KR101603212B1 - Control method of monitoring camera, and monitoring camera using the same - Google Patents

Abstract

The control method according to the present invention is a control method of a surveillance camera for generating a live-view image signal by photographing while controlling an exposure amount according to an average brightness to be applied as an ambient brightness, And (b). In step (a), a motion image is extracted. In step (b), the average luminance to be applied is obtained according to the area, the time of presence, and the average luminance of the extracted motion image.

Description

Technical Field [0001] The present invention relates to a control method of a surveillance camera and a surveillance camera using the surveillance camera,

The present invention relates to a control method of a surveillance camera and a surveillance camera using the surveillance camera, and more particularly, to a surveillance camera using a live-view video signal And a surveillance camera using the surveillance camera.

The surveillance cameras generate a live-view video signal by photographing while controlling the amount of exposure according to the average brightness to be applied as the ambient brightness. In addition, surveillance cameras communicate live-view video signals to computers as they communicate with computers as monitoring devices.

Here, surveillance cameras have a well-known motion tracking function. According to the motion tracking function, it is possible to detect a motion according to a change state of a live-view video signal, and to extract a detected motion image. Once the motion image is extracted, an alarm signal may be generated, or the motion image may be tracked by panning and tilting.

On the other hand, surveillance cameras control the amount of exposure to be inversely proportional to the average luminance to be applied as the ambient luminance, in order to generate a live-view image signal by photographing.

In conventional surveillance cameras, the average luminance of the entire screen or the center of the screen is calculated from the input video signal, and the calculated average luminance is set to the average luminance to be applied.

That is, according to the conventional surveillance cameras, although it has a motion tracking function, it can not actively control the exposure amount by using it. Accordingly, there is a problem that accuracy of motion tracking is low.

For example, when a person wearing black clothes in bright daylight appears on one side, the average luminance to be applied is calculated to be high, so that the amount of exposure is relatively low. In this case, motion tracking is possible.

However, when the person moves to the shadow of a tree, the average luminance to be applied is not so low, so the amount of exposure is not so high. In this case, motion tracking is impossible because the luminance difference between the tree shadow image and the human image is minute.

An object of the present invention is to provide a control method of a surveillance camera capable of increasing the accuracy of motion tracking by actively controlling the exposure amount using a motion tracking function and a surveillance camera using the surveillance camera .

A control method of the present invention is a control method of a surveillance camera that generates a live-view image signal by photographing while controlling an exposure amount according to an average brightness to be applied as ambient brightness, wherein steps (a) and (b).

In the step (a), a motion image is extracted.

In the step (b), the average luminance to be applied is obtained according to the area, the time, and the average luminance of the extracted motion image.

The surveillance camera of the present invention is a surveillance camera that generates a live-view video signal by photographing while controlling the exposure amount according to the average brightness to be applied as the ambient brightness. Here, the motion image is extracted, and the average brightness to be applied is obtained according to the area, the time of presence, and the average brightness of the extracted motion image.

According to the control method of the surveillance camera and the surveillance camera using the surveillance camera of the present invention, after the motion image is extracted by using the well-known motion tracking function, the area, the time and the average brightness The average luminance to be applied is obtained.

Accordingly, the accuracy of the motion tracking can be enhanced as the exposure control is actively performed using the motion tracking function.

For example, when a person wearing black clothes in bright daylight appears on one side, the average brightness to be applied is calculated to be slightly lower, so the exposure amount is slightly higher. In this case, motion tracking is possible.

In addition, when the person moves to the shadow of the tree, the average brightness to be applied is considerably lowered, so that the exposure amount also becomes considerably high. In this case, motion tracking is possible because the luminance difference between the tree shadow image and the human image becomes large.

1 is a block diagram showing a surveillance system to which surveillance cameras according to a first embodiment of the present invention are applied.
FIG. 2 is a view showing the appearance of a surveillance camera of FIG. 1;
3 is a block diagram showing the internal configuration of the surveillance camera of FIG.
4 is a flowchart illustrating a process of controlling the exposure amount by the digital signal processor as the main control unit of FIG. 3 while the motion tracking function is performed.
5 is a flowchart showing a detailed procedure of step S45 of FIG.
6 is a diagram for explaining a case where a plurality of motion images are extracted.
7 is a diagram showing the format of a look-up table (LUT) stored in the digital signal processor as the main control unit in FIG.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 shows a monitoring system to which surveillance cameras 1a, 1b and 1c according to the first embodiment of the present invention are applied.

Referring to FIG. 1, each of the surveillance cameras 1a, 1b, and 1c generates a live-view video signal by photographing.

In addition, monitoring each of cameras (1a, 1b, 1c) is in communication with the computer (3a, 3b, 3c) as the monitoring device via the communication channel (D _COM), live through the video signal channel (S _VID) - View (Live-view) video signals to the computers 3a, 3b, and 3c.

Fig. 2 shows the outline of one of the surveillance cameras 1a, 1b and 1c in Fig.

1, one of the surveillance cameras 1a, 1b and 1c is covered with a transparent cover 22 in front of the optical system OPS in order to protect the optical system OPS of the body 21 and to maintain cleanliness have.

FIG. 3 shows the internal structure of the body 21 of the surveillance camera 1a or 1b or 1c of FIG.

3, the surveillance camera 1a or 1b or 1c according to the present invention includes an optical system OPS, a photoelectric conversion unit OEC, a Correlation Double Sampler and Analog-to-Digital Converter (CDS-ADC) 301, A timing circuit 302, a digital signal processor (DSP) 307 as a control unit, a video-signal generating unit 308, a diaphragm motor M _A , a zoom motor M _Z , a focus motor M _F , A filter motor M _D , a panning motor M _p , a tilting motor M _T , a driving unit 310, a communication interface 112, a microcomputer 313 and an illumination unit 315.

An optical system (OPS) including a lens unit and a filter unit optically processes light from a subject.

The lens portion of the optical system OPS includes a zoom lens and a focus lens. In the filter section of the optical system (OPS), an optical low pass filter (OLPF) used in the night operation mode removes optical noise of a high frequency content. The IRF (Infra-Red Cut Filter) used in the daytime operation mode cuts off the infrared component of incident light.

A photoelectric conversion unit OEC of a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) converts light from the optical system OPS into an electrical analog signal. Here, the digital signal processor 307 controls the timing circuit 302 to control the operation of the photoelectric conversion unit OEC and the CDS-ADC (Correlation Double Sampler and Analog-to-Digital Converter) 301.

The CDS-ADC 101 processes an analog video signal from the photoelectric conversion unit OEC, removes the high-frequency noise, adjusts the amplitude, and converts the digital video data. The digital image data is input to the digital signal processor 307.

A digital signal processor 307 as a main control unit processes digital signals from the CDS-ADC device 101 to generate digital image data classified into luminance and chroma signals.

The video-signal generating unit 308 converts the digital video data from the digital signal processor 307 into a video signal (S _VID ) which is an analog video signal.

The digital signal processor 307 as the main control unit communicates with the computers (3a, 3b and 3c in Fig. 1) as host devices through the communication interface 312 and the communication channel (D _COM in Fig. 1) channel (s _VID) through a video-video signal _(VID s) from the signal generating unit 308 and transmits to the computer (3a, 3b, 3c).

The microcomputer 313 controls the driving unit 310 to drive the diaphragm motor M _A , the zoom motor M _Z , the focus motor M _F , the filter motor M _D , the panning motor M _P , And the tilting motor M _T. Further, the microcomputer 313 controls the illumination unit 315 to illuminate the transparent cover 22 with the illumination light.

The diaphragm motor M _A drives a diaphragm, the zoom motor M _Z drives a zoom lens, and the focus motor M _F drives a focus lens. The filter motor M _D drives the optical low-pass filter OLPF and the infrared cut filter IRF in the filter unit.

The panning motor M _P rotates the optical system OPS to the left and right. The tilting motor M _T rotates the optical system OPS up and down.

Meanwhile, the digital signal processor 307 as a main control unit performs a well-known motion tracking mode. That is, the digital signal processor 307 can detect a motion according to a change state of a live-view video signal, and extract a detected motion image. When the motion image is extracted, the digital signal processor 307 generates an alarm signal or tracks the motion image by panning and tilting control.

Here, the digital signal processor 307 obtains the average luminance to be applied as the surrounding luminance, and controls the exposure amount to be inversely proportional to the average luminance to be applied, according to the area, the time, and the average luminance of the extracted motion image.

More specifically, the average brightness to be applied is determined so that the average brightness of the extracted motion image is adjusted to be proportional to the area and the time of presence of the motion image, and is proportional to the average brightness of the adjusted result. This will be described in detail with reference to FIGS.

Accordingly, the accuracy of the motion tracking can be enhanced as the exposure control is actively performed using the motion tracking function.

For example, when a person wearing black clothes in bright daylight appears on one side, the average brightness to be applied is calculated to be slightly lower, so the exposure amount is slightly higher. In this case, motion tracking is possible.

In addition, when the person moves to the shadow of the tree, the average brightness to be applied is considerably lowered, so that the exposure amount also becomes considerably high. In this case, motion tracking is possible because the luminance difference between the tree shadow image and the human image becomes large.

4 shows a process in which the exposure amount is controlled by the digital signal processor 307 as the main control unit of FIG. 3 while the motion tracking function is performed.

Referring to FIGS. 3 and 4, the flow chart of FIG. 4 will be described as follows.

First, when motion is detected (step S41), the digital signal processor 307 determines whether or not it is a periodical motion (step S42). For reference, the movement in the wood area IN of FIG. 6 will be determined as a periodic movement due to a natural phenomenon.

Next, if it is not periodic motion in step S42, the digital signal processor 307 determines whether the area of the motion image is larger than the lower limit area (step S43). That is, it is determined whether or not the number of pixels of the motion image is larger than the lower limit number.

Next, if the area of the motion image is larger than the lower limit area in step S43, the digital signal processor 307 extracts the motion image (step S44).

Next, the digital signal processor 307 obtains the average luminance to be applied as the surrounding luminance according to the area, the time of presence, and the average luminance of the extracted motion image (step S45). Here, the average brightness of the extracted motion image is adjusted to be proportional to the area and the time of presence of the motion image, and the average brightness to be applied is determined so as to be proportional to the average brightness of the adjusted result.

Next, the digital signal processor 307 controls the exposure amount such that it is inversely proportional to the average luminance to be applied (step S46). That is, the digital signal processor 307 controls the opening angle and the shutter speed of the iris according to the average luminance to be applied.

All the above steps S41 to S46 are repeatedly performed until a termination signal is generated (step S47).

FIG. 5 shows a detailed procedure of step S45 of FIG. FIG. 6 is a diagram for explaining a case where a plurality of motion images IM1 to IM3 are extracted. In FIG. 6, reference symbol IN denotes a cyclic motion image according to a natural phenomenon (see step S41 in FIG. 4), IM1 to IM3 denotes a plurality of extracted motion images, and IB denotes a background image. FIG. 7 shows the format of a look-up table (LUT) stored in the digital signal processor 307 as the main control unit in FIG.

Referring to FIGS. 5 to 7, the detailed procedure of step S45 of FIG. 4 will be described as follows.

First, the digital signal processor 307 determines whether different motion images have been extracted (step S451).

If the single motion image is extracted in step S451, the digital signal processor 307 performs the following steps S452 to S454.

The digital signal processor 307 calculates the average luminance of the single motion image (step S452).

Next, the digital signal processor 307 reads, from the look-up table (LUT) of the internal memory, a weight value corresponding to the existence time and the area of the single motion image (step S453). In the look-up table (LUT), weight values proportional to the presence time and area of the motion image are stored (see FIG. 7).

Then, the digital signal processor 307 obtains the average luminance to be applied according to the average luminance of the background image, the weight of the single motion image, and the average luminance (step S454).

Here, the background image is an image of a region excluding the single motion image in the entire screen, and the weight value of the background image is set and applied in advance.

Also, the minimum value among the weight values stored in the look-up table (LUT) is larger than the weight value of the background image.

If the average luminance of the single motion image is MYs, the weight of the single motion image is Ws, the average luminance of the background image is MYb, and the weight of the background image is Wb, the average luminance Yout to be applied by Equation Is obtained.

Meanwhile, if the plurality of motion images IM1 to IM3 are extracted in step S451, the digital signal processor 307 performs the following steps S455 to S457.

The digital signal processor 307 calculates an average luminance of each of the plurality of motion images IM1 to IM3 (step S452).

Next, the digital signal processor 307 reads, from the look-up table (LUT) of the internal memory, a weight value corresponding to the existence time and the area for each of the plurality of motion images IM1 to IM3 (step S456).

In the look-up table (LUT), weight values proportional to the presence time and area of the motion image are stored (see FIG. 7). For example, if it is assumed in FIG. 6 that the existence times of the plurality of motion images IM1 to IM3 are the same, the weight of the first motion image IM1 is the largest and the weight of the third motion image IM1 is The least.

Finally, the digital signal processor 307 obtains the average luminance to be applied according to the average luminance of the background image, the weight of each of the plurality of motion images IM1 to IM3, and the average luminance (step S457).

Here, the background image IB is an image of a region excluding the plurality of motion images IM1 to IM3 on the entire screen, and the weight value of the background image is set and applied in advance.

Also, the minimum value among the weight values stored in the look-up table (LUT) is larger than the weight value of the background image IB.

6, when the average brightness of the first motion image IM1 is MY1, the weight of the first motion image IM1 is W1, the average brightness of the second motion image IM2 is MY2, The weight of the second motion image IM2 is W2, the average brightness of the third motion image IM3 is MY3, the weight of the third motion image IM3 is W3, the average brightness of the background image is MYb, Wb, the average luminance Yout to be applied by the following expression (2) is obtained.

As described above, according to the control method of the surveillance camera and the surveillance camera using the surveillance camera according to the present invention, after the motion image is extracted using the well-known motion tracking function, The average luminance to be applied is obtained according to the present time, and the average luminance.

Accordingly, the accuracy of the motion tracking can be enhanced as the exposure control is actively performed using the motion tracking function.

For example, when a person wearing black clothes in bright daylight appears on one side, the average brightness to be applied is calculated to be slightly lower, so the exposure amount is slightly higher. In this case, motion tracking is possible.

In addition, when the person moves to the shadow of the tree, the average brightness to be applied is considerably lowered, so that the exposure amount also becomes considerably high. In this case, motion tracking is possible because the luminance difference between the tree shadow image and the human image becomes large.

Although the present invention has been described with reference to the embodiments shown in the drawings, it is to be understood that various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

It can be used not only for surveillance cameras but also for all cameras capable of video recording.

1a, 1b, 1c ... surveillance cameras, 3a, 3b, 3c ... computers,
21 ... body, 22 ... transparent cover,
OPS ... Optical system, OEC ... Photoelectric conversion unit,
301 ... CDS-ADC, 302 ... timing circuit,
307 ... digital signal processor, 308 ... video-signal generator,
310 ... driver, 312 ... communication interface,
313 ... micro-computer, 315 ... illumination unit.
IN ... periodic motion images, IM1 to IM3 ... extracted motion images,
IB ... Background video.

Claims (15)

A control method of a surveillance camera for generating a live-view image signal by photographing while controlling an exposure amount according to an average brightness to be applied as an ambient brightness,
(a) extracting a motion image;
(b) calculating an average luminance of the extracted motion image;
(c) reading in a look-up table (LUT) a weight corresponding to the time and area of the motion image; And
(d) obtaining the average luminance to be applied according to the average luminance of the background image, the weight of the motion image, and the average luminance. delete delete The method according to claim 1,
The step (a)
(a1) if motion is detected, determining whether it is a periodical motion;
(a2) determining whether the area of the motion image is larger than the lower limit area, if it is not the periodic motion in the step (a1); And
(a3) extracting a motion image if the area of the motion image is larger than the lower limit area in the step (a2). delete delete delete delete delete delete delete delete delete A surveillance camera for generating a live-view image signal by photographing while controlling an exposure amount according to an average brightness to be applied as an ambient brightness,
A motion image is extracted,
Calculates an average luminance of the extracted motion image,
Up table (LUT), a weight corresponding to the existence time and area of the motion image,
Wherein the average luminance to be applied is determined according to an average luminance of the background image, a weight value of the motion image, and an average luminance. delete

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