SYSTEM AND METHOD FOR MOTION DETECTION IN A SURVEILLANCE VIDEO

• US 20140198257A1
• Filed: 10/28/2013
• Published: 07/17/2014
• Est. Priority Date: 04/22/2009
• Status: Active Grant

• Current Assignee: CheckVideo, LLC (Kastle Systems International LLC)
• Original Assignee: CheckVideo, LLC (Kastle Systems International LLC)
• Inventors: Gagvani, Nikhil, Gritai, Alexei
• Granted Patent: US 9,230,175 B2
• Time in Patent Office: Days
• US Class Current: 348/700
• CPC Class Codes: G06F 2218/14 by matching peak patterns
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 7/194 involving foreground-background segmentation
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06V 20/49 Segmenting video sequences, i.e. computational techniques such as parsing or cutting the sequence, low-level clustering or determining units such as shots or scenes
• CPC Class Codes: H04N 5/91 Television signal processing therefor

Abstract

In some embodiments, a non-transitory processor-readable medium stores code representing instructions to cause a processor to smooth a current image of a scene to produce a smoothed image and subtract pixel values of a background image of the scene from corresponding pixel values of the smoothed image to produce an altitude difference image. Pixel values of the altitude difference image are weighted to produce a weighted difference image. The weighted difference image is convolved to produce a convoluted difference image. A threshold is applied to each pixel of the convoluted difference image to produce a thresholded difference image. Pixels having a value less than the threshold are removed from the thresholded difference image and classified as background pixels. Foreground pixels are determined based on the thresholded difference image.

Claims

1. A non-transitory processor-readable medium storing code representing instructions to be executed by a processor, the code comprising code to cause the processor to:

receive video data having a plurality of pixels;

classify each pixel from a plurality of pixels associated with an image as a foreground pixel or a background pixel using a threshold from a plurality of first thresholds and associated with that pixel, and a threshold from a plurality of second thresholds and associated with that pixel;

reset a value of a first threshold from the plurality of first thresholds associated with a first pixel from the plurality of pixels to a default first threshold value, the first pixel being classified as a foreground pixel;

update a value of a second threshold from the plurality of first thresholds associated with a second pixel from the plurality of pixels, the second pixel being classified as a background pixel, a first counter configured to count the number of successive frames the second pixel is classified as a background pixel having a value greater than a counter threshold; and

incrementing a second counter configured to count the number of successive frames a third pixel from the plurality of pixels is classified as a background pixel, the third pixel being classified as a background pixel, the second counter having a value less than the counter threshold, a third threshold from the plurality of first thresholds associated with the third pixel maintaining its value.

2. The non-transitory processor-readable medium of claim 1, further comprising code to cause the processor to:

reset a value of the threshold from the plurality of second thresholds associated with the first pixel from the plurality of pixels to a default second threshold value.

3. The non-transitory processor-readable medium of claim 1, further comprising code to cause the processor to:

reset a value of a first threshold from the plurality of second thresholds associated with the first pixel to a default second threshold value; and

update a value of a second threshold from the plurality of second thresholds associated with the second pixel.

4. The non-transitory processor-readable medium of claim 1, wherein the code to cause the processor to update the value of the second threshold from the plurality of first thresholds includes code to cause the processor to update the value of the second threshold based on a brightness of the second pixel and a background difference of the second pixel.

5. The non-transitory processor-readable medium of claim 1, wherein the image is a convoluted difference image, the code further comprising code to cause the processor to:

subtract pixel values of a background image of a scene from corresponding pixel values of a smoothed image of the scene to produce an altitude difference image;

weight each pixel value of the altitude difference image to produce a weighted difference image; and

convolve the weighted difference image to produce the convoluted difference image.

6. The non-transitory processor-readable medium of claim 1, wherein the value of the first threshold from the plurality of first thresholds is greater than a value of a threshold from the plurality of second thresholds associated with the first pixel.

7. The non-transitory processor-readable medium of claim 1, wherein the default first threshold value is associated with the first pixel, the code further comprising code to cause the processor to:

update a default first threshold value associated with the second pixel; and

maintain a default first threshold value associated with the third pixel.

8. A non-transitory processor-readable medium storing code representing instructions to be executed by a processor, the code comprising code to cause the processor to:

receive video data having a plurality of pixels;

classify each pixel from the plurality of pixels associated with an image as a foreground pixel or a background pixel using a low threshold from a plurality of low thresholds and associated with that pixel, and a high threshold from a plurality of high thresholds and associated with that pixel;

reset a value of the low threshold from the plurality of low thresholds and associated with a first pixel from the plurality of pixels to a predetermined low threshold value when the first pixel is classified as a foreground pixel; and

update (1) a value of the low threshold from the plurality of low thresholds and associated with a second pixel from the plurality of pixels, and (2) a value of the high threshold from the plurality of high thresholds and associated with the second pixel, when the second pixel is classified as a background pixel for a number of successive frames greater than a predetermined counter threshold.

9. The non-transitory processor-readable medium of claim 8, the code further comprising code to cause the processor to:

reset a value of the high threshold from the plurality of high thresholds and associated with the first pixel from the plurality of pixels to a predetermined high threshold value.

10. The non-transitory processor-readable medium of claim 8, wherein the code to cause the processor to reset the value of the low threshold associated with the first pixel includes code to cause the processor to reset the value of the low threshold associated with the first pixel based on at least one of a brightness of the first pixel or a background difference of the first pixel.

11. The non-transitory processor-readable medium of claim 8, wherein the code to cause the processor to update the value of the low threshold associated with the second pixel includes code to cause the processor to update the value of the low threshold associated with the second pixel based on at least one of a brightness of the second pixel or a background difference of the second pixel.

12. The non-transitory processor-readable medium of claim 8, wherein the image is a convoluted difference image, the code further comprising code to cause the processor to:

subtract pixel values of a background image of a scene from corresponding pixel values of a smoothed image of the scene to produce an altitude difference image;

weight each pixel value of the altitude difference image to produce a weighted difference image; and

convolve the weighted difference image to produce the convoluted difference image.

13. The non-transitory processor-readable medium of claim 8, the code further comprising code to cause the processor to:

maintain a value of a low threshold from the plurality of low thresholds and associated with a third pixel from the plurality of pixels when the third pixel is classified as a background pixel for a number of successive frames less than or equal to the predetermined counter threshold.

14. A non-transitory processor-readable medium storing code representing instructions to be executed by a processor, the code comprising code to cause the processor to:

receive video data having a plurality of pixels

classify a pixel from the plurality of pixels associated with an image as a background pixel, the pixel being associated with a threshold from a plurality of first thresholds and a threshold from a plurality of second thresholds; and

update at least one of a value of the threshold from the plurality of first thresholds or a value of the threshold from the plurality of second thresholds when the pixel is classified as a background pixel for a number of successive frames that is greater than a value of a counter threshold.

15. The non-transitory processor-readable medium of claim 14, wherein the pixel is a first pixel, the threshold from the plurality of first thresholds is a first threshold from the plurality of first thresholds, the threshold from the plurality of second thresholds is a first threshold from the plurality of second thresholds, the code further comprising code to cause the processor to:

classify a second pixel from the plurality of pixels as a foreground pixel, the second pixel being associated with a second threshold from the plurality of first thresholds and a second threshold from the plurality of second thresholds; and

reset at least one of (1) a value of the second threshold from the plurality of first thresholds to a predetermined first threshold value, or (2) a value of the second threshold from the plurality of second thresholds to a predetermined second threshold value.

16. The non-transitory processor-readable medium of claim 14, wherein the code to cause the processor to update at least one of the value of the threshold from the plurality of first thresholds or the value of the threshold from the plurality of second thresholds includes code to cause the processor to update at least one of the value of the threshold from the plurality of first thresholds or the value of the threshold from the plurality of second thresholds based on a brightness of the pixel and a background difference of the pixel.

17. The non-transitory processor-readable medium of claim 14, wherein the image is a convoluted difference image, the code further comprising code to cause the processor to:

subtract pixel values of a background image of a scene from corresponding pixel values of a smoothed image of the scene to produce an altitude difference image;

weight each pixel value of the altitude difference image to produce a weighted difference image; and

convolve the weighted difference image to produce the convoluted difference image.

18. The non-transitory processor-readable medium of claim 14, wherein the pixel is a first pixel, the threshold from the plurality of first thresholds is a first threshold from the plurality of first thresholds, the threshold from the plurality of second thresholds is a first threshold from the plurality of second thresholds, the code further comprising code to cause the processor to:

update at least one of a value of a second threshold from the plurality of first threshold values and associated with a second pixel from the plurality of pixels or a value of a second threshold value from the plurality of second threshold values and associated with the second pixel when the second pixel is classified as a background pixel for a number of successive frames that is greater than the value of the counter threshold; and

maintain at least one of a value of a third threshold from the plurality of first threshold values and associated with a third pixel from the plurality of pixels or a value of a third threshold from the plurality of second threshold values and associated with the third pixel when the third pixel is classified as a background pixel for a number of successive frames that is less than or equal to the value of the counter threshold.

19. The non-transitory processor-readable medium of claim 14, wherein the code to cause the processor to classify the pixel as a background pixel includes code to cause the processor to classify the pixel as a background pixel at a first time, the code further comprising code to cause the processor to:

classify, at a second time after the first time, the pixel as a foreground pixel; and

reset, in response to the pixel being classified as a foreground pixel, at least one of the value of the threshold from the plurality of first thresholds to a predetermined threshold value or the value of the threshold from the plurality of second thresholds to a predetermined second threshold value.

20. The non-transitory processor-readable medium of claim 14, wherein the code to cause the processor to classify the pixel as a background pixel includes code to cause the processor to classify the pixel as a background pixel at a first time, the code further comprising code to cause the processor to:

classify, at a second time after the first time, the pixel as a foreground pixel; and

reset, in response to the pixel being classified as a foreground pixel, a counter configured to count the number of successive frames the pixel is classified as a background pixel, to a predetermined counter value.