JP4655879B2 - Noise component detector - Google Patents

Description

  The present invention relates to a noise component detection device, and more particularly to a noise component detection device capable of detecting a noise component contained in the composite signal without displaying a video based on the received NTSC composite signal and prompting the user to confirm the image. About.

Various proposals have already been made for a method of removing a noise component of an NTSC (National Television System Committee) composite signal. As one of such methods, a technique for acquiring a frame difference signal between a composite signal of a current frame and a composite signal of a previous frame and extracting a noise component included in the acquired frame difference signal has already been disclosed. (For example, refer to Patent Document 1).
JP-A-6-054235

  However, the technique disclosed in Patent Document 1 is effective only when the frame period is sufficiently shorter than the change period of the video. When the video changes significantly between the current frame and the previous frame, It is not suitable for images with only one frame.

  In the first place, the NTSC system itself was proposed as a transmission system for television video signals, and its main purpose is to show video to humans. In this way, when only aiming to show a video to a human being, it is not so much a problem that the NTSC composite signal has noise, and whether or not noise is present is also displayed on the display or the like. It can be understood by watching the video.

  That is, the problem is that noise is added to the NTSC composite signal. If it is not premised that the image is shown to humans, for example, the direction of the driver's face is monitored using the composite signal. This is the case. In such a case, in order not to output an inappropriate monitoring result, humans can detect whether noise is riding on the signal without looking at the display on the display, and perform some kind of fail safe. It is necessary to do so.

  The present invention has been made in view of the above circumstances, and can detect a noise component included in the composite signal without displaying a video based on the received composite signal of the NTSC system and prompting the user to confirm it. An object is to provide a noise component detection device.

In order to achieve the above object, a noise component detection apparatus according to a first aspect of the present invention includes an NTSC (National Television System Committee) composite signal receiving means, and the composite signal receiving means received by the composite signal receiving means. Vertical synchronization signal acquisition means for acquiring a vertical synchronization signal from a composite signal, and an output level for switching the level of a binary signal to be output in response to input of the vertical synchronization signal acquired by the vertical synchronization signal acquisition means A switching period measuring means for measuring a period from when the level of the binary signal is switched in a predetermined manner by the output level switching means until it is switched again in the same manner as the predetermined aspect; The difference between the measurement period by the switching period measurement means and the frame period in the NTSC system is a predetermined value. A switching period discriminating unit for discriminating whether or not the value falls within a value range; and when the switching period discriminating unit discriminates that the difference does not fall within a predetermined numerical range, the composite signal received by the composite signal receiving unit By determining that a noise component is included, a noise component detection unit that detects a noise component included in the composite signal, and a color difference signal is acquired from the video signal included in the composite signal received by the composite signal reception unit When the video signal is a monochrome video signal, the difference between the color difference value indicated by the color difference signal acquired by the color difference signal acquisition unit and the color difference value specific to the monochrome video is within a predetermined numerical range. and a color difference value determining means for determining whether the fall, the noise component detecting means, said color When the value discriminating unit discriminates that the difference does not fall within a predetermined numerical range, the composite signal received by the composite signal receiving unit discriminates that a noise component is included, and is included in the composite signal. A noise component is detected.

According to such a configuration, the difference between the measurement period by the switching period measurement means and the frame period in the NTSC system is a predetermined numerical value without displaying a video based on the received composite signal of the NTSC system and allowing the user to confirm it. By determining whether or not the signal falls within the range, a noise component included in the composite signal can be detected. Further, the difference between the color difference value indicated by the color difference signal acquired by the color difference signal acquisition unit and the color difference value specific to the monochrome video without displaying the video based on the received NTSC composite signal and allowing the user to check the video. Can be detected by determining whether or not is within a predetermined numerical range.

  In the noise component detection device, it is determined that the composite signal includes a noise component by the video signal acquisition unit that acquires the video signal from the composite signal received by the composite signal reception unit, and the noise component detection unit. In such a case, it may further comprise video use restriction means for restricting the use of the video based on the video signal acquired during the measurement period.

  According to such a configuration, when a noise component is included in the composite signal, it is possible to realize fail-safe such as restricting use of the video based on the video signal acquired during the measurement period. .

  The noise component detection device may further include a luminance signal acquisition unit that acquires a luminance signal from the video signal, and the video usage restriction unit includes a noise component in the composite signal by the noise component detection unit. When the determination is made, the monochrome signal based on the luminance signal acquired by the luminance signal acquisition unit may be restricted from being used.

  According to such a configuration, when a noise component is included in the composite signal, it is possible to realize fail-safe such as restricting use of the video based on the video signal acquired during the measurement period. .

Furthermore, a noise component detection method according to a second aspect of the present invention includes a composite signal receiving step for receiving a NTSC (National Television System Committee) composite signal, and vertical synchronization from the composite signal received by the composite signal receiving step. A vertical synchronization signal acquisition step for acquiring a signal; an output level switching step for switching a level of a binary signal to be output in response to the input of the vertical synchronization signal acquired by the vertical synchronization signal acquisition step; A switching period measuring step for measuring a period from when the level of the binary signal is switched in a predetermined manner by the output level switching step until it is switched again in the same manner as the predetermined manner; and the switching period measuring step Measurement period and frame period in the NTSC system Switching period determining step for determining whether or not the difference is within a predetermined numerical range, and when the difference is determined not to be within the predetermined numerical range by the switching period determining step, the composite signal reception By determining that the composite signal received in the step includes a noise component, a noise component detecting step for detecting the noise component included in the composite signal and the composite signal receiving step are included in the received composite signal A color difference signal acquisition step for acquiring a color difference signal from a video signal; and, when the video signal is a monochrome video signal, a color difference value indicated by the color difference signal acquired by the color difference signal acquisition step, a color difference value specific to the monochrome video, Color difference value determination to determine whether or not the difference between the values is within a predetermined numerical range Comprising a step, wherein the noise component detection step, when the difference by the color difference value determination step is judged to be not within a predetermined numerical range, including the noise component in the composite signal the composite signal receiving step has received By determining that the noise is included, a noise component included in the composite signal is detected.

Furthermore, a program according to a third aspect of the present invention is a computer that receives a composite signal reception procedure for receiving a NTSC (National Television System Committee) composite signal, and vertical synchronization from the composite signal received by the composite signal reception procedure. A vertical synchronization signal acquisition procedure for acquiring a signal, an output level switching procedure for switching the level of a binary signal to be output in response to the input of the vertical synchronization signal acquired by the vertical synchronization signal acquisition procedure, A switching period measuring procedure for measuring a period from when the level of the binary signal is switched in a predetermined manner by the output level switching procedure until it is switched again in the same manner as the predetermined manner; and the switching period measuring procedure The difference between the measurement period according to the above and the frame period in the NTSC system is a predetermined numerical range When it is determined that the difference is not within a predetermined numerical range by the switching period determination procedure for determining whether or not it is within the switching period determination procedure, a noise component is included in the composite signal received by the composite signal reception procedure. A noise component detection procedure for detecting a noise component included in the composite signal by determining that it is included, and a color difference signal for acquiring a color difference signal from a video signal included in the composite signal received by the composite signal reception procedure When the acquisition procedure and the video signal are monochrome video signals, the difference between the color difference value indicated by the color difference signal acquired by the color difference signal acquisition procedure and the color difference value unique to the monochrome video is within a predetermined numerical range. a color difference value determination procedure for determining whether dolphins not, is executed, the noise component detection step, the color difference value When it is determined that the difference does not fall within a predetermined numerical range by another procedure, the noise included in the composite signal is determined by determining that the composite signal received by the composite signal reception procedure includes a noise component. A component is detected.

  According to the present invention, it is possible to provide a noise component detection device capable of detecting a noise component included in a composite signal without displaying a video based on the received NTSC composite signal and prompting the user to confirm it. it can.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of a monitoring system according to the present embodiment. This monitoring system monitors the direction of the driver's face, and as shown in FIG. 1, is roughly composed of a camera 1, a capture module 2, and a CPU (Central Processing Unit) 3. The CPU 3 is connected to a ROM 31 and a RAM 32.

  The camera 1 is a monochrome camera adopting the NTSC (National Television System Committee) system, and as shown in FIG. 2, a synchronization signal generation circuit 11, a drive circuit 12, an imaging lens 13, an imaging element 14, The signal processing circuit 15 and the signal synthesis circuit 16 are configured.

  The synchronization signal generation circuit 11 generates a vertical synchronization signal and a horizontal synchronization signal. The vertical synchronization signal in this embodiment is output from the synchronization signal generation circuit 11 every field period (= 16.77 ms) so as to conform to the NTSC system.

  The drive circuit 12 synchronizes with the vertical synchronization signal generated from the synchronization signal generation circuit 11 to read out the imaging signals of the pixels of the odd-numbered lines among all the pixels of the imaging device 14, and all of the driving circuit 12. An even line readout signal for reading out an imaging signal of pixels of even lines among the pixels is supplied to the imaging element 14. The odd line read signal and the even line read signal are alternately output every time a vertical synchronizing signal is generated from the synchronizing signal generating circuit 11, in other words, every field period.

  The image sensor 14 is composed of, for example, a CCD (Charge Coupled Device) or the like, and a plurality of subject images input via the imaging lens 13, specifically, a driver's face image are arranged in a matrix. The pixels are photoelectrically converted and stored in these as an imaging signal. In addition, the image sensor 14 includes a vertical transfer register and a horizontal transfer register.

  The vertical transfer register is provided in each column of a plurality of pixels, and transfers the imaging signals accumulated in the pixels in the corresponding column in the vertical direction. The horizontal transfer register transfers the image signal for one line transferred by the vertical transfer register in the horizontal direction and outputs it.

  In response to the odd line read signal supplied from the drive circuit 12, the image sensor 14 supplies each pixel on the odd line to the vertical transfer register among all the pixels. On the other hand, when an odd line read signal is supplied from the drive circuit 12, each pixel in the odd line is supplied to the vertical transfer register among all the pixels. As a result, the imaging device 11 alternately outputs the imaging signals of the pixels of the odd lines and the imaging signals of the pixels of the even lines for each field period.

  The signal processing circuit 15 includes, for example, a CDS (Correlation Doubleness Sampling) circuit, an AGC (Automatic Gain Control) circuit, an AD (Analog / Digital) conversion circuit, a color process circuit, and the like. The signal processing circuit 15 performs a series of processes such as noise removal, level adjustment, A / D conversion, white balance adjustment, color separation, YUV conversion, and the like on the image pickup signal from the image pickup device 14 to obtain the luminance signal Y And a YUV signal including the color difference signals Cb and Cr is generated and output. Here, since the camera 1 in the present embodiment is a monochrome camera, the color difference values indicated by the color difference signals Cb and Cr are the color difference value “128” unique to the monochrome video.

  The signal mixing circuit 16 mixes the YUV signal generated by the signal processing circuit 15 with the vertical synchronization signal and the horizontal synchronization signal generated from the synchronization signal generation circuit 11, and uses the NTSC system as shown in FIG. A composite signal (NTSC signal) is generated and supplied to the capture module 2 via a cable.

  As shown in FIG. 4, the capture module 2 includes a signal separation circuit 21, an odd / even signal generation circuit 22, a selector 23, an odd field buffer 24, an even field buffer 25, a data processing circuit 26, 1 and second color difference subtracting circuits 27 and 28.

  The signal separation circuit 21 separates the NTSC signal supplied from the camera 1 via the cable into a YUV signal, a vertical synchronization signal, and a horizontal synchronization signal, and sends the vertical synchronization signal to the Odd / Even signal generation circuit 22. Are supplied to the selector 23, respectively.

  The Odd / Even signal generation circuit 22 is composed of, for example, a D-type lip flop circuit, and its clock terminal C is connected to the output terminal of the signal separation circuit 21. The positive phase output terminal Q of the Odd / Even signal generation circuit 22 is connected to one connection terminal of the AND circuit and the NOR circuit constituting the selector 23, and the negative phase output terminal (inverted output terminal) Q ( Bar) is connected to the input terminal D.

  The Odd / Even signal generation circuit 22 responds to a vertical synchronization signal supplied from the signal separation circuit 21 to the clock terminal C, and a signal fed back to the input terminal D from the reverse phase output terminal Q (bar). And latched and output from the positive phase output terminal Q. As a result, the Odd / Even signal generating circuit 22 outputs an Odd / Even signal that alternately switches between a high level and a low level for each field period as shown in FIG.

  The selector 23 includes, for example, an AND circuit, a NOT circuit, and a NOR circuit, and one input terminal of the AND circuit and an input terminal of the NOT circuit are connected to the output terminal of the signal separation circuit 21. The output terminal of the NOT circuit is connected to one of the input terminals of the NOR circuit, and the other input terminal of the AND circuit and the NOR circuit is connected to the positive phase output terminal Q of the Odd / Even signal generating circuit 22. Yes. The output terminal of the AND circuit is connected to the odd field buffer 24, and the output terminal of the NOR circuit is connected to the even field buffer 25.

  With this configuration, the selector 23 supplies the odd field buffer 24 with the YUV signal supplied from the signal separation circuit 21 when the Odd / Even signal supplied from the Odd / Even signal generation circuit 22 is at a high level. On the other hand, when the level is low, the even field buffer 25 can be supplied. As a result, the odd field buffer 24 is supplied with the YUV signal generated from the imaging signal of the odd line pixels, and the even field buffer 25 is supplied with the YUV signal generated from the imaging signal of the even line pixels. The Rukoto.

  The odd field buffer 24 and the even field buffer 25 are composed of, for example, an SDRAM (Synchronous Dynamic Random Access Memory) or the like. The odd field buffer 24 receives the YUV signal generated from the imaging signals of the pixels on the odd lines as an odd field. On the other hand, the even field buffer 25 stores the YUV signal generated from the imaging signals of the pixels of the even lines as even field data.

  The data processing circuit 26 mixes the odd field data and the even field data to generate a YUV signal for one frame, and separates the YUV signal into the luminance signal Y and the color difference signals Cb and Cr, and the luminance signal Y Are supplied to the CPU 3, the color difference signal Cb is supplied to the first color difference subtraction circuit 27, and the color difference signal Cr is supplied to the second color difference subtraction circuit 28.

  The first and second color difference subtracting circuits 27 and 28 subtract the color difference value “128” unique to the monochrome image from the color difference values indicated by the color difference signals Cb and Cr supplied from the data processing circuit 26, respectively, to obtain a subtraction value ΔCb. , ΔCr are supplied to the CPU 3.

  The CPU 3 shown in FIG. 1 controls various operations by appropriately executing various programs stored in the ROM 31 using the RAM 32 as a work memory. For example, the CPU 3 specifies the direction of the driver's face using a monochrome image based on the luminance signal Y as shown in FIG.

  The RAM 32 is provided with a falling interval timer that measures the time (falling interval) from when the falling edge of the Odd / Even signal is input until the next falling edge is input. When the falling edge of the Odd / Even signal is input to this falling interval timer, the timer initial value “0” is set, and thereafter, the falling interval timer is periodically counted up.

  The RAM 32 is provided with a frame counter that counts the number of frames. When the falling edge of the Odd / Even signal is input, the frame counter is incremented by “1”, and when the count value after addition reaches “N”, which is the upper limit value, The value “0” is set.

  Further, the RAM 32 is provided with an abnormality flag. The abnormality flag indicates that the difference ΔT between the time t indicated by the falling interval timer value when the falling edge of the Odd / Even signal is input and one frame period T (= 33.33 ms) is T1 ( For example, when it exceeds the range of about 0.2 to 0.3 ms (for example, ± 0.255 ms), the on state is set.

  Next, the abnormality determination process in the monitoring system having the above configuration will be described with reference to the drawings.

  FIG. 6 is a flowchart showing details of the abnormality determination process. When this process is started, as shown in FIG. 6, the CPU 3 first checks the input state from the Odd / Even signal generation circuit 22 to determine whether the falling edge of the Odd / Even signal has been input or not. Is determined (step S1). When the falling edge is input (step S1; Yes), the timer value is read from the falling interval timer provided in the RAM 32, and this time since the last falling edge of the Odd / Even signal was input. The time (falling interval) t until the falling edge is input is specified (step S2).

  Subsequently, the CPU 3 calculates a difference ΔT between the falling interval t specified in the process of step S2 and one frame period T (= 33.33 ms) (step S3), and the difference ΔT is ± T1. It is determined whether it is within the range (step S4). Here, when the difference ΔT exceeds the range of ± T1 (step S4; No), for example, as shown in FIG. 7 (A), a noise component is applied to the NTSC signal and a deviation occurs in the synchronization interval. And the abnormality flag provided in the RAM 32 is set to the on state (step S5 in FIG. 6). On the other hand, when the difference ΔT is within the range of ± T1 (step S4; Yes), the process of step S5 is skipped.

  Thereafter, the CPU 3 sets the timer initial value “0” in the falling interval timer (step S6), adds “1” to the value of the frame counter provided in the RAM 32 (step S7), and counts the value after the addition. Is determined to be “N” (for example, 4) which is the upper limit value (step S8). At this time, if the count value after the addition is “N” (step S8; Yes), the CPU 3 further determines whether or not the abnormality flag is on (step S9).

  If the abnormality flag is also on (step S9; Yes), the CPU 3 invalidates the luminance signal Y for the latest N frames among the luminance signals Y for a plurality of frames held in the RAM 32. As a result, the monochrome image based on the luminance signal Y is restricted (restricted) from being used (step S10). As a result, it is possible to prevent a monochrome image whose synchronization interval is shifted as shown in FIG. 5B from being used for specifying the driver's face orientation as a monitoring result. Thereafter, the CPU 3 clears the abnormality flag to turn it off (step S11 in FIG. 6), sets the counter initial value “0” in the frame counter (step S12), and then returns to the processing in step S1. Then, it waits for the falling edge of the next Odd / Even signal to be input (step S1; No).

  In contrast, when the value of the frame counter is a numerical value other than “N” (step S8; No), or when the abnormality flag is off (step S9; No), the first and second color difference subtraction is performed. It is determined whether or not the subtraction values ΔCb and ΔCr supplied from the circuits 27 and 28 are within a range of ± 64 (steps S13 and S14). Here, when at least one of the subtraction values ΔCb and ΔCr exceeds the range of ± 64, for example, when the subtraction value ΔCb is “230” and the subtraction value ΔCr is “210” (step S13; Yes, step S14; Yes), as shown in FIG. 7B, it is determined that a noise component has been added to the NTSC signal, and the latest luminance signal Y of a plurality of frames held in the RAM 32 is included. By deleting the luminance signal Y for one frame as invalid, the monochrome image based on the luminance signal Y is restricted from being used (step S15 in FIG. 6). Thereafter, the CPU 3 returns to the process of step S1 and waits for the next falling edge of the Odd / Even signal to be input (step S1; No).

  On the other hand, when the subtraction values ΔCb and ΔCr are both within the range of ± 64 (step S13; Yes, step S14; Yes), it is determined that no abnormality has occurred, and the process of step S1 is performed. And waits for the next falling edge of the Odd / Even signal to be input (step S1; No).

  As described above, according to the monitoring system of the present embodiment, the fall interval t and 1 are displayed without displaying a monochrome image based on the luminance signal Y on a display or the like to allow the driver or other occupants to check. By determining whether or not the difference ΔT between the frame period T (= 33.33 ms) is within the range of ± T1, the noise component included in the NTSC signal can be detected. If a noise component is included in the NTSC signal for the most recent N frames, the luminance signal Y for the most recent N frames out of the luminance signals Y for a plurality of frames held in the RAM 32 is invalidated. By deleting as a thing, the fail safe of restrict | limiting not to use the monochrome image based on these luminance signals Y is realizable.

  Further, according to this monitoring system, it is determined whether or not the differences ΔCb and ΔCr between the color difference values indicated by the color difference signals Cb and Cr and the color difference value “128” unique to the monochrome image are within a range of ± 64. Thus, the noise component included in the NTSC signal can be detected. If the NTSC signal for the most recent N frames includes a noise component, the luminance signal Y for the most recent frame among the luminance signals Y for a plurality of frames held in the AM 32 is invalidated. By deleting as a thing, the fail sale which restrict | limits not using a monochrome image based on this luminance signal Y is realizable.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation and application are possible. Hereinafter, modifications of the above-described embodiment applicable to the present invention will be described.

  In the above embodiment, the noise component detection device of the present invention has been described by taking the monitoring system for identifying the face direction of the driver as an example. However, the present invention is not limited to this, and the NTSC signal of monochrome video is used. It is arbitrary as long as it performs some kind of measurement.

  The numerical values, configurations, and flowcharts shown in the above embodiment are merely examples, and can be changed or modified as appropriate.

  In the above embodiment, the program executed by the CPU 3 is stored in advance in the ROM 31 or the like. However, this invention is not limited to this, You may make it function as monitoring which concerns on the said embodiment by applying the program for performing the above-mentioned process to the existing monitoring system.

  The method of providing such a program is arbitrary. For example, the program may be provided via a communication medium such as the Internet, or may be distributed by being stored in a recording medium such as a CD-ROM or DVD-ROM. .

It is a block diagram which shows the structural example of the monitoring system which concerns on embodiment of this invention. It is a block diagram which shows the structural example of the camera shown in FIG. It is a figure which illustrates the waveform of the NTSC signal in the normal time, and an Odd / Even signal. It is a block diagram which shows the structural example of the capture module shown in FIG. (A) is a figure which illustrates the monochrome image at the time of normality, (B) is a figure which illustrates the monochrome image at the time of abnormality. It is a flowchart which shows the detail of an abnormality determination process. (A) is a figure which illustrates the waveform of the NTSC signal and Odd / Even signal at the time of abnormality, (B) is a figure which expands and illustrates the waveform of the NTSC signal at the time of abnormality.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Camera 2 ... Capture module 3 ... CPU (switching period discrimination | determination means, noise component detection means, image | video use restriction means, color difference value discrimination means)
DESCRIPTION OF SYMBOLS 11 ... Synchronization signal generation circuit 12 ... Drive circuit 13 ... Imaging lens 14 ... Imaging element 15 ... Signal processing circuit 16 ... Signal synthesis circuit 21 ... Signal separation circuit (Composite signal receiving means, vertical synchronization signal acquisition means, video signal acquisition means)
22 ... Odd / Even signal generation circuit (output level switching means)
DESCRIPTION OF SYMBOLS 23 ... Selector 24 ... Odd field buffer 25 ... Even field buffer 26 ... Data processing circuit (color difference signal acquisition means, luminance signal acquisition means)
27... First color difference subtraction circuit 28... Second color difference subtraction circuit 31.
32 ... RAM (switching period measuring means)

Claims (3)

Composite signal receiving means for receiving NTSC (National Television System Committee) composite signal;
Vertical synchronization signal acquisition means for acquiring a vertical synchronization signal from the composite signal received by the composite signal reception means;
An output level switching means for switching the level of the binary signal to be output in response to the input of the vertical synchronization signal acquired by the vertical synchronization signal acquiring means;
A switching period measuring means for measuring a period from when the level of the binary signal is switched in a predetermined manner by the output level switching means until it is switched again in the same manner as the predetermined manner;
Switching period determining means for determining whether or not the difference between the measurement period by the switching period measuring means and the frame period in the NTSC system is within a predetermined numerical range;
When it is determined by the switching period determining means that the difference does not fall within a predetermined numerical range, the composite signal received by the composite signal receiving means determines that a noise component is included in the composite signal. Noise component detection means for detecting the included noise component;
Color difference signal acquisition means for acquiring a color difference signal from a video signal included in the composite signal received by the composite signal reception means;
When the video signal is a monochrome video signal, whether or not the difference between the color difference value indicated by the color difference signal acquired by the color difference signal acquisition unit and the color difference value specific to the monochrome video is within a predetermined numerical range. Color difference value determining means for determining;
Equipped with a,
The noise component detection means includes
When the color difference value determining means determines that the difference does not fall within a predetermined numerical range, the composite signal received by the composite signal receiving means determines that the noise component is included in the composite signal. Detects the noise component included,
Noise component detecting device you wherein a. Video signal acquisition means for acquiring a video signal from the composite signal received by the composite signal reception means;
When it is determined by the noise component detection means that a noise component is included in the composite signal, video use restriction means for restricting the use of the video based on the video signal acquired during the measurement period;
The noise component detection apparatus according to claim 1, further comprising: Further comprising a luminance signal acquisition means for acquiring a luminance signal from the video signal;
The video use restriction means is
When it is determined that the noise component is included in the composite signal by the noise component detection unit, the monochrome signal based on the luminance signal acquired by the luminance signal acquisition unit is restricted from being used.
The noise component detection apparatus according to claim 1 or 2 ,

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