Moving object detection method and system

1. A moving object detection method, comprising:

predetermining a background image corresponding to a scene monitored by a video monitoring device;

performing a subtraction processing on a grayscale image to be detected and the background image to acquire a difference image; and

binarizing the difference image and determining a moving object in the grayscale image to be detected,

wherein the determining the background image comprises:

dividing the first grayscale image frame into K image blocks which do not overlap with each other and include all pixels in the first grayscale image frame, to acquire the first image block set, and dividing the second grayscale image frame into K image blocks which do not overlap with each other and include all pixels in the second grayscale image frame, to acquire the second image block set, wherein K is a positive integer, the image blocks have the same size, and the K image blocks in the first image block set have a one-to-one correspondence with the K image blocks in the second image block set,

calculating the difference between the first image block set and the second image block set, and

acquiring the background image using the difference and the first image block set.

2. The moving object detection method according to claim 1 , wherein a time instant at which the grayscale image to be detected is captured is greater than or equal to a time instant at which the first grayscale image frame is captured, the time instant at which the first grayscale image frame is captured is greater than a time instant at which the second grayscale image frame is captured, and there are N grayscale image frames between the first grayscale image frame and the second grayscale image frame, wherein N is a positive integer.

3. The moving object detection method according to claim 1 , wherein the calculating the difference between the first image block set and the second image block set comprises:

calculating an image block grayscale difference between each image block in the first image block set and a corresponding image block in the second image block set, to acquire an image block grayscale difference set, wherein an i-th element in the image block grayscale difference set is calculated according to an equation:

d i =|g t,i −g t−N,i |,

wherein g t,i represents an i-th image block in the first image block set, which is represented by g t , g t−N,i represents an i-th image block in the second image block set, which is represented by g t−N , and d i represents an image block grayscale difference between the i-th image block in the first image block set and the i-th image block in the second image block set, wherein Z=1, 2, . . . , K; and

calculating a difference between each image block in the first image block set and a corresponding image block in the second image block set using the image block grayscale difference set to acquire a difference set, wherein an i-th element in the difference set is calculated according to an equation:

s

i

=

∑

1

≤

x

≤

n

,

1

≤

y

≤

m

⁢

⁢

d

i

⁡

(

x

,

y

)

,

wherein n represents the length of each image block, m represents the width of each image block, both n and m are in units of pixels, d i (x, y) represents a grayscale difference in d i corresponding to an (x, y)-th pixel in the image block, and s i represents a difference between an i-th image block in the first image block set and an i-th image block in the second image block set.

4. The moving object detection method according to claim 3 , wherein the acquiring the background image using the difference and the first image block set comprises:

converting the difference set to a determination set using a preset conversion equation:

w

i

=

{

1

,

s

i

≤

TH

1

0

,

else

,

wherein TH 1 represents a preset difference threshold, and w i represents an i-th determination element in the determination set; and

inputting the determination set and the first image block set into a preset first background image construction equation to acquire the background image, wherein the first background image construction equation is expressed as:

b

i

=

{

g

t

,

i

,

w

i

=

1

b

i

′

,

w

i

=

0

,

wherein b i represents an i-th image block in the background image, and b′ i represents an i-th image block in a previous background image.

5. The moving object detection method according to claim 3 , wherein the acquiring the background image using the difference and the first image block set comprises:

inputting the difference set and the first image block set into a preset second background image construction equation to acquire the background image, wherein the second background image construction equation is expressed as:

⁢

b

i

=

{

g

t

,

i

,

s

i

≤

TH

1

b

i

′

,

else

,

wherein TH 1 represents a preset difference threshold, b i represents an i-th image block in the background image, and b′ i represents an i-th image block in a previous background image.

6. The moving object detection method according to claim 4 , wherein in a case that the previous background image is a first background image, the first background image is an image in which grayscale values of all pixels are 0.

7. The moving object detection method according to claim 4 , wherein the binarizing the difference image and determining the moving object in the grayscale image to be detected comprises:

binarizing the difference image using a preset binarization processing equation to acquire a binarized image, wherein the binarization processing equation is expressed as:

F

′

⁡

(

p

,

q

)

=

{

0

,

F

⁡

(

p

,

q

)

≤

TH

2

255

,

else

,

wherein TH 2 represents a preset grayscale threshold, F(p,q) represents a grayscale value corresponding to a (p,q)-th pixel in the difference image, which is represented by F, and F′(p,q) represents a grayscale value corresponding to a (p,q)-th pixel in the binarized image; and

extracting pixels of which grayscale values are 255 from the binarized image to acquire the moving object in the grayscale image to be detected.

8. A moving object detection system, comprising:

a background image determination module, configured to predetermine a background image corresponding to a scene monitored by a video monitoring device;

a difference image acquisition module, configured to perform a subtraction processing on a grayscale image to be detected and the background image to acquire a difference image; and

a moving object determination module, configured to binarize the difference image and determine a moving object in the grayscale image to be detected, wherein the background image determination module being configured to determine the background image comprises:

the background image determination module being configured to

divide the first grayscale image frame into K image blocks which do not overlap with each other and include all pixels in the first grayscale image frame, to acquire the first image block set, and divide the second grayscale image frame into K image blocks which do not overlap with each other and include all pixels in the second grayscale image frame, to acquire the second image block set, wherein K is a positive integer, the image blocks have the same size, and the K image blocks in the first image block set have a one-to-one correspondence with the K image blocks in the second image block set,

calculate the difference between the first image block set and the second image block set, and

acquire the background image using the difference and the first image block set.

9. The moving object detection method according to claim 5 , wherein in a case that the previous background image is a first background image, the first background image is an image in which grayscale values of all pixels are 0.

10. The moving object detection method according to claim 5 , wherein the binarizing the difference image and determining the moving object in the grayscale image to be detected comprises:

binarizing the difference image using a preset binarization processing equation to acquire a binarized image, wherein the binarization processing equation is expressed as:

F

′

⁡

(

p

,

q

)

=

{

0

,

F

⁡

(

p

,

q

)

≤

TH

2

255

,

else

,

wherein TH 2 represents a preset grayscale threshold, F(p,q) represents a grayscale value corresponding to a (p,q)-th pixel in the difference image, which is represented by F, and F′(p,q) represents a grayscale value corresponding to a (p,q)-th pixel in the binarized image; and

extracting pixels of which grayscale values are 255 from the binarized image to acquire the moving object in the grayscale image to be detected.