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Surveillance video based video foreground extraction method

  • US 10,395,374 B2
  • Filed: 04/06/2017
  • Issued: 08/27/2019
  • Est. Priority Date: 06/27/2016
  • Status: Active Grant
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First Claim
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1. A surveillance video based video foreground extraction method which adjusts a size of a block to adapt to different video resolutions extracts a foreground object in a moving state, the method comprising the following steps:

  • step 1;

    representing each frame of an image I in the surveillance video as the block and representing the image I as a matrix block I′

    ;

    step 2;

    initializing for a first frame of the image I a temporary background β and

    a background B with the image I, wherein a temporary foreground is represented with a zero matrix γ

    with the size of P*Q, a foreground is represented with a matrix F and initialized with the zero matrix, a block background A and a temporary block background α

    are initialized with a matrix I′

    , a background block weight is represented with a zero matrix ψ

    with the size of m*n, a foreground block weight is represented with φ and

    initialized with the zero matrix, and a foreground block end is represented with ω and

    initialized with the zero matrix;

    step 3;

    setting an s and a t to represent respective rows and columns of a matrix block, comparing an element bs,tI′

    i in a matrix block I′

    i in a next frame of the image I with a corresponding element bs,tI′

    i-1 in a previous frame of the image I to obtain a difference |bs,tI′

    i−

    bs,tI′

    i-1|, and setting a threshold ε

    1, wherein if |bs,tI′

    i−

    bs,tI′

    i-1|<

    ε

    1, a block background weight ψ

    s,t is auto-increased by 1;

    otherwise the block background weight ψ

    s,t is reset to be 0, and a block temporary background and the temporary background are updated;

    step 4;

    representing a duration that a block stream remains unchanged with a set threshold ε

    2, wherein if the value of a block background image weight exceeds the threshold ε

    2, the block background is updated with the temporary block background, and the background is updated with the temporary background;

    step 5;

    when the difference between a current block and a background block exceeds the threshold ε

    1 or the background block weight is 0, executing step 6;

    otherwise, executing step 3;

    step 6;

    comparing pixels in the current block with pixels in a block corresponding to a background frame, wherein if a pixel difference exceeds a number of pixels of a threshold ε

    3, that is, half of the number of pixels in the block, executing step 7;

    otherwise, executing step 3;

    step 7;

    saving the difference between a pixel value in the image I and the pixel value corresponding to the background B as a foreground F, wherein if the foreground block is continuous and the difference between current and previous foreground blocks is less than the threshold ε

    1, the foreground block weight is auto-increased by 1 and the foreground blocks are weighted and averaged;

    step 8;

    if the value of a block foreground image weight exceeds the threshold ε

    2, updating the background B, the block background A, and the temporary block background α

    with the temporary foreground, resetting the block background weight to be the threshold ε

    2, and setting the temporary foreground γ

    as 0;

    step 9;

    binarizing the foreground F obtained in step 7 to obtain a final foreground result, and saving a current frame number as a foreground end ω

    s,t; and

    step 10;

    repeating steps 3-9 until all frames of the image I in the video are processed so as to obtain a video foreground through extraction.

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