Automatic gain control filter in a video analysis system

摘要

Techniques are disclosed for analyzing a scene depicted in an input stream of video frames captured by a video camera. Bounding boxes are determined for a set foreground patches identified in a video frame. For each bounding box, the techniques include determining textures for first areas, each including a foreground pixel and surrounding pixels, and determining textures for second areas including pixels of the background model image corresponding to the pixels of the foreground areas. Further, for each foreground pixel in the bounding box area, a correlation score is determined based on the texture of the corresponding first area and second area. Pixels whose correlation scores exceed a threshold are removed from the foreground patch. The size of the bounding box may also be reduced to fit the modified foreground patch.

主权项

1. A computer-implemented method for filtering out false-positive foreground pixels, the method comprising:
extracting foreground patches from a video frame using a background model image, the foreground patches each including respective foreground pixels; determining a bounding box for each foreground patch; for each bounding box:
(1) for each foreground pixel in the foreground patch in the bounding box:
(A) determining a texture of a first area including the foreground pixel and pixels surrounding the foreground pixel and a texture of a second area including pixels of the background model image corresponding to the first area pixels, wherein the textures of the first area and the second area each represent a local variability of intensity values of respective pixels, and(B) determining a correlation score based on the texture of the first area and the texture of the second area, and(2) for foreground pixels having correlation scores which exceed a threshold value, removing the foreground pixels from the foreground patch in the bounding box, wherein the threshold value is proportional to a size of the bounding box; and for each bounding box having foreground pixels removed, reducing a size of the bounding box based on the removal of the foreground pixels.