Image surveillance system and image surveillance method

1. An image surveillance method suitable for an image surveillance system, the image surveillance method comprising:

capturing an image;

defining at least one reference target in the captured image;

identifying a monitored object in the image;

individually calculating a distance between the monitored object and each of the at least one reference target; and

determining whether to announce at least one warning according to a relationship between at least one threshold and the distance,

wherein the step of determining whether to announce the at least one warning according to the relationship between the at least one threshold and the distance comprises:

calculating a function; and

determining whether to announce the at least one warning according to a relationship between the at least one threshold and the function, wherein the function is

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,

D i is a distance from the monitored object to an i th reference target of the at least one reference target, a i and b i are real numbers, k is a real number larger than

-

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and n is a quantity of the at least one reference target.

2. The image surveillance method as recited in claim 1 , wherein the at least one reference target comprises at least one of a point, a line, and an area in the image.

3. The image surveillance method as recited in claim 1 , wherein the step of identifying the monitored object in the image comprises:

comparing the image with an initial image; and

identifying a difference between the image and the initial image as the monitored object.

4. The image surveillance method as recited in claim 1 , wherein the at least one threshold comprises a first threshold and a second threshold smaller than the first threshold, and the step of determining whether to announce the at least one warning according to the relationship between the at least one threshold and the function comprises:

determining a relationship between the function and the first and second thresholds;

announcing a first warning if the function is larger than the second threshold and is smaller than the first threshold; and

announcing a second warning if the function is smaller than or equal to the second threshold.

5. The image surveillance method as recited in claim 1 , wherein the at least one threshold comprises a first threshold and a second threshold larger than the first threshold, and the step of determining whether to announce the at least one warning according to the relationship between the at least one threshold and the function comprises:

determining a relationship between a reciprocal of the function and the first and second thresholds;

announcing a first warning if the reciprocal of the function is between the first threshold and the second threshold; and

announcing a second warning if the reciprocal of the function is larger than or equal to the second threshold.

6. An image surveillance system comprising:

an image capturing apparatus capturing an image; and

an image processing apparatus coupled to the image capturing apparatus and configured to:

define at least one reference target in the captured image;

identify a monitored object in the image;

individually calculate a distance between the monitored object and each of the at least one reference target; and

determine whether to announce at least one warning according to a relationship between at least one threshold and the distance,

wherein the image processing apparatus is configured to:

calculate a function; and

determine whether to announce the at least one warning according to a relationship between the at least one threshold and the function, wherein the function is

∑

i

=

1

n

⁢

⁢

(

a

i

⁢

D

i

b

i

)

+

k

,

D i is a distance from the monitored object to an i th reference target of the at least one reference target, a, and b, are real numbers, k is a real number larger than

-

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i

=

1

n

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a

i

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D

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b

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,

and n is a quantity of the at least one reference target.

7. The image surveillance system as recited in claim 6 , wherein the at least one reference target comprises at least one of a point, a line, and an area in the image.

8. The image surveillance system as recited in claim 6 , wherein the image processing apparatus is configured to:

compare the image with an initial image; and

identify a difference between the image and the initial image as the monitored object.

9. The image surveillance system as recited in claim 6 , wherein the at least one threshold comprises a first threshold and a second threshold smaller than the first threshold, and the image processing apparatus is configured to:

determine a relationship between the function and the first and second thresholds;

announce a first warning if the function is larger than the second threshold and is smaller than the first threshold; and

announce a second warning if the function is smaller than or equal to the second threshold.

10. The image surveillance system as recited in claim 6 , wherein the at least one threshold comprises a first threshold and a second threshold larger than the first threshold, and the image processing apparatus is configured to:

determine a relationship between a reciprocal of the function and the first and second thresholds;

announce a first warning if the reciprocal of the function is between the first threshold and the second threshold; and

announce a second warning if the reciprocal of the function is larger than or equal to the second threshold.