Detecting ambient light levels in a vision system

• US 7,973,779 B2
• Filed: 10/26/2007
• Issued: 07/05/2011
• Est. Priority Date: 10/26/2007
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Masalkar, Prafulla
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Okebato; Sahlu
• Application Number:
  US11/924,633
• Publication Number:
  US 20090109193A1
• Time in Patent Office: 1,348 Days
• Field of Search: 345/173, 345/175, 356213-236, 116/202, 340/967, 340/948, 340/950, 340/951, 340/583, 340/815.4, 340/63, 340/469
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

The detection of ambient light on an optical touch-sensitive device is disclosed. For example, one disclosed embodiment comprises capturing an image of at least a portion of a display screen with a camera located within the display device, and determined if ambient light in the image is at an acceptable level for display screen operation. Then, a visual representation is displayed representing whether the ambient light level is acceptable for display screen operation.

Claims

1. A method of detecting ambient light in an optical touch-sensitive display device, the optical touch-sensitive display device comprising a display screen, an illuminant and an image sensor, the method comprising:

capturing an image of at least a portion of the display screen with the image sensor;

determining whether an ambient light level in the image is at an acceptable level for display screen operation; and

displaying a visual representation of whether the ambient light level is acceptable for display screen operation, the visual representation further indicating, if the ambient light level is an unacceptable ambient light level, a direction to move the display device.

2. The method of claim 1, wherein the visual representation of whether the ambient light level is acceptable for display screen operation is updated in real-time.

3. The method of claim 1, wherein the visual representation comprises a map of relative ambient light intensities across the display screen.

4. The method of claim 3, wherein the visual representation is color-coded, and wherein a color in the visual representation represents a relative ambient light level.

5. The method of claim 1, further comprising providing a visual indicator of the direction to move the display device to correct for the unacceptable ambient light level.

6. The method of claim 5, wherein the direction to move the display device is determined by determining a plurality of gradients of ambient intensities on the display screen, and generating a directional vector from the gradients.

7. A method of installing an optical touch-sensitive device, the optical touch-sensitive device comprising a display screen, an illuminant configured to illuminate a backside of the display screen, and an image sensor configured to capture an image of a backside of the display screen, the method comprising:

illuminating the display screen with the illuminant while measuring a first gray level value with a black screen located on the display screen, and while measuring a second gray level value with a white screen located on the display screen;

computing a threshold level value using the first and second gray level values;

capturing an image of the display screen;

determining a level of ambient light in the image;

comparing the level of ambient light on the screen with the threshold level value; and

providing a visual representation of whether the ambient light level is acceptable for display screen operation based upon the comparison with the threshold level value.

8. The method of claim 7, wherein the image of the display screen is captured while the display screen is free of objects located on the screen.

9. The method of claim 7, wherein comparing the level of ambient light on the screen with the threshold level value further comprises:

comparing if the ambient light level is more than a selected amount above the threshold level value or more than a selected amount below the threshold level value; and

displaying a first visual representation of an ambient light level more the selected amount above the threshold level value, a second visual representation of an ambient light level more than the selected amount below the threshold level value, and a third visual representation if the ambient light level is not more than the selected amount above the threshold level value and not more than the selected amount below the threshold level value.

10. The method of claim 9, wherein the selected amount above the threshold level value comprises a percentage within a range of 5-15 percent.

11. The method of claim 7, wherein capturing an image of the display screen comprises capturing an image of the display screen while the illuminant is illuminating the display screen.

12. The method of claim 7, wherein the visual representation is displayed via a map of ambient light levels on the display screen or a bar graph of an ambient light level on the display screen.

13. The method of claim 7, wherein the visual representation is configured to update in real-time.

14. The method of claim 7, wherein the threshold level value comprises a value within a range of 15-25 percent above the gray level value measured with the black screen.

15. The method of claim 7, wherein computing the threshold level value comprises setting the threshold level value to a saturation ambient light level for the image sensor.