Systems and methods for high dynamic range imaging using array cameras

• US 9,774,789 B2
• Filed: 03/07/2014
• Issued: 09/26/2017
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: FotoNation Limited (Adeia Inc.)
• Original Assignee: Fotonation Cayman Limited (Adeia Inc.)
• Inventors: Ciurea, Florian, Venkataraman, Kartik
• Primary Examiner(s): Tran, Nhan T
• Assistant Examiner(s): Yoder, III, Chriss
• Application Number:
  US14/773,742
• Publication Number:
  US 20160057332A1
• Time in Patent Office: 1,299 Days
• CPC Class Codes: H04N 23/13 with multiple sensors
• CPC Class Codes: H04N 23/45 for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/743 Bracketing, i.e. taking a series of images with varying exposure conditions
• CPC Class Codes: H04N 23/951 by using two or more images to influence resolution, frame rate or aspect ratio
• CPC Class Codes: H04N 25/581 acquired simultaneously
• CPC Class Codes: H04N 25/585 with pixels having different sensitivities within the sensor, e.g. fast or slow pixels or pixels having different sizes
• CPC Class Codes: H04N 25/70 SSIS architectures; Circuits associated therewith
• CPC Class Codes: H04N 5/265 Mixing
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

Systems and methods for high dynamic range imaging using array cameras in accordance with embodiments of the invention are disclosed. In one embodiment of the invention, a method of generating a high dynamic range image using an array camera includes defining at least two subsets of active cameras, determining image capture settings for each subset of active cameras, where the image capture settings include at least two exposure settings, configuring the active cameras using the determined image capture settings for each subset, capturing image data using the active cameras, synthesizing an image for each of the at least two subset of active cameras using the captured image data, and generating a high dynamic range image using the synthesized images.

Claims

1. A method of performing high dynamic range image capture adaptive to scene object distance using an array camera, the method comprising:

capturing initial image data using at least one active camera from a plurality of cameras in the array camera;

determining whether to utilize high dynamic range imaging for performing image capture using a processor configured by software; and

when high dynamic range imaging is determined to be utilized;

generating a depth map based on the initial image data using a processor configured by software;

determining whether an object is within a predetermined distance from the array camera by evaluating the depth map using the processor configured by software;

defining a first subset and a second subset of active cameras within the plurality of cameras in the array camera using the processor configured by software;

when the object is not within the predetermined distance;

determining a first exposure setting for the first subset of active cameras and a second exposure setting for the second subset of active cameras using the processor configured by software;

configuring the first subset with the first exposure setting and the second subset with the second exposure setting using the processor configured by software;

capturing single-frame image data using the first subset and the second subset of active cameras, wherein the single-frame image data includes at least one first single-frame image captured at the first exposure setting and at least one second single-frame image captured at the second exposure setting; and

synthesizing a first exposure image based on the at least one first single-frame image and a second exposure image based on the at least one second single-frame image using the processor configured by software;

and

generating a high dynamic range image from the first exposure image and the second exposure image using the processor configured by software.

2. The method of claim 1, further comprising:

when the object is within the predetermined distance;

determining a first exposure setting and a second exposure setting for the first subset of active cameras using the processor configured by software;

configuring the first subset of active cameras with the first exposure setting and successively with the second exposure setting using the processor configured by software;

capturing multiple-frame image data using the first subset of active cameras, wherein the multiple-frame image data includes at least one first multiple-frame image captured at the first exposure setting and at least one second multiple-frame image captured successively at the second exposure setting; and

synthesizing a first exposure image based on the at least one first multiple-frame image and a second exposure image based on the at least one second single-frame image using the processor configured by software.

3. The method of claim 1, further comprising:

estimating a dynamic range of a scene based on the initial image data using a processor configured by software; and

determining whether the dynamic range exceeds a predetermined threshold using a processor configured by software;

wherein determining whether to utilize high dynamic range imaging includes determining to utilize high dynamic range imaging when the dynamic range exceeds the predetermined threshold.

4. The method of claim 1, further comprising:

synthesizing a preview image using the initial image data using a processor configured by software; and

generating a preview of the preview image using a processor configured by software;

wherein generating a depth map is further based on the preview.

5. The method of claim 1, wherein the predetermined distance is based on a disparity between furthest cameras within the plurality of cameras in the array camera.

6. The method of claim 1, wherein determining the first exposure setting and the second exposure setting is performed using exposure bracketing.

7. The method of claim 1, wherein the plurality of cameras is formed by a camera module comprising an array of individual cameras.

8. The method of claim 7, wherein the camera module comprises:

an imager array including an array of focal planes, where each focal plane comprises an array of light sensitive pixels; and

an optic array including an array of lens stacks, where each lens stack creates an optical channel that forms an image on the array of light sensitive pixels within a corresponding focal plane;

wherein pairings of lens stacks and focal planes form multiple cameras including the plurality of cameras.

9. The method of claim 8, wherein the lens stacks within each optical channel sample the same object space with sub-pixel offsets to provide sampling diversity.

10. The method of claim 1, wherein synthesizing a first exposure image and a second exposure image further comprises performing super-resolution processing with respect to the single-frame image data, to synthesize an image for each of the first subset and the second subset of active cameras with increased resolution.

11. An array camera, comprising:

a plurality of cameras;

a processor in communication with the plurality of cameras;

a memory connected to the processor and configured to store a program, wherein the program configures the processor to;

capture initial image data using at least one active camera from the plurality of cameras;

determine whether to utilize high dynamic range imaging for performing image capture using a processor configured by software; and

when high dynamic range imaging is determined to be utilized;

generate a depth map based on the initial image data using a processor configured by software;

determine whether an object is within a predetermined distance from the array camera by evaluating the depth map using the processor configured by software;

define a first subset and a second subset of active cameras within the plurality of cameras using the processor configured by software;

when the object is not within the predetermined distance;

determine a first exposure setting for the first subset of active cameras and a second exposure setting for the second subset of active cameras using the processor configured by software;

configure the first subset with the first exposure setting and the second subset with the second exposure setting using the processor configured by software;

capture single-frame image data using the first subset and the second subset of active cameras, wherein the single-frame image data includes at least one first single-frame image captured at the first exposure setting and at least one second single-frame image captured at the second exposure setting; and

synthesize a first exposure image based on the at least one first single-frame image and a second exposure image based on the at least one second single-frame image using the processor configured by software;

and

generate a high dynamic range image from the first exposure image and the second exposure image using the processor configured by software.

12. The array camera of claim 11, wherein the program further configures the processor to:

when the object is within the predetermined distance;

determine a first exposure setting and a second exposure setting for the first subset of active cameras using the processor configured by software;

configure the first subset of active cameras with the first exposure setting and successively with the second exposure setting using the processor configured by software;

capture multiple-frame image data using the first subset of active cameras, wherein the multiple-frame image data includes at least one first multiple-frame image captured at the first exposure setting and at least one second multiple-frame image captured successively at the second exposure setting; and

synthesize a first exposure image based on the at least one first multiple-frame image and a second exposure image based on the at least one second single-frame image using the processor configured by software.

13. The array camera of claim 11, wherein the program further configures the processor to:

estimate a dynamic range of a scene based on the initial image data using a processor configured by software; and

determine whether the dynamic range exceeds a predetermined threshold using a processor configured by software;

wherein determining whether to utilize high dynamic range imaging includes determining to utilize high dynamic range imaging when the dynamic range exceeds the predetermined threshold.

14. The array camera of claim 11, wherein the program further configures the processor to:

synthesize a preview image using the initial image data using a processor configured by software; and

generate a preview of the preview image using a processor configured by software;

wherein generating a depth map is further based on the preview.

15. The array camera of claim 11, wherein the predetermined distance is based on a disparity between furthest cameras within the plurality of cameras in the array camera, such that occlusion artifacts in images captured by the array camera are minimized.

16. The array camera of claim 11, wherein determining the first exposure setting and the second exposure setting is performed using exposure bracketing.

17. The array camera of claim 11, wherein the plurality of cameras is formed by a camera module comprising an array of individual cameras.

18. The array camera of claim 17, wherein the camera module comprises:

an imager array including an array of focal planes, where each focal plane comprises an array of light sensitive pixels; and

an optic array including an array of lens stacks, where each lens stack creates an optical channel that forms an image on the array of light sensitive pixels within a corresponding focal plane;

wherein pairings of lens stacks and focal planes form multiple cameras including the plurality of cameras.

19. The array camera of claim 18, wherein the lens stacks within each optical channel sample the same object space with sub-pixel offsets to provide sampling diversity.

20. The array camera of claim 11, wherein synthesizing a first exposure image and a second exposure image further comprises performing super-resolution processing with respect to the single-frame image data, to synthesize an image for each of the first subset and the second subset of active cameras with increased resolution.