Method of controlling panning and tilting of surveillance camera using edge value

1. A method of controlling a surveillance camera, the method comprising:

selecting at least one pixel in a reference image, based on edge values of pixels in the reference image of a surveillance region;

detecting at least one pixel in an object-captured image, based on edge values of pixels in the object-captured image, which is captured after at least one of panning and tilting is completed to the surveillance region; and

correcting the at least one of the panning and the tilting in the object-captured image by moving the at least one pixel in the object-captured image to a reference location of the at least one pixel in the reference image.

2. The method of claim 1 ,

wherein:

the detecting the at least one pixel in an object-captured image comprises:

obtaining an edge value with respect to each pixel of the object-captured image of a panning-completed time, wherein the edge value is a difference between brightness of a left adjacent pixel thereof and brightness of a right adjacent pixel thereof; and

obtaining an object vertical-line number which is a number of a vertical pixel line in which a sum of the edge values is largest among vertical pixel lines of the object-captured image; and

the correcting the at least one of the panning and the tilting comprises correcting the panning in the object-captured image by moving the object vertical-line to a reference vertical-line obtained by the at least one pixel selected in the reference image.

3. The method of claim 1 ,

wherein:

the detecting the at least one pixel in an object-captured image comprises:

obtaining an edge value with respect to each pixel of a plurality of preset partial blocks of the object-captured image of a panning-completed time, wherein the edge value is a difference between brightness of a left adjacent pixel thereof and brightness of a right adjacent pixel thereof; and

obtaining an object vertical-line with respect to each of the plurality of preset partial blocks, the object vertical-line being a vertical pixel line in which a sum of the edge values is largest among vertical pixel lines; and

the correcting the at least one of the panning and tilting comprises correcting the panning in the object-captured image by moving the object vertical-line to a reference vertical-line obtained by the at least one pixel selected with respect to a preset number of partial blocks among the plurality of partial blocks of the reference image.

4. The method of claim 3 , further comprising:

dividing the reference image into the plurality of partial blocks, and classifying the plurality of partial blocks into central partial blocks and peripheral partial blocks;

obtaining an edge value with respect to each pixel of the reference image of the panning-completed time, wherein the edge value is a difference between brightness of a left adjacent pixel thereof and brightness of a right adjacent pixel thereof;

calculating a sum of the edge values of each of the peripheral partial blocks while giving a high weight rate as a location of the peripheral partial blocks approaches an outermost part; and

setting the preset number of partial blocks in an order based on the sum of the edge values from high to low among the peripheral partial blocks.

5. The method of claim 1 , further comprising:

when the panning is completed, obtaining values of automatic exposure parameters which have been applied to an object-captured image,

wherein:

the detecting the at least one pixel in an object-captured image comprises:

when an average deviation of the values of the automatic exposure parameters and reference values is less than an upper limit value, obtaining an edge value with respect to each pixel of the object-captured image, wherein the edge value is a difference between brightness of a left adjacent pixel thereof and brightness of a right adjacent pixel thereof; and

obtaining an object vertical-line which is a vertical pixel line in which a sum of the edge values is largest among vertical pixel lines of the object-captured image; and

the correcting the at least one of the panning and the tilting comprises correcting the panning in the object-captured image by moving the object vertical-line to a reference vertical-line obtained by the at least one pixel selected in the reference image.

6. The method of claim 1 , further comprising:

obtaining an object pan angle by using a photo interrupter sensor assembly, wherein the object pan angle is an actual pan angle of a panning-completed time, when the panning is completed to the surveillance region; and

when a difference between the object pan angle and the set angle exceeds a reference limit, performing first correction of the panning such that the object pan angle coincides with the set angle

wherein:

the detecting the at least one pixel in an object-captured image comprises:

obtaining an edge value with respect to each pixel of the object-captured image, wherein the edge value is a difference between brightness of a left adjacent pixel thereof and brightness of a right adjacent pixel thereof; and

obtaining an object vertical-line which is a vertical pixel line in which sum of the edge values is largest among vertical pixel lines of the object-captured image; and

the correcting the at least one of the panning and tilting comprises performing second correction of the panning in the object-captured image by moving the object vertical-line to a reference vertical-line obtained by the at least one pixel selected in the reference image.

7. The method of claim 1 , further comprising:

wherein:

the detecting the at least one pixel in an object-captured image comprises:

obtaining an edge value with respect to each pixel of the object-captured image of a tilting-completed time, wherein the edge value is a difference between brightness of an upper adjacent pixel thereof and brightness of a lower adjacent pixel thereof; and

obtaining an object horizontal-line which is a horizontal pixel line in which a sum of the edge values is largest among horizontal pixel lines of the object-captured image; and

the correcting the at least one of the panning and the tilting comprises correcting the tilting in the object-captured image by moving the object horizontal-line to a reference horizontal-line obtained by the at least one pixel selected in the reference image.

8. The method of claim 1 ,

wherein:

the detecting the at least one pixel in an object-captured image comprises:

obtaining an edge value with respect to each pixel of a plurality of preset partial blocks of the object-captured image of a tilting-completed time, wherein the edge value is a difference between brightness of an upper adjacent pixel thereof and brightness of a lower adjacent pixel thereof; and

obtaining an object horizontal-line number with respect to each of the plurality of preset partial blocks, wherein the object horizontal-line is a horizontal pixel line in which a sum of the edge values is largest among horizontal pixel lines; and

the correcting the at least one of the panning and the tilting comprises correcting the tilting in the object-captured image by moving the object horizontal-line to a reference horizontal-line obtained by the at least one pixel selected with respect to a preset number of partial blocks among the plurality of partial blocks of the reference image.

9. The method of claim 8 , further comprising:

dividing the reference image into the plurality of partial blocks, and classifying the plurality of partial blocks into central partial blocks and peripheral partial blocks;

obtaining an edge value with respect to each pixel of the reference image, wherein the edge value is a difference between brightness of an upper adjacent pixel thereof and brightness of a lower adjacent pixel thereof;

calculating a sum of the edge values of each of the peripheral partial blocks while giving a high weight rate as a location of the peripheral partial blocks approaches an outermost part; and

setting the preset number of partial blocks in an order based on the sum of the edge values from high to low among the peripheral partial blocks.

10. The method of claim 1 , further comprising:

when the tilting is completed to the surveillance region, obtaining values of automatic exposure parameters which have been applied to an object-captured image,

wherein:

the detecting the at least one pixel in an object-captured image comprises:

when an average deviation of the values of the automatic exposure parameters and reference values is less than an upper limit value, obtaining an edge value with respect to each pixel of the object-captured image, wherein the edge value is a difference between brightness of an upper adjacent pixel thereof and brightness of a lower adjacent pixel thereof; and

obtaining an object horizontal-line which is a horizontal pixel line in which a sum of the edge values is largest among horizontal pixel lines of the object-captured image; and

the correcting the at least one of the panning and tilting comprises correcting the tilting in the object-captured image by moving the object horizontal-line to a reference horizontal-line obtained by the at least one pixel selected in the reference image.

11. The method of claim 1 , further comprising:

obtaining an object tilt angle by using a photo interrupter sensor assembly, the object tilt angle being an actual tilt angle of a tilting-completed time, when the tilting is completed to the surveillance region; and

when a difference between the object tilt angle and the set angle exceeds a reference limit, performing first correction of the tilting such that the object tilt angle coincides with the set angle,

wherein:

the detecting the at least one pixel in an object-captured image comprises:

obtaining an edge value with respect to each pixel of the object-captured image, wherein the edge value is a difference between brightness of an upper adjacent pixel thereof and brightness of a lower adjacent pixel thereof; and

obtaining an object horizontal-line which is a horizontal pixel line in which a sum of edge values is largest among horizontal pixel lines of the object-captured image; and

the correcting the at least one of the panning and tilting comprises performing second correction of the tilting in the object-captured image by moving the object horizontal-line to a reference horizontal-line obtained by the at least one pixel selected in the reference image.

12. The method of claim 1 ,

wherein:

the detecting the at least one pixel in an object-captured image comprises, when the panning and tilting are completed to the surveillance region, detecting an edge line by selecting the at least one pixel from the object-captured image; and

the correcting the at least one of the panning and tilting comprises correcting the panning and the tilting in the object-captured image by moving the detected edge line to a reference location of a reference edge line generated by selecting the at least one pixel in the reference image.

13. The method of claim 12 , further comprising:

after the panning and the tilting are corrected, periodically determining whether the edge line of the object-captured image deviates from the reference location; and

when the edge line of the object-captured image deviates from the reference location, correcting the panning and the tilting by moving the edge line to the reference location.

14. The method of claim 1 ,

wherein:

the detecting the at least one pixel in an object-captured image comprises, when the panning and the tilting are completed, detecting a pixel having a largest edge value from an object-captured image; and

the correcting the at least one of the panning and the tilting comprises correcting the panning and the tilting by moving the detected pixel to a reference location of the at least one pixel selected in the reference image.