KR100717861B1 - Method and apparatus for detecting motion using camera - Google Patents

Abstract

The present invention relates to a method for detecting a motion, and more particularly, to a method for detecting whether there is a motion of a person or an object between areas of an image by measuring a brightness change from image information acquired by a camera in a robot or the like. will be. The present invention includes the steps of acquiring an image from a camera at a predetermined cycle; Dividing the newly acquired image into unit pixels having a predetermined size by the camera and obtaining a change amount of brightness for each unit pixel by comparing with a previously obtained image; Dividing an image acquired by the camera into at least two areas, and obtaining a sum of the number of unit pixels whose variation in brightness exceeds a predetermined threshold value for each of the divided areas; Obtaining a difference between the sum of the number of unit pixels in two areas of the divided areas; And determining whether an object moves between the two areas according to a change in the difference between the sum of the number of unit pixels of the two areas.

Motion Detection, Brightness Change, Near Infrared LED

Description

Method and apparatus for detecting motion using camera image {Method and apparatus for detecting motion using camera}

1 is a flowchart illustrating a process of performing an embodiment of a motion detection method of the present invention.

Figure 2 shows an example in which the parameters measured in the course of the embodiment of the motion detection method of the present invention changes over time.

3 is a block diagram showing an embodiment of a motion detection apparatus of the present invention.

{Description of main parts of the drawing}

301: camera 302: infrared light emitting element

303: image information storage unit 304: brightness change extraction unit

305: Fill sector counter unit 306: Pixel number storage unit

307: pixel number comparison unit 308: motion discrimination unit

The present invention relates to a method for detecting a motion, and more particularly, to a method for detecting whether there is a motion of a person or an object between areas of an image by measuring a brightness change from image information acquired by a camera in a robot or the like. will be.

As a method of detecting a motion of a person or an object in a conventional surveillance system or the like, there are various methods of acquiring image information by an image device such as a camera and detecting motion from the image obtained thereby.

Where such a motion detection method is used, there are various monitoring or method systems with a camera or the like. In particular, with the recent development of related technologies, home robots with various forms and functions have appeared in addition to the limited-function industrial robots used in the conventional industrial sites, among which security robots perform security and security functions at home. In addition, the security robot uses the motion detection method as described above to perform the function of detecting the intrusion of outsiders and notifying the user.

However, conventional motion detection methods generally detect motion using an image acquired by a camera in an environment with sufficient lighting and in a daytime environment, and thus, accuracy and efficiency of motion detection are degraded in an environment where lighting is insufficient or at night. There is a problem. In particular, security robots and the like should detect the movement more accurately at night than daytime to determine the abnormality due to the nature of the function to perform.

Therefore, there is a need for a method and apparatus for accurately and efficiently detecting movement even in an environment where lighting or light is insufficient.

An object of the present invention is to provide a motion detection method and apparatus for accurately and efficiently detecting motion by using a change in brightness between areas on a camera image.

It is still another object of the present invention to provide a motion detection method and apparatus that can accurately detect motion even in an environment where lighting is insufficient by using an infrared light emitting device.

The motion detection method of the present invention comprises the steps of acquiring image information at predetermined intervals; Dividing newly acquired image information into unit pixels having a predetermined size and comparing the previously obtained image information with each other to obtain a change amount of brightness for each unit pixel; Dividing the obtained image information into at least two regions, and obtaining a sum of the number of unit pixels in which the amount of change in brightness exceeds a predetermined threshold value for each of the divided regions; Obtaining a difference between the sum of the number of unit pixels in two areas of the divided areas; And determining whether an object moves between the two areas according to a change in the difference between the sum of the number of unit pixels of the two areas.

In the present invention, the step of acquiring the image information at a predetermined period is preferably to obtain the image information by using a camera, more preferably the step of emitting infrared rays forward from the infrared light emitting element attached to the camera; And acquiring a front image from the camera. In addition, the infrared light emitting device is more preferably a near infrared LED.

In the present invention, the step of dividing the obtained image information into at least two areas and obtaining the sum of the number of unit pixels whose brightness variation exceeds a predetermined threshold value for each divided area is determined by the left and right sides of the acquired image information. Or it is preferable to divide into one selected from left and right and up and down.

In the present invention, the step of obtaining the difference between the sum of the number of unit pixels of two areas among the divided areas is preferably to obtain the difference between the sum of the number of unit pixels of two areas adjacent to each other, and the number of unit pixels of the two areas. The determining of whether or not the object moves between the two areas according to the change of the difference between the sums may be performed by comparing the difference between the sum of the number of unit pixels in the two adjacent areas with a predetermined reference value. Do.

The motion detection apparatus of the present invention includes an image information storage unit for storing image information input at a predetermined cycle; A brightness change extractor for dividing newly input image information into unit pixel units having a predetermined size and comparing the previously input image information stored in the image information storage unit to obtain a change amount of brightness which is a change amount of brightness for each unit pixel; A pixel number counter unit for dividing an image acquired by the camera into at least two areas to obtain a sum of the number of unit pixels whose brightness variation exceeds a predetermined threshold value for each of the divided areas; A pixel number comparison unit for obtaining a difference between the sum of the number of unit pixels in two areas of the divided areas; And a motion discrimination unit determining whether an object moves between the two areas according to a change in the difference between the sum of the number of unit pixels of the two areas.

In the present invention, the motion detection device preferably further comprises a camera for acquiring the image information, it is more preferable that the infrared light emitting element for emitting light in the direction of acquiring the image is attached to the camera, the infrared light emitting It is also preferred that the device is a near infrared LED.

In the present invention, the pixel number counter divides the obtained image information into one selected from left, right, up, down, left and right, and top and bottom to calculate the sum of the number of unit pixels whose brightness variation exceeds a predetermined threshold for each divided area. It is preferable.

Preferably, the pixel number comparison unit obtains a difference between the sum of the number of unit pixels in two adjacent areas, and the motion discriminator determines the difference between the sum of the number of unit pixels in the two adjacent areas with a predetermined reference value. It is more preferable to determine whether there is motion in comparison.

The motion detection apparatus of the present invention preferably further includes a pixel number storage unit that stores a change in the sum of the number of unit pixels for each region obtained by the pixel number counter unit.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In adding reference numerals to components of the following drawings, it is determined that the same components have the same reference numerals as much as possible even if displayed on different drawings, and it is determined that they may unnecessarily obscure the subject matter of the present invention. Detailed descriptions of well-known functions and configurations will be omitted.

The motion detection method of the present invention detects motion by analyzing brightness information from an image acquired by an image acquisition means such as a camera provided in a robot. More specifically, the image acquisition means such as a camera acquires an image for a certain shooting range, such as a fixed posture. By continuously performing the image acquisition and the motion detection process according to a predetermined period, it is possible to determine whether there is motion by grasping the state of the brightness change on the image according to the change of time.

1 is a flowchart illustrating a process of performing an embodiment of the present invention.

In the embodiment shown in FIG. 1, the motion detection method emits infrared rays forward from the infrared light emitting element attached to the camera (S101), acquires an image of the front from the camera (S102), and acquires the newly acquired image from the camera. The amount of change in brightness is calculated for each unit pixel by dividing the image into a unit pixel having a predetermined size (S103), and dividing the image obtained by the camera into at least two or more regions. The sum of the number of unit pixels for which the amount of change in brightness exceeds a predetermined threshold value (hereinafter referred to as 'brightness change pixel number') is obtained (S104), and the difference between the number of brightness change pixels in two areas among the divided areas is obtained (S105). ), Comparing the difference in the number of brightness change pixels between the regions with a predetermined reference value (S106), and determining whether there is movement between the two regions (S107). It is a row.

The embodiment illustrates a process of acquiring a single image and detecting a motion in the motion detection method of the present invention, which continuously acquires an image at a predetermined period and continuously detects motion. All steps of the above embodiment or steps after step S102 may be repeatedly performed to continuously detect motion.

In the above embodiment, the infrared light emitting device attached to the camera before the operation (S102) of acquiring an image from the camera emits infrared rays in a direction in which the camera acquires the image (S101). When the light emitted from the infrared light emitting device is irradiated to an object such as a person or an object, the camera may acquire an image in the form of a black and white image according to the intensity of the infrared light.

The camera may be used in any kind and form as long as it can acquire image information, particularly brightness information of the image.

Preferably, the infrared light emitting device attached to the camera is a near infrared LED, and a person may not recognize the light emitted by the light emitting device, and the camera may recognize the image by the emitted light.

The obtained image is divided into unit pixels having a predetermined size, and the amount of change in brightness for each unit pixel is obtained by comparing with the image just before (S103). The change in brightness is a change in brightness of the previous frame of the image of the current frame, and the brightness of each unit pixel for each frame is determined by the amount of light received at the corresponding unit pixel in the image acquired by the camera. Expressed as a proportional figure.

의 위치를 갖는 특정의 단위픽셀에 대해서 이전 프레임의 영상에서의 밝기값은

로, 현재 프레임의 영상에서의 밝기값은

로 각각 표현되며, 이전프레임에 대한 현재프레임의 밝기의 변화량은

로 표현된다.On video

For a particular unit pixel with the position of, the brightness value in the image of the previous frame is

The brightness value in the image of the current frame is

Represented by, and the change of brightness of the current frame with respect to the previous frame is

It is expressed as

Subsequently, the obtained image is divided into two or more regions, and the sum of the number of unit pixels in which the amount of change in brightness exceeds a predetermined threshold value is obtained for each of the divided regions (S104).

The image is divided into a predetermined number of regions, and the shape of the division may be any, but it is preferable that the image is divided into two regions divided into left and right or up and down or divided into four regions divided into left and right and up and down. In addition, by adjusting the size of each area divided as necessary, the image by the camera may be divided into a larger number of areas.

Each of the divided areas includes a plurality of unit pixels, and for each of the unit pixels, it is determined whether the amount of change in brightness obtained in step S103 exceeds a predetermined threshold, and the amount of change in brightness for each of the divided areas. The sum of the number of unit pixels exceeding the threshold is found, which is the number of brightness change pixels.

이라는 특정 영역에 대해서 상기 밝기변화 픽셀수를 세는 카운터를

, 상기 임계값을

이라 할 때,

는 다음에 의해 구할 수 있다.

A counter that counts the brightness change pixels for a specific area

, The threshold

When I say

Can be obtained by

, if

, if

The number of brightness change pixels for the specific region can be seen as representing the degree of movement in the specific region, and is stored in the storage means as it changes over time.

Subsequently, two regions of the divided regions of the image are selected to obtain a difference in the number of brightness change pixels between the selected regions (S105), and the difference in the number of brightness change pixels is compared with a predetermined reference value (S106). In step S107, it is determined whether there is a movement between the selected regions.

An example in which the difference between the number of brightness change pixels and the number of brightness change pixels for each region changes with time is shown in FIG. 2.

이라는 영역의 밝기변화 픽셀수

의 시간에 대한 변화(201),

이라는 영역의 밝기변화 픽셀수

의 시간에 대한 변화(202) 및 상기 두 영역의 밝기변화 픽셀수 사이의 차

의 시간에 대한 변화(203)의 일 예를 나타낸 것이다. The three graphs of Figure 2 are each in order from top to bottom

The number of pixels of brightness change in the area

Change over time of 201,

The number of pixels of brightness change in the area

The difference between the change 202 over time and the number of brightness change pixels in the two regions

An example of the change 203 with respect to time is shown.

영역에서 움직임의 정도가 크다가(201) 나중에는

영역에서 움직임의 정도가 커지며(202),

영역으로부터

영역으로 사람 또는 사물의 움직임이 있었음을 알 수 있다. The number of brightness change pixels for the specific region may be regarded as representing the degree of movement in the specific region. If you refer to the graph above,

The degree of movement in the area is large (201)

The degree of movement in the region increases (202),

From the realm

It can be seen that there was a movement of a person or an object in the area.

영역과

영역의 밝기변화 픽셀수를 비교함으로써 이루어지며, 특히 상기

의 값을 기준값과 비교하여 움직임 여부를 판정할 수 있다. The determination of the movement between the regions is

Area and

By comparing the number of pixels of the brightness change of the area,

The value of can be compared with the reference value to determine whether or not the motion.

의 값이 상기 기준값보다 커지거나 작아지는 순간에 영역 간 움직임이 있는 것으로 판정할 수 있다. 상기 실시예에서는 기준값을 양과 음의 문턱값(±Th_diff)으로 두었으며,

값이 양의 문턱값(+Th_diff)보다 커지는 경우에는

로부터

로의 움직임이 있는 것으로,

값이 음의 문턱값(-Th_diff)보다 작아지는 경우에는

로부터

로의 움직임이 있는 것으로 각각 판정한다. 또는 상기 기준값을 0으로 두는 경우에는

값의 부호가 바뀌는 경우에 영역 간 움직임이 있는 것으로 판정할 수 도 있다. The reference value may be 0 or a predetermined threshold value (± Th_diff) as shown in graph 203, and

It may be determined that there is an inter-regional movement at a moment when the value of becomes larger or smaller than the reference value. In the above example, the reference value is set as a positive and negative threshold value (± Th_diff),

If the value is greater than the positive threshold (+ Th_diff)

from

In the movement of the furnace,

If the value is less than the negative threshold (-Th_diff)

from

It is judged that there is movement of furnace. Or when the reference value is set to 0

It can also be determined that there is movement between regions when the sign of the value changes.

Figure 3 shows an embodiment of a motion detection device of the present invention.

In the embodiment of FIG. 3, the motion detection apparatus includes a camera 301 for acquiring image information at a predetermined cycle, an infrared light emitting element 302 attached to the camera, and an image information storage unit for storing image information acquired from the camera ( 303) and dividing the newly acquired image from the camera 301 into unit pixels of a predetermined size, and comparing the image previously acquired and stored in the storage means 303 to obtain a change amount of brightness for each unit pixel. The extraction unit 304 divides the image acquired by the camera into at least two areas, and adds the number of unit pixels for which the amount of change in brightness exceeds a predetermined threshold value for each of the divided areas (hereinafter referred to as 'number of brightness change pixels'). The pixel number counter 305 for calculating the difference, the pixel number storage unit 306 for storing the brightness change pixel number, and the pick for calculating the difference between the brightness change pixels of two areas of the divided areas. Comparison unit 307 and a motion determination section 308 to determine whether there is motion between the brightness changes in the order of pixels of the two regions compared with a predetermined reference value between the regions.

Each part of the embodiment of FIG. 3 performs each step of the embodiment of FIG. 1, the infrared light emitting element 302 performs step S101 of the embodiment of FIG. 1, and the camera 301 performs step S102, The brightness change extracting unit 304 performs step S103, the pixel number counter unit 305 performs step S104, the pixel number comparing unit 307 performs step S105, and the motion discrimination unit 308 performs step S103. S106 and step S107 are performed respectively. The configuration and operation of the respective parts are not significantly different from those mentioned with respect to the embodiment of FIG. 1, and thus detailed description thereof will be omitted.

In the above embodiment, the image information storage unit 303 stores image information obtained by the camera 301. Image information is periodically acquired by the camera 301, and an image of a previous frame is stored in the image information storage unit 303. The brightness change extractor 304 compares the image of the previous frame stored in the image information storage unit 303 with the image of the current frame acquired by the camera 301 to obtain a change amount of brightness, and the image of the current frame is again The image information is stored in the storage unit 303 and compared with the image of the next frame.

In the above embodiment, the pixel number storage unit 306 stores the number of brightness change pixels acquired by the pixel number counter unit 305. The pixel number comparison unit 307 obtains the difference in the number of brightness change pixels between the areas, and the motion discrimination unit 308 determines whether there is motion using the difference in the number of brightness change pixels between the areas. It is also possible to determine whether there is motion by using a change in the brightness difference between the pixels.

In this embodiment, for this purpose, the number of brightness change pixels for each area of the previous frame stored in the pixel number storage unit 306 is compared with the number of brightness change pixels of the current frame acquired by the pixel number counter unit 305. The number of brightness change pixels for each area is stored in the pixel number storage unit 306 again.

In order to determine whether to move by using the change in the difference in the number of brightness change pixels, the number of brightness change pixels for each region is stored in the pixel number storage unit 306 in the previous frame. Alternatively, the difference in the number of brightness change pixels between specific regions may be stored in the storage means. In this case, the difference in the number of brightness change pixels obtained by the pixel number comparison unit 307 is stored in the storage means.

In the method and apparatus of the present invention, it is particularly preferable to use a near infrared LED as the infrared light emitting element attached to the camera. This is because the infrared light emitted from the near-infrared LEDs causes diffuse reflection in the retina when passing through the pupil of a human or animal, causing the pupil to appear bright on the camera screen. When a person or an animal moves, the number of pixels whose brightness changes beyond a threshold value changes due to the position of the pupil on the screen, and the movement between the divided areas of the screen of the person or animal is easily performed according to the change in the number of brightness change pixels. Can be detected.

As described above, it has been described with reference to the preferred embodiment of the present invention, but those skilled in the art various modifications and changes of the present invention without departing from the spirit and scope of the present invention described in the claims below I can understand that you can.

As described above, according to the method and apparatus of the present invention, the motion can be detected accurately and efficiently by utilizing the change in brightness of each image area.

In addition, according to the method and apparatus of the present invention, by using the near-infrared LED, it is possible to accurately and efficiently detect the movement of a human or an animal even in an environment where lighting is insufficient.

Claims (15)

Acquiring image information at predetermined intervals; Dividing newly acquired image information into unit pixels having a predetermined size and comparing the previously obtained image information with each other to obtain a change amount of brightness for each unit pixel; Dividing the obtained image information into at least two regions, and obtaining a sum of the number of unit pixels in which the amount of change in brightness exceeds a predetermined threshold value for each of the divided regions; Obtaining a difference between the sum of the number of unit pixels for two areas of the divided areas; And And determining whether an object moves between the two areas according to a change in the difference between the sum of the number of unit pixels of the two areas. The method of claim 1, wherein the obtaining of the image information at the predetermined period A motion detection method comprising acquiring image information using a camera. The method of claim 2, wherein the obtaining of the image information at the predetermined period Emitting infrared rays forward from the infrared light emitting element attached to the camera; And acquiring a front image from the camera. 4. The method of claim 3, wherein the infrared light emitting element is a near infrared LED. The method of claim 1, wherein dividing the acquired image information into at least two regions and obtaining a sum of the number of unit pixels whose brightness variation exceeds a predetermined threshold for each divided region determines the acquired image information. Motion detection method characterized in that divided into one selected from up, down or left and right and up and down. The method of claim 1, wherein the obtaining of the difference between the sum of the number of unit pixels of the two regions of the divided regions is to obtain the difference between the sum of the number of unit pixels of two adjacent regions. The method of claim 6, wherein determining whether the object moves between the two areas according to a change in the difference between the sum of the number of unit pixels in the two areas comprises determining a difference between the sum of the number of unit pixels in the two adjacent areas. The motion detection method of claim 1, characterized by determining whether or not the motion compared to the reference value. An image information storage unit which stores image information input at predetermined intervals; A brightness change extracting unit for dividing newly input image information into unit pixels having a predetermined size and comparing the previously input image information stored in the image information storage unit to obtain a change amount of brightness for each unit pixel; A pixel number counter unit for dividing an image acquired by the camera into at least two areas to obtain a sum of the number of unit pixels whose brightness variation exceeds a predetermined threshold value for each of the divided areas; A pixel number comparison unit for obtaining a difference between the sum of the number of unit pixels in two areas of the divided areas; And And a motion discrimination unit configured to determine whether an object moves between the two areas according to a change in the difference between the sum of the number of unit pixels of the two areas. The apparatus of claim 8, further comprising a camera that acquires image information. 10. The apparatus of claim 9, wherein the camera is equipped with an infrared light emitting element that emits light in a direction of acquiring an image. The apparatus of claim 10, wherein the infrared light emitting element is a near infrared LED. The method of claim 8, wherein the pixel number counter unit divides the obtained image information into one selected from left, right, up, down, left and right, and top and bottom to determine the number of unit pixels for which the amount of change in brightness exceeds a predetermined threshold for each divided area. Motion detection device, characterized in that the sum is obtained. The apparatus of claim 8, wherein the pixel number comparison unit obtains a difference between the sum of the number of unit pixels in two adjacent areas. The motion detection apparatus of claim 13, wherein the motion determination unit determines whether to move by comparing a difference between the sum of the number of unit pixels of two adjacent areas with a predetermined reference value. The motion detection apparatus of claim 8, further comprising a pixel number storage unit configured to store a change in the sum of the number of unit pixels for each region obtained by the pixel count counter.

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