KR101510111B1 - Cctv systems with a color control at low intensity - Google Patents

Abstract

The present invention relates to a CC TV system having a color control function at low light. In the CC TV system having a lens, an image signal processor, and a codec, the image signal processor is characterized in that the image signal processor comprises: a digital slow speed shutter control device which can perform a function to control an exposure time so that an object is photographed in a way that touches feelings; a digital noise attenuator that can suppress noises via digital signal processing so as to set a range that does not leave a residual image at a low light mode and can perform a function to determine an attenuation degree of the noise; a gamma controller that can maintain a LCD mode in the day time and can perform a function to change a condition upon detection of nighttime through an automatic gain controller in order to increase a low light sensitivity; and an automatic gain controller that can perform a function to adjust automatically the gain to a maximum value capable of recognizing easily an object.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a CCTV system having a color control function,

The present invention relates to a closed-circuit television (CCTV) system having a low-illuminance color control function. More specifically, the present invention can identify a color through an increase in exposure time, an increase in low- And more particularly to a CCTV system having a color control function at low illumination, which prevents the discrimination of a subject from being hindered.

Generally, a CCTV camera (closed-circuit television camera) is an image-capturing device that can detect a place or an object that is photographed by shooting a specific place or object and sending it to a closed-circuit television. It is managed by a building, a parking lot, In addition to general surveillance cameras for enhancing the efficiency of expense, it is used for automobile safety devices, etc., and the use thereof is greatly diversified.

On the other hand, CCTV is inevitably operated in a dark place, that is, in low light, for the purpose of use, and in this case, an infrared camera is used or a light of a visible ray area is used.

Particularly, in the conventional security surveillance camera (Day & Night), it is switched to a monochrome screen in order to increase the sensitivity of the low-illuminance image, and the discrimination of the color is remarkably deteriorated and the image drag and after- So that it is difficult for the surveillant to distinguish the subject.

That is, the conventional security surveillance camera (Day & Night) uses a color CCD (Charge Coupled Device) at the same time in daytime and nighttime, reproduces images in color in the daytime, There is a problem that the discrimination of the color is remarkably deteriorated and the monitor can not accurately distinguish the subject due to the image dragging phenomenon and the afterimage phenomenon caused by raising the sensitivity of the low illuminance image.

In addition, there are various methods for responding to changes in illumination depending on the season, time, and location of the CCTV camera, and factors affecting object identification such as clouds, snow, rain, and fog. to be.

On the other hand, even in such a variety of methods, there is a problem that the noise is maximized and the image quality is lowered. In particular, when the shutter speed is set to a maximum at the nighttime, the reflected light may cause image data to be damaged.

In addition, while the camera generally has the advantage of displaying a clear color shape during the daytime shooting, there is a problem that the color noise due to the color burst is displayed at the time of night shooting, A problem arises in that the focus is changed due to different wavelengths of the visible light and the infrared light band.

Accordingly, Korean Patent Registration No. 10-1169017 discloses that "installed on the front surface of a body so as to be able to take a picture of the front side, has a CdS for sensing the illuminance of the surroundings and a remote control receiver for receiving an external radio signal, An encoder (ENCODER) for converting a digital image signal transmitted from a high-resolution CMOS camera into an analog signal through a signal processing algorithm stored in a first EEPROM, a CCD An AGC (Auto Gain Control) for automatically controlling a gain of an analog video signal transmitted from a camera, and an ISP (Image Signal) for converting a signal controlled by the AGC to a data value stored in a second EEPROM and converting the signal to a video signal, A first and a second video amplifier for amplifying signals output from the encoder and the ISP, MP and a video switch for switching the amplified signals of the first and second video amplifiers in accordance with the control signal of the CdS circuit part for the daytime and the nighttime switching, Surveillance camera "has been proposed.

Korean Patent No. 10-1322829 discloses " a digital camera for photographing a target object and generating an image file; And an automatic correction device connected to the digital camera for correcting an exposure of the digital camera in response to a sunrise sunset so that an image file is corrected according to the illuminance of the surrounding environment, An exposure correction module for correcting an exposure of the camera according to a sunrise time and a sunset time extracted from the sunrise sunset time extraction module for collecting a sunrise time and a sunset time of the setting area from the stored sunrise time DB, A CCTV system consisting of "

However, in the surveillance camera of the day / night automatic switching system using the high-resolution CMOS camera having the above-described configuration, when the color is reproduced at night, the color noise causes a problem in identifying the subject. In this situation, The problem of color reproducibility and the sensitivity of the subject at night are lowered, which is also a problem in object identification.

That is, in the conventional CCTV camera, the color is switched to black and white by eliminating the color noise, and the sensitivity is increased in the black and white screen state.

Patent Document 1: Korean Patent Publication No. 10-1169017 (July 20, 2012) Patent Document 2: Korean Patent Publication No. 10-1322829 (Oct. 22, 2013) Patent Document 3: Korean Patent Registration No. 10-0934433 (December 21, 2009) Patent Document 4: Korean Patent Registration No. 10-1141844 (Apr. 24, 2012)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems of the related art, and it is an object of the present invention to provide an image display apparatus and a display apparatus which are capable of reducing the discrimination of color by switching to a monochrome screen in order to increase the sensitivity of existing low- In order to prevent the surveillance person from being distracted by the dragging and after-image phenomenon, the important factor of the CCTV camera is to accurately identify the subject, so that the nighttime sensitivity, which is the inevitable factor for increasing the discrimination, Color noise suppressor, low-light sensitivity enhancer, and low-noise noise attenuator to improve color reproduction, it is possible to output a color image of a subject to be monitored, thereby providing a color control function The purpose of the CCTV system is to provide All.

It is an object of the present invention to provide a CCTV system including a lens, an image sensor, an image signal processor, an illuminance sensor, an IR light source, and a codec, wherein the image signal processor includes: A digital noise attenuator that attenuates noise within a range of 80% of the total noise in order to suppress noise in the low illuminance mode of 0.05 to 0.08 lux or less by suppressing noise by digital signal processing, To maintain the LCD mode during the day and to increase the low-light sensitivity, the output gamma of the image is applied to the 0.55 gamma of the image in the case of recognizing the night through the automatic gain controller, and the gamma is adjusted by applying 0.35 gamma in the low- A gamma controller for detecting a signal level input from the image sensor, And a color controller for determining a range of the current sensor gain and outputting a color suppression gain after receiving the current sensor gain currently set from the image sensor and an automatic gain controller for lowering the gain when the gain is higher than the reference level, , And the digital slow shutter controller is operated so that the number of output frames is not less than 7 frames per second in order to prevent the occurrence of dragging in a low lightness mode of 0.05 to 0.08 (LUX) or less, Whether the current sensor gain is smaller than the minimum sensor gain (Smin), whether the current sensor gain is greater than the minimum sensor gain and less than the maximum sensor gain (Smax), and whether or not the current sensor gain It is determined whether the sensor gain is larger than the maximum sensor gain, and if the current sensor gain is smaller than the minimum sensor gain, Set are not a first color suppression gain (a ₀₎ and, if the current sensor gain is a value less than the minimum sensor gain, rather than a large maximum sensor gain is and suppress the color through linear interpolation based on the current sensor gain, the current sensor gain If a value greater than the maximum sensor gain is set in (a ₂₎ a third color exciter me to investigate and suppressing as much as possible the color of the IR light source, and at least the sensor gain at the time of low illuminance, characterized in that a small value less than the maximum sensor gain Can be achieved by a CCTV system having a color control function.

As described above, according to the CCTV system having the color control function in the low illumination condition of the present invention, as described above, the CCTV system including the lens, the image sensor, the image signal processor and the codec, It is determined whether the illuminance of the signal is in a low illuminance state. If it is determined that the illuminance is low, the exposure time of the image sensor is adjusted. Subsequently, a subroutine is executed to adjust the low illuminant color according to the gain value of the image taken at low illuminance , The low light intensity is attenuated and the low light image output gamma is adjusted so that the CCTV is operated under low light conditions so that even if the exposure time is increased, the low light sensitivity is raised, and the noise is removed, The low-illuminance CCTV system A very useful inventions, etc., etc., which can dramatically improve the reliability of the product and intended use.

1 is a block diagram of a CCTV system having a color control function in a low-illuminated state to which the present invention is applied.
2 is a flow chart for explaining the method of the present invention.
3 is a flow chart for explaining the low illuminance color adjustment subroutine of FIG. 2;
4 is a graph showing an exposure control method performed in a digital slow shutter controller in an ISP.
5 is a detailed block diagram of an ISP among a low-illuminance CCTV system to which the present invention is applied.
Fig. 6 is a detailed block diagram of the digital noise attenuator shown in Fig. 5. Fig.
7 is an exemplary graph for controlling the video output depreciation in the gamma controller in the ISP.
8 is a block diagram of a codec according to the present invention;
9 is a graph showing a form in which an exposure time is controlled by an ISP.
10 is a graph showing a color suppression period in the present invention.
11 (a) to 11 (d) are graphs showing respective areas when color is suppressed in ISP according to the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It is to be understood that the present invention is not intended to be limited to the specific embodiments but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.

1 is a block diagram of a CCTV system having a color control function in a low illumination state in which the present invention is applied.

First, the color sensitivity is 1.5 (LUX) and black and white is 0.15 (LUX) in general CCTV, and the color image is much lower than the monochrome image at night shooting. Therefore, even in the case of color CCTV, There is a case in which a monochrome image is obtained.

However, according to the present invention, a color image is implemented even in a range of 0.05 to 0.08 (LUX) or less, a gain value of AGC (Auto Gain Control) exceeds a maximum sensor gain Smax, a resistance value of an illuminance sensor does not exceed a maximum resistance value Rmax To provide a technique for implementing color images.

1, the CCTV system having the low illuminance color control function to which the present invention is applied includes a lens 10, an image sensor 20, an illuminance sensor 13, an IR light source 15, an image signal processor (Hereinafter referred to as "ISP") 30 and a codec 40.

In addition, an image finally generated through the codec 40 is coded in an image format such as H.264 or H.265, and then transmitted to a necessary place through the wired / wireless communication network 50.

At this time, the wired / wireless communication network 50 may be a variety of communication networks such as Internet, Ethernet, and Wi-fi, as well as a communication module.

Meanwhile, among the components of the CCTV system having the color control function in the low illuminance state according to the present invention, the lens 10 is preferably used with a good performance lens, but a general lens (Fixed type or Varifocal type) May be applied.

The image sensor 20 may have a resolution of more than 1.5M pixels having a resolution of 1440x1024, and a higher resolution may provide a better effect.

However, a color of 270K or 410K pixels, which reproduces 480 or 600 TV lines, is also acceptable. In addition, HD cameras having high resolutions such as 1027 X 768, 1280 X 960, and 1920 X 1080 may be employed for a clearer picture.

In addition, a signal photographed through the image sensor 20 is transmitted to the ISP 30.

The color noise is appropriately removed through the color suppression in the illuminance where the ISP 30 can generate color noise.

FIG. 5 is a detailed block diagram of the ISP of the low-illuminance CCTV system to which the present invention is applied, and FIG. 6 is a detailed block diagram of the digital noise attenuator of FIG.

In the ISP (Image Signal Processor) 30, an image signal photographed at a low illuminance output from the image sensor 20 is subjected to a predetermined algorithm to generate an image signal capable of color identification That is, FIG. 2 and FIG. 3 are performed as an example.

The ISP 30 includes a digital slow shutter controller 31, a digital noise reducer 32, a gamma controller 33 and an auto gain controller (AGC) ) 34, a color controller 35, and the like.

In addition, the lens 10, which is an optical part used in the present invention, uses a general lens (Fixed type or Varifocal type) of F2.0 or more and the image sensor 20 needs to maintain a sensitivity of at least 800 mV or more.

On the other hand, the digital slow shutter controller 31 in the ISP 30 performs a function of adjusting the exposure time so that the subject can be photographed in a sensible manner. In order not to cause a drag in the low light mode of 0.05 to 0.08 (LUX) It is preferable that the number of frames to be outputted is 7 frames or more per second.

4 is a graph showing an exposure control method performed by the digital slow shutter controller in the ISP. The digital slow shutter controller 31 controls the digital slow shutter controller 31 based on the control of the microcomputer (not shown) in the digital slow shutter controller 31, Y), i.e., controlling the entire exposure based on a value representing the current brightness.

The main contents of the present invention focuses on the color reproducibility in the gray area, that is, the low light area of FIG. 4, and shows how the camera performs the entire exposure control.

If it is brightened in a completely dark state, it will be controlled by Slow Shutter -> Gain -> Iris -> Shutter. In case of going from low to light level, Shutter -> Iris -> Gain - > Slow Shutter. In this case, the relationship between bright and dark is determined based on the luminance component (Y), and the degree of low light is considered to be started from the stage where the gain is applied.

For example, in the case of a sensor, it means Long Exposure Time. If the shutter value is 1/60 at 720p / 60, 4 frames long Exposure Time is 16.67ms (1/60) * 4 = 66.68ms About 15 fps).

The digital noise attenuator 32 includes a 2D-NR 321 and a 3D-NR 322 and suppresses noises by digital signal processing to set a range in which no residual image remains in the low light mode, As shown in FIG.

At this time, the 2D-NR (321) compares a predetermined reference frame and two previous frames among a plurality of image frames sequentially input through the digital slow shutter controller 31 to attenuate noise corresponding to the deviation When the noise attenuation is increased in the 2D-NR (321), the total noise attenuation is about 10% in order to prevent the adverse effect of deteriorating the resolution in proportion to the degree of noise attenuation.

In addition, the 3D-NR 322 compares three frames among the sequentially input image frames in a state where the primary noise is attenuated through the 2D-NR 321, and noise is attenuated corresponding to the deviation In the 3D-NR 322, when the degree of noise attenuation is increased, 70% of total noise attenuation is taken so as to prevent the adverse effects of image dragging and afterimage.

That is, the digital noise attenuator 32 sets a range in which no residual image remains in the low illuminance mode at 0.05 to 0.08 lux, and the noise is attenuated using both the 3D-NR 322 and the 2D-NR 321 , And it is designed to adjust sensitivity by day / night.

In addition, the gamma controller 33 maintains the LCD mode during the daytime and performs a function of changing the condition when recognizing the nighttime through the AGC gain in order to increase the low-illuminance sensitivity. The AGC senses the signal level input from the image sensor and raises the gain when it is smaller than the reference level, and lowers the gain when it is higher than the reference level.

For example, the condition for recognizing the nighttime is to apply the luminance and gain values at the same time. The gamma of the standard LCD is usually 1.0, but the modified 0.55 gamma is applied while tuning, and the gain is about 27.3 If the luminance is less than about 4 lux, it is regarded as nighttime, and the gamma value is 0.35 gamma.

In addition, the automatic gain controller 34 performs a function of setting a maximum value that facilitates the classification of a subject, in which a large number of dot noises are generated according to an increase amount of gain, which is an essential element of low luminance sensitivity.

In addition, the CODEC 40 compares three frames among image frames sequentially input in a state where the noise is attenuated secondarily through the 3DNR 322 in the digital noise attenuator 32, NR (41) for attenuating the noise, so that 20% of total noise attenuation is taken in order to prevent degradation of resolving power, thereby attenuating the noise in a tertiary manner and outputting it as a final video signal.

That is, in the CCTV system having the color control function at the time of low illumination in which the present invention is applied, the ISP 30 performs the entire image signal processing (signal processing for converting the captured image into a color image and an afterimage- And the codec 40 performs about 20% of the total video signal processing.

At this time, the dragging and the residual image of the image are displayed when the noise reduction is strengthened through the 3D-NR 41 in the codec 40. The degree of noise attenuation in the image is adjusted through the primary to tertiary noise attenuator So that there is no adverse effect such as dragging and afterimage of the image.

In addition, although not shown in FIG. 1, a video amplifier or the like may be further provided so that the video signal can be amplified and output to the outside.

2 is a flow chart for explaining the method of the present invention. When the CCTV starts to operate (S1), based on a video signal input through the lens 10 and the image sensor 20, ) To perform a predetermined algorithm.

First, the ISP 30 determines whether the image signal transmitted through the image sensor 20 is in a low light state (for example, 0.05 to 0.08 (LUX) or less) (S2) 20 as shown in Fig. 9 (S3).

At this time, the determination of the low illuminance is determined by the gain value of the image sensor reflected on the separate image or by the visible light sensor, and the exposure control performed by the digital slow shutter controller 31 shown in Fig. As shown in the graph of the method, when the step of controlling the exposure of the camera proceeds to Shutter -> Iris -> Gain, it is judged that it is low when entering the gain step.

FIG. 9 is a graph showing a state in which the ISP 30 controls the exposure time (when x8 is set to the maximum gain relative to the minimum gain x1). When the brightness becomes dark or bright in the long exposure period The exposure time of the image sensor 20 is moved along the curve section of the blue color.

Subsequently, the ISP 30 performs low-illuminance color adjustment (S4) through the color controller (35) and low-noise noise attenuation through the digital noise attenuator (32) The luminance image output gamma adjustment is performed (S6).

Here, in order to enhance the contrast of the image, the output gamma of the image is adjusted by using compression gamma as shown in Fig. 7 (a) in a normal situation (in a bright situation) Pattern and high brightness area can be expressed evenly.

As a result, it is possible to identify the color through the process of performing the above-described steps in the ISP 30 at the low illuminance, complete the process of converting the image into the image capable of identifying the moving subject, Or if it is determined in step S2 that the low illuminance is not obtained, the algorithm is terminated (S7).

Fig. 3 shows a flow chart for explaining the low illuminance color adjustment subroutine S4 in Fig. Generally, in order to suppress the generation of color noise during low illumination, suppression is applied to each color. At this time, the illuminance is determined by the gain value reflected on the image, and the degree of suppression of color is determined by linear interpolation Has adopted.

In order to increase the expressive power of color in the low illuminance section, color suppression should be controlled with respect to color noise. In order to reduce color noise and maximize the expressive power of color, as shown in the graph of the color suppression section of the present invention shown in FIG. 10, Are separated into four steps, and the respective regions are suppressed for each color as shown in Figs. 11 (a) to 11 (d). For convenience, step (a) is referred to as a general illumination mode, step (b) as a low illumination entry mode, step (c) as a low illumination duration mode, and step (d) as a minimum illumination mode.

The reason for separating each step in this way is that the degree of color suppression at each step must also be changed because the size of the noise changes depending on the degree of the gain, so that the reproducibility of the color versus the color noise can be controlled.

FIG. 11 is a graph showing each region when suppressing color in the ISP according to the present invention, and is tuned for each illuminance by adjusting the color suppression gain as described above.

In other words, conventionally, by applying the fixed gain value, the color suppression can not maintain the color expressive power evenly with respect to the noise. However, in the present invention, the color expressive power relative to the noise can be uniformly maintained through the color controller 35, Linear interpolation method was used.

FIG. 11A shows an area in which a maximum color suppression gain is used to express a color because it is determined that the general illumination mode is not included and a large amount of color noise is not included, and is controlled by Equation 1 in Equation (1). The area (b) of FIG. 11 is controlled in accordance with the expression (2) of Equation (1) so as to suppress the color suppression gain by suppressing the color suppression gain by judging the low- do. The region (c) of FIG. 11 is discriminated as a low-luminance continuous mode in which the low-luminance region is increased and the color noise is increased, and the color suppression gain is controlled by Expression 3 in Equation (1). The region (d) in FIG. 11 is a region determined as the lowest illumination mode and is controlled by Formula 4 in Equation (1). The color adjustment for Equation (1) is performed by the color controller (35) in the ISP (30). The color controller 35 receives the current sensor gain from the image sensor, and then determines the range of the current sensor gain and adjusts the appropriate color suppression gain.

As described above, when the ISP 30 performs color suppression, the color disappears. At this time, the color reproduction is smooth by tuning the color suppression gain of the low-level city. For reference, the color suppression gain is processed without leaving the color with a large value, and the image with a small value is processed with a color close to black and white.

The principle of low illumination color adjustment will be described with reference to FIG. 3 and FIGS. 10 and 11 (a) to 11 (d).

First, when the ISP 30 adjusts the exposure time of the sensor (S3) and performs color adjustment (S4) (S40), the current image sensor gain value Scur is smaller than the predetermined minimum sensor gain value Smin (S45) or smaller than the predetermined sensor gain (Smid) and smaller than the predetermined maximum sensor gain (Smax) or smaller than the predetermined sensor gain (Smid) (Step S49) or greater than the predetermined maximum sensor gain Smax (step S53).

If the ISP 30 determines the size of the gain value Scur of the current image sensor adjusted by the AGC to be less than or equal to the predetermined minimum sensor gain Smin (Yes in S41), the ISP 30 determines the general illumination mode The color suppression gain constant is maintained at the maximum (S43). That is, if the current gain value Scur recognizing the illuminance is less than or equal to the minimum sensor gain Smin, the maximum color suppression gain is maintained without color correction.

If the current gain value Scur is larger than the predetermined minimum sensor gain Smin (No in S41) and smaller than or equal to the intermediate sensor gain Smid (Yes in S45), the output value of the illuminance sensor is smaller than the minimum resistance value R_LOW (S46). The illuminance sensor is generally called a CdS sensor, and outputs a higher resistance value as it is darker. The reason why the output value of the illuminance sensor is further determined by adding step S46 is that when the image sensor is a black color object such as a black curtain, it is determined that the image is in the low light intensity entry step To eliminate the error. If it is determined in step S46 that the output value of the roughness sensor is greater than the minimum resistance value Rmin, the roughness level is set to the entry mode (S47). Otherwise, the roughness mode is processed. In the low-illuminance entry mode, the low-illuminance color suppression gain is linearly interpolated according to Equation 2 of Equation 1 according to the change of the image (S47). That is, if the present gain value Scur is larger than the minimum sensor gain Smin and smaller than or equal to the intermediate sensor gain Smid (see FIG. 11 (b)), As shown in FIG. 10 (b), the linear interpolation for correcting the color signal due to the degradation of the luminance is performed by interpolating the value of the color gain in accordance with the variation of the illuminance of the area.

If the magnitude of the current gain value is greater than the intermediate sensor gain Smid (No in S45) and the maximum sensor gain Smax is less than the maximum sensor gain Smax (Yes in S49) The low luminance color gain is linearly interpolated according to the change of the image according to the equation (3) of FIG. 10 (c) and the equation (1) (S51). That is, if the current gain value Scur is larger than the intermediate sensor gain Smid and smaller than or equal to the maximum sensor gain Smax (see FIG. 11 (c)), As shown in FIG. 10 (c), the value of the color gain is interpolated and applied according to the variation of the illuminance of the corresponding region.

If the ISP 30 determines that the current value of the gain value Scur is greater than the maximum sensor gain Smax (see (d) in FIG. 10, Yes in S53), the resistance value of the illuminance sensor is greater than the maximum resistance value (S55). The reason why the step S55 is added is to eliminate the case where the sensor value of the AGC indicates a higher value (in the case of recognizing a darker state) than the illuminance at the time of photographing when a black color object is photographed as described above. If the determination result in step S55 is true, the process is performed in the lowest illumination mode according to equation (4) in the equation (1) (S57). If the result of the determination in step S55 is false, the low-luminance continuous mode is processed (S51). That is, if the present gain value Scur is greater than the maximum sensor gain Smax and the output value of the illuminance sensor is greater than the maximum resistance value Rmax, it is regarded as a completely dark state, The gain is kept at the minimum value so as to be photographed in black and white. The algorithm execution for each mode reduction low color adjustment is terminated (S49).

In other words, the color adjustment method performed by the ISP 30 is such that if the current image sensor gain value set in the AGC is smaller than or equal to the predetermined minimum sensor gain (Smin, for example, Approx.1 [dB]), And the maximum color suppression gain is used to maintain the AGC color gain at almost the original value.

However, when the illuminance changes in a darker state (low-entry mode), that is, when the current image sensor gain value set in the AGC is larger than the minimum sensor gain Smin and the predetermined intermediate sensor gain Smid (for example, Approx. 35.1 [dB]), the color gain corresponding to the current illumination is applied, but the linear interpolation is performed to correct the color signal to the degradation of the illuminance.

If the current image sensor gain value set in the AGC is larger than the intermediate sensor gain Smdi and smaller than the maximum sensor gain Smax (for example, Approx. 35.1 [dB]), In the same case, linear interpolation is performed on the color gain to suppress the increase of the color noise. When the current image sensor gain value is larger than the maximum sensor gain (Smax), the illumination is regarded as a completely dark state, To maintain the minimum value.

The criteria of the minimum sensor gain (Smin), the intermediate sensor gain (Smid), and the maximum sensor gain (Smax) described above are shown in Table 1.

Sensor gain classification Image Sensor Gain [dB]
Analog gain + Digital gain Minimum sensor gain (Smin) Approx. 1 [dB] Medium Sensor Gain (Smid) Approx. 35.1 [dB] Maximum sensor gain (Smax) Approx. 35.1 [dB]

In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or software constituent units. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

10: Lens 20: Image oath
30: Image signal processor (referred to as "ISP")
31: Digital Slow Shutter Controller 32: Digital Noise Attenuator
341: 2D-NR 342: 3D-NR
33: gamma controller 34: automatic gain controller
35: color controller 40: codec
41: 3D-NR 50: wired / wireless communication unit

Claims (3)

1. A CCTV system having a lens, an image sensor, an image signal processor, an illuminance sensor, an IR light source, and a codec,
The image signal processor comprising:
A digital slow shutter controller for adjusting an exposure time for photographing a subject,
A digital noise attenuator that attenuates noise within a range of 80% of the total noise so that no residual image is left in a low-illuminance mode of 0.05 to 0.08 lux or less by suppressing noise by digital signal processing,
To maintain the LCD mode during the day and to increase the low-light sensitivity, the output gamma of the image is applied to the 0.55 gamma of the image in the case of recognizing the night through the automatic gain controller, and the gamma is adjusted by applying 0.35 gamma in the low- A gamma controller,
An automatic gain controller for detecting a signal level input from the image sensor and raising the gain when the signal level is lower than the reference level and lowering the gain when the signal level is higher than the reference level,
And a color controller for receiving a current sensor gain currently set from the image sensor and outputting a color suppression gain by determining a range of the current sensor gain,
The digital slow shutter controller is operated so that the number of output frames is not less than 7 frames per second in order to prevent dragging in a low lightness mode of 0.05 to 0.08 (LUX)
Wherein the color controller obtains the current sensor gain from the image sensor and determines whether the current sensor gain is less than the minimum sensor gain Smin, whether the current sensor gain is greater than the minimum sensor gain and less than the maximum sensor gain Smax And determines whether or not the current sensor gain is greater than the maximum sensor gain. If the current sensor gain is smaller than the minimum sensor gain, the first color suppression gain a ₀ that does not suppress the color is set, If the sensor gain is greater than the minimum sensor gain and less than the maximum sensor gain, the color is suppressed through linear interpolation according to the current sensor gain. If the current sensor gain is greater than the maximum sensor gain, setting the third color exciter me of (a ₂₎ to suppress, and the minimum sensor gain is color control at the time of low illuminance, which is smaller than the maximum value of the sensor gain CCTV system with.
The method according to claim 1,
Whether the current sensor gain is greater than the minimum sensor gain and less than or equal to the maximum sensor gain Smax is determined by determining whether the current sensor gain is greater than the minimum sensor gain and less than the first intervening value Smid, Whether the sensor gain is greater than the first inter-value and less than or equal to the maximum sensor gain,
If the current sensor gain is greater than the minimum sensor gain and less than the maximum sensor gain, suppressing the color through linear interpolation according to the current sensor gain means that the current sensor gain is greater than the minimum sensor gain and less than the maximum sensor gain (Smax) The second-color suppression gain is set according to the following formula (1), and when the current sensor gain is larger than the first-interval value and less than the maximum sensor gain, the second- And the first interim value is a value located between a minimum sensor gain and a maximum sensor gain, wherein the first interim value is a value located between a minimum sensor gain and a maximum sensor gain.
Note 1

Reference expression 2

3. The method according to claim 1 or 2,
The digital noise attenuator
A 2D-NR which compares a predetermined reference frame and two previous frames among a plurality of image frames input sequentially through the digital slow shutter controller and attenuates a primary noise corresponding to the deviation;
And a 3D-NR, which compares three sequentially input image frames in a state where the first-order noise is attenuated through the 2D-NR, and attenuates the second-order noise corresponding to the deviation, CCTV system with color control function.

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