KR20040106783A - Surveillance camera apparatus and operating method of the same - Google Patents

Abstract

PURPOSE: A monitoring camera and a method for operating the camera are provided to minimize the quantity of images to be stored by intermittently capturing images and remarkably reduce storage memory capacity by storing only necessary images. CONSTITUTION: A monitoring camera includes a controller(10), a sensor(14), an image capturing unit(11), a comparator(12), and a memory manager(13). The controller controls the components of the camera. The sensor senses an object(100) and transmits the sensed signal to the controller. The image capturing unit intermittently captures images of the object multiple times to generate a plurality of frame images. The comparator compares the plurality of frame images to a reference frame image to set storage priority. The memory manager stores the frame images in a memory(15) according to the storage priority.

Description

Surveillance camera apparatus and operating method of the same}

The present invention relates to a surveillance camera device and a method of operating the same, and more particularly, a surveillance camera device and an operation thereof, which can reduce the use capacity of a memory by selectively storing only a frame image containing necessary information among a plurality of captured frame images. It is about a method.

In general, surveillance cameras are installed in areas where people or animals are prohibited from accessing, or areas that need to be monitored, and may be installed in, for example, restricted areas, warehouses, parking lots, or buildings. Recently, a surveillance apparatus of capturing a region limited by a CCTV camera as a video and recording and storing the same in a digital storage device (DVR) has been widely used. However, such equipment is not only expensive but also continuously photographs for 24 hours regardless of the appearance of humans or animals, so a large amount of digital images to be recorded must be provided to provide a large storage device. This difficulty requires high image compression technology along with the expansion of storage memory. In addition, even when searching the recorded image afterwards, it is often necessary to look back the entire stored image in order to find the necessary screen. In this case, since a large amount of images are stored that are not related to the appearance of humans or animals, it is difficult to find the necessary screen.

The present invention has been made to solve the above problems, an object of the present invention is to provide a surveillance camera device to operate the camera in accordance with the appearance of people or animals.

In addition, another object of the present invention is to provide a surveillance camera device in which the capacity of an image to be recorded and stored is minimized by intermittently capturing screens at predetermined intervals instead of capturing screens continuously when a person or an animal appears in a set area. To provide.

In addition, it is another object of the present invention to provide a surveillance camera device that can significantly reduce the storage memory capacity by comparing the captured image and to store only the necessary image according to the storage order.

The invention also aims to provide a method of operating such a surveillance camera.

According to the present invention, not only does not need to build a large memory to store the necessary image, but also a high level of difficulty such as an image compression technique is not required.

1 is a front view showing a schematic appearance of a surveillance camera device according to a preferred embodiment of the present invention.

2 is a schematic block diagram showing the configuration of a surveillance camera apparatus according to a preferred embodiment of the present invention.

3 is a view schematically showing the angle of view and the sensor angle of the surveillance camera device according to an embodiment of the present invention.

4 is a flowchart illustrating a method of operating a surveillance camera apparatus according to a preferred embodiment of the present invention.

5 is a diagram illustrating an example of frame images photographed intermittently a plurality of times by the surveillance camera device according to an exemplary embodiment of the present invention.

6 is a signal diagram schematically illustrating a camera photographing signal and a lamp lighting signal in a surveillance camera device according to an exemplary embodiment of the present invention.

7 is a flowchart illustrating a method of operating a surveillance camera device according to another embodiment of the present invention.

FIG. 8 is a diagram schematically showing an example of deleting subframe images among frame images recorded first in a memory and storing frame images photographed second in accordance with the present invention.

9 is a flowchart illustrating a method of operating a surveillance camera device according to another embodiment of the present invention.

FIG. 10 is a diagram for describing a method of storing photographed frame images in a memory, according to another exemplary embodiment.

Surveillance camera apparatus according to the present invention for achieving the above object, the control unit for controlling each unit; A detection sensor for detecting a subject and transmitting the detection signal to the controller; A photographing unit which generates a plurality of digitized frame images by intermittently photographing an area in which the subject is present a plurality of times as a photographing signal is input from the controller; A comparison unit configured to set a storage order by comparing the photographed plurality of frame images with a reference frame image; And a memory manager configured to store the frame images in a memory according to the storage order.

Preferably, the comparison unit sets the frame image having the largest amount of image change to be a higher frame image.

More preferably, the comparator divides the frame image to be photographed into a plurality of regions and sets the frame image having the largest amount of image change in at least one specific region among them to be an upper frame image.

According to the invention, the detection sensor is installed to cover the angle of view of the photographing unit.

In addition, the detection sensor is preferably provided as a pair on both sides of the camera lens of the photographing unit.

Preferably, the memory manager stores the frame image in the memory as much as the number of valid frames.

Also, preferably, the memory manager deletes the remaining lower frame images except the upper frame images corresponding to the effective number of frames among the frame images previously recorded in the memory, and stores the frame images subsequently photographed in the storage area.

According to another aspect of the invention, (a) detecting the subject; (b) generating a plurality of digitized frame images by intermittently photographing an area in which the subject is present a plurality of times according to the detection of the subject; (c) setting a reference frame image; (d) calculating an amount of image change by comparing the reference frame image and the plurality of frame images, respectively; (e) determining a storage order of the frame images according to the amount of image change; And (f) storing the frame images in accordance with the determined storage order.

Here, the reference frame image is preferably set to a frame image in which the subject is detected by the detection sensor but is not photographed.

More preferably, the reference frame image is set as the first frame image among the frame images photographed intermittently a plurality of times.

Preferably, in step (d), the change amount of the image is obtained by calculating the change amount for each pixel.

Preferably, when the storage order is the same in step (e), the image having the large amount of change in the center is set as the upper frame image.

Preferably, in step (f), the upper frame images corresponding to the preset valid frame number are stored.

More preferably, in the step (f), the remaining lower frame images except the upper frame images corresponding to the effective number of frames among the stored frame images are deleted, and the second captured frame images are stored.

According to another aspect of the invention, (a) detecting the subject; (b) generating a plurality of digitized frame images by intermittently photographing an area in which the subject is present a plurality of times according to the detection of the subject; (c) setting a reference frame image; (d) calculating an amount of image change by comparing the reference frame image and the plurality of frame images, respectively; (e) determining valid frame images according to the image variation amount; And (f) determining whether the storage capacity of the memory is exceeded, and if not, storing the photographed plurality of frame images; And (g) if in step (f) the storage capacity of the memory is exceeded, it is determined from the initial storage area of the memory whether the previously stored frame image is a valid frame image, and if it is not a valid frame image, it is deleted and subsequent frames There is provided a method for operating a surveillance camera, including storing an image.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 shows a schematic appearance of a surveillance camera device according to a preferred embodiment of the present invention in a front view. Referring to the drawings, the surveillance camera device of the present invention includes a main body case 1 and a camera lens 2 installed on the front of the main body case 1 for capturing an image.

A plurality of lamps 3 are provided around the camera lens 2 to illuminate the space where the subject is located by being momentarily lit when the image is taken. In addition, one side of the camera lens 2 is provided with a sensor 14a, 14b for detecting the appearance of a subject, such as a person or animal, preferably, the sensor 14a, 14b are both sides of the camera body Are provided in pairs. More preferably, the detection sensors 14a and 14b are installed to cover an area larger than the angle of view Θ _{c of the} camera, as shown in FIG. 3.

2 shows a specific configuration of the surveillance camera device of the present invention. Referring to the drawings, the surveillance camera device of the present invention is controlled by the control unit 10 for controlling each part of the device, and when a subject such as a person or an animal appears from the control unit 10 to intermittently receive a plurality of frames of the image of the subject. A photographing unit 11 for photographing, a comparison unit 12 which calculates a pixel change amount by comparing the photographed frame images with each other, and determines a storage order of the frame images therefrom, and a memory according to the control of the controller 10; And a memory management unit 13 storing the captured frame image and managing the same.

In addition, the surveillance camera device includes a detection sensor 14 that detects the appearance of the subject 100, outputs it as an electric signal, and transmits it to the controller 10.

The photographing unit 11 is a part for capturing an actual image, including an optical structure such as a camera lens 2, and a charged coupled device for converting a photographed image into a digital signal. Has a structure. According to the present invention, the photographing unit 11 is controlled by the controller 10 to generate a plurality of frame images by intermittently photographing a plurality of times when a subject appears.

The comparison unit 12 compares the plurality of frame images photographed by the photographing unit 11 with the reference frame image to calculate a value for each image change amount. As will be described later, the plurality of frame images photographed have a storage rank determined according to the calculated image change amount.

The memory manager 13 stores the photographed frame images in the memory 15 in order from the upper frame images according to their storage order. In this case, if there is a set valid frame number, the upper frame images are first stored in the memory 15 corresponding to the set valid frame number, and the remaining lower frame images except for these are not stored. Alternatively, once the lower frame images are stored in the memory 15, they may be deleted from the lower frame as needed and another upper frame image may be recorded in the deleted storage area. Preferably, a flash memory is employed as the memory 15. In the present invention, the memory management unit 13 is described as simply storing the frame image without additional processing. However, in order to further increase the effect of the present invention, the image compression function may be simultaneously implemented.

As described above, the detection sensor 14 includes a pair of sensors 14a and 14b respectively installed on both sides of the camera lens 2, and preferably PIR (Pyroeiectric) capable of detecting an animal's fine movement. infrared ray sensor is adopted. In the present invention, various sensors including a PIR sensor may be employed, and since the operation principle of these sensors is well known, the detailed description thereof will be omitted.

An embodiment of the installation of the sensor 14 is shown in detail in FIG. 3. Referring to FIG. 3, the camera lens 2 of the photographing unit 11 has an angle of view Θ _c , which is an angle at which an image can be taken to the maximum, and thus an effective photographing area covered by the angle of view Θ _c ( Only the subject present in A _eff ) is photographed by the camera.

Preferably, the detection sensors 14a and 14b have a detection angle Θ _s that can detect when the subject 100 appears, and preferably includes an effective shooting area A _{eff of the} camera. It is installed to cover a large area. As shown in the drawing, even if the subject 100 is detected by the detection sensors 14a and 14b, the non-shooting region A _sen where the subject 100 cannot be photographed because the effective photographing region A _eff is removed. (Indicated by hatching) is formed. However, the installation of such a sensor is not limited by the present embodiment and may be implemented in various modifications to achieve a function of photographing according to the detection of the subject.

According to the present invention, when the subject 100 is photographed by the camera in a dark situation, the lighting unit 16 is provided to provide illumination in an instant. The lighting unit 16 turns on the lamp 3 by applying power to the lamp 3 instantaneously from a power not shown according to a signal from the controller 10.

Then, the operation of the surveillance camera device according to the present invention configured as described above will be described with reference to FIG.

Surveillance camera apparatus according to the present invention is installed in a place where the entrance or restriction of people or animals, such as a garage of a parking lot or a store, or to monitor their movement. Assuming that the subject 100 passes in the same direction as the arrow D of FIG. 3 in this state, the non-shooting region is a region where the subject 100 is detected by the detection sensor 14a but cannot be photographed. When entering (A _sen ), the detection sensor 14a detects the subject 100 and transmits the detection signal to the controller 10. The controller 10 continuously determines whether a detection signal is input (step S200). If the object detection signal is transmitted from the detection sensor 14, the controller 10 determines that the object 100 has appeared within the restricted area, and photographs the camera. In order to output the shooting signal to the photographing unit 11 (step S210). In addition, in operation S210, a lamp lighting signal may be output to the lighting unit 16 to light up the lamp 3 to selectively photograph the subject 100 more clearly.

Next, the photographing unit 11 receiving the photographing signal photographs an area in which a subject is intermittently at predetermined intervals to generate a plurality of frame images (step S220). In the present specification and claims, the term 'intermittently photographing an image multiple times' is used to mean photographing an image several times, for example, six times every predetermined time interval, for example, 1/10 second. In this embodiment, an example in which six frame images I _R to I ₅ are generated by intermittently photographing six times for the case where the subject 100 is moved in the direction of the arrow D of FIG. 3 is illustrated in FIG. 5. Indicated. In this case, the lighting unit 16 may also illuminate the photographing area by lighting the lamp 3 installed in the main body case 1 according to the lighting signal (step S230). Preferably, the photographing signal and the lamp lighting signal may be applied as shown in FIG. 6. As can be seen from the drawing, the application of the lamp lighting signal is performed immediately before the application of each frame shooting signal.

When generation of the frame images is completed according to the shooting, a reference frame image is set (step S240). The reference frame image refers to an image obtained by photographing a normal state or a state closest to the subject 100 before appearance. For example, the reference frame image may be pre-stored in the memory 15 by photographing a state in which the subject 100 does not appear at a predetermined cycle. Preferably, according to the present embodiment illustrated in FIG. 5, the reference frame image I _R is the first frame image captured by the photographing unit 11 at the moment when the sensing sensor 14a detects the subject 100. Becomes In this case, the subject 100 is present in the non-photographing area A _sen and is detected by the detection sensor 14a, but is not photographed because it is outside the effective photographing area A _eff . Therefore, the subject 100 will not be found in the captured frame image at this time. This reference frame image I _R is not limited by this embodiment and may be set in various ways. For example, the first frame image photographed in step S220 may be set as the reference frame image. Alternatively, the camera may periodically take an image to set the most recent image as the reference frame image before the event occurs.

Once the reference frame image I _R is set, the comparator 12 compares the reference frame image I _R with the remaining frame images I ₁ to I ₅ in order based on such data. The amount of image change is calculated for each frame image (step S250). The frame images are digitized bitmap series images, and the amount of change of the image can be grasped by comparing the reference frame image I _R with the pixels of each frame image I ₁ to I ₅ . Since a technique for identifying an image change difference by pixel comparison is already known, a detailed description thereof will be omitted.

Referring to the example illustrated in FIG. 5, when the reference frame image I _R and the frame images I ₁ to I ₅ are compared with each other, the second frame image I ₂ and the third frame image I ₃ are compared. The amount of change in the pixels of the?) Is larger than the amount of change in the pixels of the first, fourth, and fifth frame images I ₁ (I ₄ ) (I ₅ ).

Subsequently, the controller 10 determines the storage order of each frame image according to the frame image change amount result of the comparator 12 (step S260). The storage order is proportional to the amount of change in the image, and accordingly, the frame image having the largest amount of change in the image is set as the first priority in comparison with the reference frame image I _R. For example, according to the embodiment shown in FIG. 5, the second frame image I ₂ or the third frame image I ₃ (I ₅ ) with the largest amount of pixel variation will be the highest frame image.

In step S270, the controller 10 determines whether there is a same rank among the ranks of the frame images. The case of the same rank is a case where the amount of change of pixels with respect to the reference frame image I _R is the same, for example, when the second frame image I ₂ and the third frame image I ₃ are such.

If there are frame images with the same rank, the sequence proceeds to step S280 where the frame image with the greatest amount of change in the center of the screen among those frame images is set higher. This is to set the frame image captured at the moment when the subject 100 such as a person or an animal is located at the center of the screen as the upper storage order. In detail, as illustrated by a dotted line in FIG. 5, the frame image may be partitioned into a plurality of virtual regions, and the difference in pixels may be determined for each region by comparing the amount of pixel change in each of the sections in step S250. Therefore, the frame image showing the greatest change in the most central region becomes the third frame image I _{3 in} which the subject 100 is located at the center, and thus is set as a higher frame image than the second frame image I ₂ . do.

In the present invention, the storage rank is not limited by the embodiment and various methods may be applied. For example, the user may divide the image frame into a plurality of partitions as shown in FIG. 5 in advance (parts 1 to 9 in the drawing) and select a frame image having the highest rate of change for any particular partition. It can also be set as an upper frame image. Which section to base on may be selectively set by the user.

As another alternative, it is also possible to store all frame images whose variation exceeds a certain reference value as compared to the reference frame image. At this time, how many frame images to store may be appropriately set according to a user's selection.

When the storage order of each of the frame images (I ₁ ) to (I ₅ ) is determined, the control unit 10 transmits it to the memory management unit 13 to store the frame image according to the set storage order (step S290). In this case, the frame images I ₁ to I ₅ are stored in the memory 15 as many as the number of valid frames.

According to the present invention, the number of valid frames is set to save the storage space of the memory. The number of valid frames means a number of frames that are set by a user and must be stored permanently without being deleted. For example, in the embodiment of FIG. 5, when the user sets the number of valid frames to 2, the second frame image I ₂ and the third frame image I ₃ are determined to be valid frames, and other remaining frames. The images I ₁ , I ₄ , and I ₅ are images that may be deleted because they are not included in the valid frame. The effective number of frames can be appropriately selected according to the user's convenience and is smaller than the number of frames taken by the camera.

In the present embodiment, when the number of valid frames is set to 2, only the third frame image I ₃ and the second frame image I ₂ are stored by the memory management unit 13 from the top to the second storage order. 15 and the remaining first, fourth and fifth frame images I ₁ (I ₄ ) (I ₅ ) are not stored. Therefore, even if a plurality of frame images are taken, only the effective frame number of image data is stored in the memory according to the storage order. This can prevent waste of storage space in the memory by storing unnecessary image data.

A method of operating a surveillance camera according to another embodiment of the present invention is shown in FIG. 7. In the flowchart of the drawing, the steps indicated by the same reference numerals as those shown in FIG. 4 represent the same steps, and thus, repeated description thereof will be omitted.

According to the present embodiment, the frame images I ₁ to I _{5 in which the} storage order is determined are stored in the storage space of the memory 15 in order from the upper frame image to the lower frame image, as shown schematically in FIG. 8. In the drawing, five frame images 1st_1, 1st_2, 1st_3, 1st_4 and 1st_5 photographed when the first event occurs are sequentially recorded and stored in the storage space of the memory according to the storage order.

Subsequently, five frame images 2nd_1, 2nd_2, 2nd_3, 2nd_4 and 2nd_5 captured by the surveillance camera by another second event occur from some storage spaces in which the frame images of the first event are stored according to the storage order. It is stored (step S300). Specifically, when the number of valid frames is 2, in storing the frame images 2nd_1 to 2nd_5 for the second event, as shown in FIG. 8, the memory manager 13 stores the first frame already stored in the memory 15. Among the images 1st_1 to 1st_5, the remaining frame images 1st_3, 1st_4 and 1st_5 except for the highest frame image 1st_1 to the second frame image 1st_2 are stored from the storage space where the second frame image 2nd_1 to (2nd_5) are stored in order according to their storage order. In other words, subsequent frame images are overlaid and stored in the frame image storage area of the preceding frame images except for valid frame images. Therefore, the storage space of the memory 15 deletes previously recorded frame images other than the effective frame number every time a plurality of event shots are taken, and stores new frame images in this order.

An example of a method of operating a surveillance camera according to another embodiment of the present invention is shown in FIG. 9. In the drawings, the same reference numerals as used in the previous drawings indicate the same steps.

In operation S400, the memory manager 13 under the control of the controller 10 determines whether the storage space of the memory 15 is used up to exceed the capacity before storing the frame image. If it is determined in the above step that the storage capacity of the memory 15 is not exceeded, the flow proceeds to step S410 to store the frame images in order. In this case, the stored frame image may be according to the storage order or may be in the shooting order. However, the ranking of each frame image will be recorded and stored together. More preferably, the frame image is divided into a valid frame image to be permanently stored and a frame image which may be deleted compared to the reference frame image, and stored in the memory together with such information.

In step S420 after storing the frame image, it is determined whether all the captured frame images are stored. If not, the method returns to step S400 to check whether the memory capacity is exceeded, and then stores the next frame image. By repeatedly performing this process, all the captured frame images can be stored.

In step S400, if it is determined that the capacity of the memory 12 is exceeded, the flow proceeds to step S430. In step S430, the lower frame images other than the valid frame images of the frame images already recorded and stored in the memory 12 are sequentially deleted from the beginning of the memory storage area, and the frame images subsequently photographed in the storage area are sequentially arranged. Save it.

To describe this in more detail, referring to FIG. 10, it can be seen that frame images 1st_1 to Nth_5 photographed in the storage area of the memory are sequentially stored. For convenience, the frame image was taken N times for N event occurrences and 5 frame images were taken for each shot. In this case, when the Nth frame images Nth_1 to Nth_5 are stored, the storage capacity of the memory 12 is exhausted. The frame images of this embodiment are stored in order of shooting order rather than storage order. When the (N + 1) th frame images (N + 1) th_1 to (N + 1) th_5 are captured by the surveillance camera of the present invention, it is determined that the storage capacity of the memory has been exceeded, and the first storage area R is determined. Returning, it is determined whether the frame image 1st_1 stored in the area is a valid frame image. Such determination is possible by the data recorded in step S410. If the first frame image 1st_1 should not be deleted, it is next determined whether the second frame image 1st_2 is a valid frame image. As a result, if the second frame image 1st_2 is deleted, the memory manager 13 deletes the frame image 1st_2 and the (N + 1) th frame images (N + 1) th_1 to (N + 1). save th_5 by overwriting it in that area. By repeatedly performing such a method, subsequent frame images are sequentially stored in the frame image storage area which may be deleted. In addition, by repeating this process for the first time again and again, it is possible to eventually fill all the storage areas of the memory 15 with the valid frame image.

According to the present invention, instead of capturing images continuously for 24 hours, the frame images are captured intermittently a plurality of times at the time of event occurrence, compared with the reference frame images, and selected from the frame images with the largest amount of image change, and the required values are stored. Since the remaining frame images are not stored or are subsequently deleted, not only can significantly reduce the storage space of the memory, but also does not require a difficult image compression technique for storing images as in the prior art. These will significantly reduce the manufacturing and operating costs of surveillance camera devices. More preferably, although the embodiment of the present invention does not describe the image compression technology, such a technology is not excluded from the present invention, and the effect of the present invention may be further doubled if an image compression technology such as MPEG or MJPEG is added. . Furthermore, according to the present invention, since the frame images stored in the memory are higher frame images in the storage order, it is possible to easily find a screen required for screen searching or searching.

Claims (15)

A control unit for controlling each unit; A detection sensor for detecting a subject and transmitting the detection signal to the controller; A photographing unit which generates a plurality of digitized frame images by intermittently photographing an area in which the subject is present a plurality of times as a photographing signal is input from the controller; A comparison unit configured to set a storage order by comparing the photographed plurality of frame images with a reference frame image; And And a memory manager to store the frame images in a memory according to the storage order. The method of claim 1, wherein the comparison unit, A surveillance camera device, characterized in that the frame image with the largest amount of image change is set to be an upper frame image. The method of claim 1, wherein the comparison unit, And dividing the frame image to be photographed into a plurality of regions, and setting the frame image having the greatest amount of image change in at least one specific region among the frame images to be an upper frame image. The method of claim 1, The detection sensor is a surveillance camera device, characterized in that installed to cover the angle of view of the photographing unit. The method of claim 4, wherein The detection sensor is a surveillance camera device, characterized in that provided in pairs on both sides of the camera lens of the photographing unit. The method according to any one of claims 1 to 5. And the memory management unit stores the frame image in the memory as much as the number of valid frames. The method according to any one of claims 1 to 3, The memory management unit deletes the remaining lower frame images except the upper frame images corresponding to the effective number of frames among the frame images previously recorded in the memory, and stores the frame images subsequently photographed in the storage area. Device. (a) detecting a subject; (b) generating a plurality of digitized frame images by intermittently photographing a plurality of regions in which the subject is present according to the detection of the subject; (c) setting a reference frame image; (d) calculating an amount of image change by comparing the reference frame image and the plurality of frame images, respectively; (e) determining a storage order of the frame images according to the amount of image change; And (f) storing the frame images in accordance with the determined storage order. The method of claim 8, The reference frame image is a surveillance camera operating method, characterized in that the subject is set as a frame image is detected by the sensor, but not photographed. The method of claim 8, And the reference frame image is set as a first frame image among the frame images photographed intermittently a plurality of times. The method of claim 8, Surveillance camera operating method, characterized in that in the step (d) the amount of change of the image is made by calculating the amount of change for each pixel. The method of claim 8, If the storage order is the same in the step (e), the surveillance camera operating method, characterized in that for setting the image having a large amount of image change in the center as the upper frame image. The method of claim 8, And storing the upper frame images corresponding to the preset valid frame number in step (f). The method of claim 8, And deleting the remaining lower frame images except the upper frame images corresponding to the effective number of frames among the first stored frame images and storing the second captured frame images. (a) detecting a subject; (b) generating a plurality of digitized frame images by intermittently photographing an area in which the subject is present a plurality of times according to the detection of the subject; (c) setting a reference frame image; (d) calculating an amount of image change by comparing the reference frame image and the plurality of frame images, respectively; (e) determining valid frame images according to the image variation amount; And (f) determining whether the storage capacity of the memory is exceeded, and if not, storing the photographed plurality of frame images; And (g) If in step (f) the storage capacity of the memory is exceeded, it is determined from the initial storage area of the memory whether the previously stored frame image is a valid frame image, and if it is not a valid frame image, it is deleted and the subsequent frame image. Storing the; the operating method of the surveillance camera comprising a.