Adaptive high dynamic range camera

• US 9,137,463 B2
• Filed: 05/12/2011
• Issued: 09/15/2015
• Est. Priority Date: 05/12/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Gilboa, Guy, Cohen, David, Yahav, Giora, Larry, Eli, Felzenshtein, Shlomo
• Primary Examiner(s): Patel, Jay
• Assistant Examiner(s): HUANG, FRANK F
• Application Number:
  US13/106,844
• Publication Number:
  US 20120287242A1
• Time in Patent Office: 1,587 Days
• Field of Search: 348/46, 348/E13.074
• US Class Current: 1/1
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: H04N 13/271 wherein the generated image signals comprise depth maps or disparity maps
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 25/46 by combining or binning pixels

Abstract

An embodiment of the invention provides a time of flight 3D camera comprising a photosensor having a plurality of pixels that generate and accumulate photoelectrons responsive to incident light, which photosensor is tiled into a plurality of super pixels, each partitioned into a plurality of pixel groups and a controller that provides a measure of an amount of light incident on a super pixel responsive to quantities of photoelectrons from pixel groups in the super pixel that do not saturate a readout pixel comprised in the photosensor.

Claims

1. A camera comprising:

a photosensor comprising a plurality of pixels configured to accumulate photoelectrons responsive to incident light, which photosensor is tiled to a plurality of super pixels, each partitioned into a plurality of pixel groups;

a readout pixel configured to receive photoelectrons from the pixel groups;

circuitry that operates to provide a measure of how many photoelectrons are contained in the readout pixel; and

a controller configured to;

transfer photoelectrons accumulated in each pixel group in a super pixel of the plurality of super pixels into the readout pixel to acquire a measure provided by the circuitry of the accumulation of photoelectrons in the pixel group;

determine responsive to the measures which pixel groups have an accumulation of photoelectrons that does not saturate the readout pixel and which pixel groups have an accumulation of photoelectrons that saturates the readout pixel; and

determine a measure of the number of photoelectrons in the super pixel responsive to a function of the measurements of accumulations of photoelectrons in pixel groups of the plurality of pixel groups that do not saturate the readout pixel, which function has a form determined responsive to measurements of the number of photoelectrons in at least two of the pixel groups and is independent of accumulations of photoelectrons in pixel groups that do saturate the readout pixel.

2. The camera according to claim 1 wherein the pixel groups in a super pixel are non-overlapping.

3. The camera according to claim 1 wherein no two pixel groups in a super pixel comprise a same number of pixels.

4. The camera according to claim 3 wherein the controller determines accumulations of photoelectrons for the pixel groups sequentially in increasing order of the number of pixels the pixel groups comprise.

5. The camera according to claim 1 wherein the pixels are arrayed in rows and columns.

6. The camera according to claim 5 wherein the super pixels are arrayed in rows and columns.

7. The camera according to claim 6 wherein the super pixels are QQVGA pixels each comprising sixteen pixels.

8. The camera according to claim 7 wherein the pixel groups comprise respectively one, three and twelve pixels.

9. The camera according to claim 8 wherein the pixels comprised in pixel groups comprising one and three pixels are located in a same column or row of pixels.

10. The camera according to claim 1 controllable to determine distances to features of a scene that the camera images.

11. The camera according to claim 10 wherein the camera is a time of flight 3D camera.

12. The camera according to claim 1 wherein to determine which pixel groups have an accumulation of photoelectrons that saturates the readout pixel, the controller:

determines a smallest pixel group comprised in the super pixel having an accumulation of photoelectrons that saturates the readout pixel; and

determines that accumulations of photoelectrons in pixel groups in the super pixel larger than the smallest pixel group having an accumulation of photoelectrons that saturates the readout pixel, saturates the readout pixel.

13. The camera according to claim 12 wherein the measure of the total number of photoelectrons in the super pixel is equal to a measure of the total accumulation of photoelectrons in pixel groups smaller than the smallest pixel group having an accumulation of photoelectrons that saturates the readout pixel, multiplied by a number equal to a number of pixels in the super pixel divided by a total number of pixels in the pixel groups smaller than the smallest pixel group having an accumulation of photoelectrons that saturates the readout pixel.

14. The camera according to claim 13 wherein the controller determines that a measure of the number of photoelectrons in the superpixel cannot be provided if the accumulation of photoelectrons in each of the pixel groups in the super pixel is indicated as saturating the readout pixel.

15. A method of measuring intensity of light incident on a photosensor comprising a plurality of light sensitive pixels that accumulate photoelectrons responsive to incident light, the method comprising:

tiling the photosensor into a plurality of super pixels, each partitioned into a plurality of pixel groups;

determining measures of amounts of photoelectrons accumulated by pixel groups to determine which pixel groups in a super pixel acquire an accumulation of photoelectrons responsive to the incident light that saturates a readout pixel and which pixel groups do not acquire an accumulation of photoelectrons that saturate the readout pixel; and

determining a measure of an accumulation of photoelectrons for the super pixel responsive to a function of the measurements of accumulations of photoelectrons determined not to saturate the readout pixel that has a form determined responsive to measurements of the number of photoelectrons in at least two of the pixel groups and is independent of the accumulations of photoelectrons determined to saturate the readout pixel.