DETERMINING EXPOSURE TIME IN A DIGITAL CAMERA

• US 20100182444A1
• Filed: 01/16/2009
• Published: 07/22/2010
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hegenbarth, Hannes, Ponticelli, Martin Josef, Kimchi, Gur, Curlander, John Charles, Kroepfl, Michael
• Granted Patent: US 8,675,122 B2
• Time in Patent Office: Days
• US Class Current: 348/222.100
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/90 Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums
• CPC Class Codes: H04N 25/46 by combining or binning pixels

Abstract

A digital camera described herein includes an analyzer component that analyzes a histogram of a first image, wherein the first image has a first resolution. The digital camera also includes a setter component that sets an exposure time for capturing a second image based at least in part upon the analysis of the histogram of the first image, wherein the second image has a second resolution, and wherein the first resolution of the first image is less than the second resolution of the second image.

Claims

1. A system comprising the following computer-executable components:

an analyzer component that analyzes a histogram of a first image, wherein the first image has a first resolution; and

a setter component that sets an exposure time for capturing a second image based at least in part upon the analysis of the histogram of the first image, wherein the second image has a second resolution, and wherein the first resolution of the first image is less than the second resolution of the second image.

2. The system of claim 1, further comprising a configuration component that configures a camera to capture the first image at the first resolution.

3. The system of claim 2, further comprising a binner component that bins intensity values from cells in an image sensor to cause the first image to be of the first resolution.

4. The system of claim 1, wherein the setter component is configured to set an exposure time for the first image.

5. The system of claim 4, wherein the setter component is configured to set the exposure time for the first image at approximately ten microseconds.

6. The system of claim 1, further comprising a histogram generator component that generates the histogram, wherein the histogram includes a plurality of different intensity values and a number of occurrences in the first image of the plurality of different intensity values.

7. The system of claim 6, wherein the analysis undertaken by the analyzer component comprises determining a white point value, wherein the white point value corresponds to an intensity value where a predefined percentage of bins have an intensity value no higher than the determined white point value.

8. The system of claim 7, wherein the setter component sets the exposure time for capturing the second image based at least in part upon the determined white point value.

9. The system of claim 8, wherein the setter component sets the exposure time for capturing the second image based at least in part upon an exposure time used to capture the first image.

12. The system of claim 1, further comprising:

a partitioner component that partitions the first image into a plurality of partitions; and

a weight assigner component that assigns weights to each of the plurality of partitions, wherein the setter component sets the exposure time for capturing the second image based at least in part upon the weights assigned to each of the plurality of partitions.

13. The system of claim 12, wherein the setter component determines an exposure time for each of the plurality of partitions.

10. The system of 9, wherein the setter component sets the exposure time for capturing the second image based at least in part upon a binning factor used to cause the first image to be of the first resolution.

11. The system of claim 10, wherein the setter component sets the exposure time for capturing the second image based at least in part upon a target gray value of the second image.

14. A method comprising the following computer-executable acts:

capturing a first image that has a first resolution;

processing the first image to determine an exposure time to use when capturing a second image of a second resolution based at least in part upon an analysis of the first image, wherein the first resolution is less than the second resolution; and

capturing the second image of the second resolution using the determined exposure time.

15. The method of claim 14, wherein the second image is captured within twenty milliseconds of the first image being captured.

16. The method of claim 14, further comprising using binning to cause the first image to be of the first resolution.

17. The method of claim 16, further comprising setting an exposure time of ten microseconds for capturing the first image.

18. The method of claim 16, further comprising:

generating a histogram that includes a number of occurrences of intensity of charges pertaining to a plurality of bins; and

determining the exposure time for the second image based at least in part upon the histogram.

19. The method of claim 14, further comprising:

partitioning the first image into at least a first partition and a second partition;

assigning a first weight to the first partition;

assigning a second weight to the second partition;

determining a first exposure time for the first partition;

determining a second exposure time for the second partition; and

setting the exposure time for the second image based at least in part upon the first exposure time, the second exposure time, the first weight, and the second weight.

20. A computer-readable medium in a digital camera comprising instructions that, when executed by a processor, perform the following acts:

receive a first trigger signal;

responsive to receipt of the first trigger signal, cause a first image to be captured in an image sensor;

bin pixels by a binning factor greater than one when reading out the first image from the image sensor to cause the first image to be of a first resolution;

compute an intensity histogram that indicates a number of occurrences of each of a plurality of intensity values corresponding to the first image of the first resolution;

determine an exposure time for capturing a second image based at least in part upon an analysis of the intensity histogram;

receive a second trigger signal; and

responsive to the second trigger signal, capture the second image at a second resolution, wherein the second resolution is higher than the first resolution.