4D Light Field Cameras

• US 20100265386A1
• Filed: 06/30/2010
• Published: 10/21/2010
• Est. Priority Date: 02/06/2007
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Raskar, Ramesh, Agrawal, Amit K.
• Granted Patent: US 7,965,936 B2
• Time in Patent Office: Days
• US Class Current: 348/340
• CPC Class Codes: G02B 27/0075 with means for altering, e.g. increasing, the depth of field or depth of focus

Abstract

A camera acquires a 4D light field of a scene. The camera includes a lens and sensor. A mask is arranged in a straight optical path between the lens and the sensor. The mask including an attenuation pattern to spatially modulate the 4D light field acquired of the scene by the sensor. The pattern has a low spatial frequency when the mask is arranged near the lens, and a high spatial frequency when the mask is arranged near the sensor.

Claims

1. An apparatus for sensing depth in a scene, comprising:

a lens;

a sensor; and

a mask arranged in an aperture plane of the lens, wherein the mask includes an attenuation pattern to spatially modulate a 4D light field acquired of the scene, and wherein the pattern has a low spatial frequency to precisely sense depth in the scene acquired by the sensor, and wherein the mask is arranged on an optical path from the lens to the sensor.

2. The apparatus of claim 1, in which the sensor acquires a sequence of images of the scene.

3. The apparatus of claim 1, in which the mask uses polarizing effects.

4. The apparatus of claim 1, in which the mask heterodynes the 4D light field.

5. The apparatus of claim 1, in which the sensor produces an input image, and further comprising:

means for reconstructing the 4D light field from the input image.

6. The apparatus of claim 1, wherein the mask preserves high spatial frequencies in an out-of-focus image.

7. The apparatus of claim 1, in which the sensor produces a defocused blur input image.

8. The apparatus of claim 1, in which the mask is placed at an angle with respect to the optical path.

9. The apparatus of claim 8, in which the in-focus output image has an increased depth of field.

10. The apparatus of claim 5, further comprising:

means for synthesizing a novel refocused image from the reconstructed 4D light field.

11. The apparatus of claim 5, further comprising:

means for generating a high resolution image from the reconstructed 4D light field.

12. The apparatus of claim 1, in which the pattern includes colors.

13. The apparatus of claim 5, further comprising:

means for refocusing the input image from the reconstructed 4D light field at a different depth of field.

14. The apparatus of claim 5, further comprising:

means for deblurring the input image to remove out of focus blur.

15. A method for acquiring a 4D light field of a scene, comprising the steps of:

passing a 4D light field through a lens to a sensor along a straight optical path; and

modulating the 4D light field with a mask, wherein the mask is arranged in an aperture plane of the lens, wherein the mask includes an attenuation pattern to spatially modulate a 4D light field acquired of the scene, and wherein the pattern has a low spatial frequency to precisely sense depth in the scene acquired by the sensor, and wherein the mask is arranged on an optical path from the lens to the sensor.