Image-based visibility measurement

• US 7,602,937 B2
• Filed: 06/08/2005
• Issued: 10/13/2009
• Est. Priority Date: 06/08/2004
• Status: Active Grant

• Current Assignee: International Electronic Machines Corp.
• Original Assignee: International Electronic Machines Corp.
• Inventors: vonAchen, William G., Mian, Zahid F.
• Primary Examiner(s): Johns; Andrew W
• Application Number:
  US11/149,089
• Publication Number:
  US 20050270537A1
• Time in Patent Office: 1,588 Days
• Field of Search: 346/4.07, 346/456, 346/482, 382/106, 382/199, 382/100, 382/286, 356/432, 356/433, 356/434, 356/436, 356/437, 340/601, 702/3, 731/701.6, 731/702.7
• US Class Current: 382/100
• CPC Class Codes: G01N 21/538 for determining atmospheric attenuation and visibility
• CPC Class Codes: G06T 7/00 Image analysis

Abstract

The invention provides an image-based visibility measurement solution in which an image is used to calculate a visibility (visual range). In one embodiment, a lighting condition for the image is determined and the visibility calculation is adjusted based on the lighting condition. Further, the invention can obtain image data for a set of portions of the image and estimate a visual range based on each portion. The estimated visual ranges can be combined to calculate the visibility for the image. Still further, multiple metrics can be calculated, each of which is used to estimate a visual range. Subsequently, the visual ranges can be used to calculate the visibility for the image. Even further, configuration data that is based on a set of training images can be used to calculate the visibility for a new image. To this extent, the invention can incorporate the lighting condition, portions of the image having differing features, multiple metrics, and/or feedback through training images to accurately measure visibility based on an image.

Claims

1. A system for measuring visibility, the system comprising:

means for determining a lighting condition for an image;

means for calculating a visibility based on the image; and

means for adjusting the means for calculating based on the lighting condition, wherein the means for adjusting selects any one of;

a set of visibility calculations for a daytime lighting condition, a set of visibility calculations for a nighttime lighting condition, or a set of visibility calculations comprising at least one calculation for a daytime lighting condition and at least one calculation for a nighttime lighting condition according to the lighting condition, and wherein the means for calculating calculates the visibility using the selected set of visibility calculations.

2. The system of claim 1, further comprising means for selecting a field of view for the image.

3. The system of claim 1, further comprising means for capturing the image.

4. The system of claim 3, wherein the means for capturing further includes means for filtering undesired wavelengths of light from the image.

5. The system of claim 1, wherein the image is based on light in the visible and near-infrared spectrums.

6. The system of claim 1, wherein the means for determining includes means for analyzing the image.

7. The system of claim 1, wherein the means for calculating includes:

means for obtaining image data for a plurality of portions of the image;

means for estimating a plurality of visual ranges using the selected set of visibility calculations, wherein each estimated visual range is based on image data for a unique one of the plurality of portions; and

means for calculating the visibility based on the plurality of visual ranges.

8. The system of claim 7, wherein the means for estimating includes:

means for calculating a plurality of metrics based on the image data for the unique one of the plurality of portions;

means for estimating a plurality of metric-based visual ranges, wherein each of the plurality of metric-based visual ranges is based on a unique one of the plurality of metrics; and

means for estimating the visual range for the one of the plurality of portions based on the plurality of metric-based visual ranges.

9. A system comprising:

means for obtaining image data for a plurality of portions of an image; and

means for estimating a unique visual range for each of the plurality of portions of the image, wherein each visual range is estimated based on a set of features detected in the image data for at least one of;

a set of target objects or a set of light sources in a unique one of the plurality of portions.

10. The system of claim 9, further comprising means for identifying the plurality of portions in the image.

11. The system of claim 9, further comprising means for selecting the plurality of portions based on a lighting condition for the image.

12. The system of claim 9, further comprising means for calculating the visibility based on a combination of the plurality of visual ranges.

13. A system for measuring visual ranges, the system comprising:

means for obtaining image data for a plurality of portions of an image; and

means for estimating a plurality of visual ranges, wherein each estimated visual range is based on the image data for a unique one of the plurality of portions, and wherein the means for estimating includes;

means for calculating a plurality of metrics based on the image data for the one of the plurality of portions;

means for estimating a plurality of metric-based visual ranges, wherein each of the plurality of metric-based visual ranges is based on one of the plurality of metrics; and

means for estimating the visual range for the one of the plurality of portions based on the plurality of metric-based visual ranges.

14. A system for measuring visibility, the system comprising:

means for calculating a plurality of metrics based on an image;

means for estimating a plurality of visual ranges, wherein each of the plurality of visual ranges is based on a unique one of the plurality of metrics; and

means for calculating the visibility based on the plurality of visual ranges.

15. The system of claim 14, further comprising means for selecting the plurality of metrics based on a lighting condition for the image.

16. The system of claim 15, further comprising means for determining the lighting condition for the image.

17. The system of claim 14, wherein the plurality of metrics include at least one metric based on a pixel intensity for at least a portion of the image.

18. The system of claim 14, wherein the plurality of metrics include at least one metric based on a contrast between a target object in the image and a background.

19. The system of claim 14, wherein the plurality of metrics include at least one metric based on edges detected in at least a portion of the image.

20. The system of claim 14, wherein the plurality of metrics include at least one metric based on a wavelet transform of image data for at least a portion of the image.

21. The system of claim 14, wherein the plurality of metrics include at least one metric based on a number of light sources in at least a portion of the image.

22. The system of claim 14, wherein the plurality of metrics include at least one metric based on a color intensity for at least a portion of the image.

23. A system for measuring visibility, the system comprising:

means for obtaining configuration data, wherein the configuration data is based on a set of training images, and wherein the configuration data includes a visibility curve for each unique combination of a metric and a portion of an image in the set of training images;

means for obtaining a new image; and

means for calculating the visibility based on the configuration data and the new image.

24. The system of claim 23, further comprising means for selecting the configuration data based on a lighting condition for the image.

25. The system of claim 23, wherein the means for calculating includes:

means for obtaining image data for a plurality of portions of the image;

means for estimating a plurality of visual ranges, wherein each estimated visual range is based on image data for one of the plurality of portions and at least one corresponding visibility curve for the one of the plurality of portions; and

means for calculating the visibility based on the plurality of visual ranges.

26. The system of claim 23, wherein the means for calculating includes:

means for calculating a plurality of metrics based on image data for at least a portion of the image;

means for estimating a plurality of metric-based visual ranges, wherein each of the plurality of metric-based visual ranges is based on one of the plurality of metrics; and

means for calculating the visibility based on the plurality of metric-based visual ranges.

27. The system of claim 23, further comprising means for comparing the new image to the set of training images.

28. The system of claim 23, further comprising means for adding the new image to the set of training images when the new image is sufficiently different from each training image in the set of training images.

29. The system of claim 28, further comprising means for updating the configuration data based on the new image.

30. The system of claim 23, further comprising means for periodically removing a training image from the set of training images.