Focused plenoptic camera employing microlenses with different focal lengths

• US 8,400,555 B1
• Filed: 12/01/2009
• Issued: 03/19/2013
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: Adobe Inc.
• Original Assignee: Adobe Systems Incorporated (Adobe Inc.)
• Inventors: Georgiev, Todor G., Lumsdaine, Andrew
• Primary Examiner(s): SELBY, GEVELL V
• Application Number:
  US12/628,437
• Time in Patent Office: 1,204 Days
• Field of Search: 348/222.1, 348/335, 348/340, 348/345
• US Class Current: 348/345
• CPC Class Codes: H04N 23/676 Bracketing for image capture at varying focusing conditions
• CPC Class Codes: H04N 23/957 Light-field or plenoptic cameras or camera modules

Abstract

Methods and apparatus for capturing and rendering images with focused plenoptic cameras employing microlenses with different focal lengths. A focused plenoptic camera that includes an array of microlenses with at least two different focal lengths may be used to simultaneously capture microimages from at least two different planes at different distances from the microlens array. Image operations such as refocusing and focus bracketing may be performed on flats captured with the camera. Images may be constructed from subsets of the microimages captured using each type of microlens, thus creating multiple images each focused at a different depth. An array of stacked microlenses including stacks that provide different focal lengths may be used. The lens stacks may be provided by stacking two microlenses arrays on top of each other in the camera.

Claims

1. A camera, comprising:

a photosensor configured to capture light projected onto the photosensor;

an objective lens, wherein the objective lens is configured to refract light from a scene located in front of the camera to form an image of the scene at a plurality of different focal planes of the objective lens;

an optical element array positioned between the objective lens and the photosensor, wherein the optical element array comprises a plurality of optical elements, wherein the plurality of optical element are focused on the focal planes and not on the objective lens, and wherein at least two of the optical elements are of different focal lengths and are thus focused at different ones of the plurality of focal planes; and

wherein each optical element of the optical element array is configured to project a separate portion of the image of the scene formed at the focal plane on which the optical element is focused onto a separate location on the photosensor.

2. The camera as recited in claim 1, wherein each optical element in the optical element array comprises a microlens, wherein at least two of the microlenses in different ones of the optical elements are of different focal lengths to thus focus at different ones of the plurality of focal planes.

3. The camera as recited in claim 1, wherein the optical element array is a microlens array comprising a plurality of microlenses, wherein at least two of the microlenses are of different focal lengths to thus focus at different ones of the plurality of focal planes.

4. The camera as recited in claim 1, wherein each optical element in the optical element array comprises a stack of multiple microlenses aligned on the optical axes of the microlenses, wherein at least two of the microlens stacks in different ones of the optical elements provide different focal lengths to thus focus at different ones of the plurality of focal planes.

5. The camera as recited in claim 1, wherein the optical element array comprises two microlens arrays each comprising a plurality of microlenses, wherein the microlenses in the two microlens arrays are aligned on the optical axes of the microlenses, and wherein at least two of the microlenses in at least one of the two microlens arrays are of different focal lengths to thus focus at different ones of the plurality of focal planes.

6. The camera as recited in claim 5, wherein a first microlens array of the two microlens arrays is positioned proximate to the photosensor, and wherein a second microlens array is positioned proximate to the first microlens array between the first microlens array and the objective lens.

7. The camera as recited in claim 5, wherein the microlenses in the first microlens array are all of the same focal length, and wherein at least two of the microlenses in the second microlens array are of different focal lengths to thus focus at the different ones of the plurality of focal planes.

8. The camera as recited in claim 7, wherein the microlenses in the first microlens array are positioned at a distance b from the photosensor, where b is equal to the focal length of the microlenses in the first microlens array.

9. The camera as recited in claim 1, wherein the photosensor is configured to capture a flat comprising the separate portions of the image of the scene projected onto the photosensor by the optical elements, wherein each of the separate portions is in a separate region of the flat, and wherein at least two of the separate portions are captured from different ones of the plurality of focal planes according to the different focal lengths of the optical elements that project the at least two separate portions onto the photosensor.

10. The camera as recited in claim 9, wherein the camera is configured to store the captured flat to a memory device.

11. The camera as recited in claim 1, wherein the camera is configured so that the plurality of focal planes are positioned between the objective lens and the optical element array.

12. The camera as recited in claim 1, wherein the camera is configured so that the plurality of focal planes are positioned behind the photosensor.

13. A method, comprising:

receiving light from a scene at an objective lens of a camera;

refracting light from the objective lens to form an image of the scene at a plurality of different focal planes of the objective lens;

receiving light from the plurality of different focal planes at an optical element array positioned between the objective lens and a photosensor of the camera, wherein the optical element array comprises a plurality of optical elements, wherein the plurality of optical element are focused on the focal planes and not on the objective lens, and wherein at least two of the optical elements are of different focal lengths and are thus focused at different ones of the plurality of focal planes;

receiving light from the optical element array at the photosensor, wherein the photosensor receives a separate portion of the image of the scene formed at one of the plurality of focal planes from each optical element of the optical element array at a separate location on the photosensor, and wherein at least one subset of the separate portions differs from at least one other subset of the separate portions according to the different focal lengths of the optical elements in the optical element array corresponding to the microlenses that project the at least one subset of the separate portions onto the photosensor.

14. The method as recited in claim 13, wherein the optical element array is a microlens array comprising a plurality of microlenses, wherein at least two of the microlenses are of different focal lengths to thus focus at different ones of the plurality of focal planes.

15. The method as recited in claim 13, wherein the optical element array comprises two microlens arrays each comprising a plurality of microlenses, wherein the microlenses in the two microlens arrays are aligned on the optical axes of the microlenses, and wherein at least two of the microlenses in at least one of the two microlens arrays are of different focal lengths to thus focus at different ones of the plurality of focal planes.

16. The method as recited in claim 15, wherein a first microlens array of the two microlens arrays is positioned proximate to the photosensor, wherein a second microlens array is positioned proximate to the first microlens array between the first microlens array and the objective lens, wherein the microlenses in the first microlens array are all of the same focal length, wherein at least two of the microlenses in the second microlens array are of different focal lengths to thus focus at the different ones of the plurality of focal planes, and wherein the microlenses in the first microlens array are positioned at a distance b from the photosensor, where b is equal to the focal length of the microlenses in the first microlens array.

17. The method as recited in claim 13, further comprising capturing a flat comprising the separate portions of the image of the scene projected onto the photosensor by the microlenses, wherein each of the separate portions is in a separate region of the flat.

18. The method as recited in claim 17, further comprising:

appropriately combining the different separate portions from the subsets of the separate portions to generate a combined flat, wherein the combined flat comprises the combined separate portions of the image of the scene; and

appropriately assembling the plurality of combined separate portions to produce one or more images of the scene.

19. The method as recited in claim 17, further comprising:

appropriately assembling the separate portions from each of the subsets of the separate portions to generate two or more separate images of the scene each corresponding to a particular subset of the separate portions; and

appropriately combining at least two of the two or more separate images of the scene to produce a combined image of the scene.