Automatic gain control filter in a video analysis system

A non-transitory computer-readable storage medium storing instructions, which when executed by a computer system, perform operations for filtering out false-positive foreground pixels, the operations 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.

A system, comprising:

• a processor;
• and
• a memory, wherein the memory includes an application program configured to perform operations for filtering out false-positive foreground pixels, the operations 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.