disparity.

20. The non-transitory computer-readable medium of claim 16, wherein the method further comprises:

identifying a central point on the object;

determining the first position of the target object in the first image and the second position of the target object in the second image based, respectively, on first and second positionings of the central point; and

calculating the disparity based on a horizontal distance between the first and second positionings of the central point.

21. The non-transitory computer-readable medium of claim 16, wherein the method further comprises determining the disparity based on a position of the first lens during capture of the first image.

22. The non-transitory computer-readable medium of claim 16, wherein the method further comprises receiving additional information indicative of distances from the imaging device to the target object over the time period.