JP2013172320A - Detection system, signal processing method therefor, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide; a detection system capable of correcting a detected position and obtaining the brightness information of a photo-object perpetually and accurately even in a case where positional and directional shifts occur between an imaging device and the position of the photo-object that is a detection target; a signal processing method for the system; and a program.SOLUTION: A detection system includes: a position storage part 144 capable of storing information related to a position including a detection range of plural photo-object images; and a photo-object position determination part 17 capable of searching detection information obtained by a determination part 16 for position and size of the photo-object in all images to determine the position of the photo-object including a detection range, and storing the detection information including the detection range related to the photo-object in the position storage part. Further, the photo-object position determination part 17 includes a tracking process function of tracking whether a shift in the detection position has occurred and correcting the positional information of the position storage part while adjusting a correcting state and time by matching the elapsed time of a positional shift.

Description

  The present invention relates to a detection system that detects the state of a subject using an imaging device or the like, a signal processing method thereof, and a program, for example.

For example, an imaging apparatus used in a nighttime crime prevention system shown in Patent Document 1 has been proposed.
This imaging apparatus has a signal processing unit, and the light source has a frequency higher than 100 Hz or 120 Hz (when a commercial power source of 50 Hz or 60 Hz is used as the power source, the brightness of the light source fluctuates at 100 Hz or 120 Hz that is twice that). Modulate with high frequency. Further, the signal processing unit has a detection unit for detecting the high frequency modulation signal.
However, this imaging apparatus needs to have a frame rate higher than its modulation frequency.

By the way, a standard called NTSC (National Television Standards Committee) system or PAL (Phase Alternating Line) system is adopted for imaging apparatuses which are widely spread in general.
Since an image pickup apparatus adopting such a standard has a low frame rate, for example, it cannot be used as an image pickup apparatus for a crime prevention system as shown in Patent Document 1.

Therefore, a detection system that can detect a light source or the state of a subject irradiated with the light source and can be applied to a crime prevention system adopting a standard such as NTSC has been proposed (see Patent Document 2).
This detection system detects the state of the subject of the frequency component of the light source.

Japanese Patent No. 3019309 JP 2008-141251 A

However, the detection system has the following disadvantages.
Even if the position and orientation of the subject and the imaging device are fixed so that they remain stationary when one or more subjects are detected and stored, the position and orientation of each subject will change due to secular change. There may be slight deviations.
As a result, it is difficult for the detection system to acquire and measure luminance information permanently and accurately due to the difference from the stored position information.

Conventionally, as a position detection method, a detection method using comparison based on a background difference is known.
However, with this method, particularly when a plurality of subjects are detected, it is easy to detect moving objects and floating objects other than the target subject, and it is difficult to determine the target subject.

  In addition to being able to detect the state of the light source or the subject irradiated with the light source, the present invention corrects the detection position even when a position and orientation shift occurs between the position of the subject to be detected and the imaging device. It is therefore an object of the present invention to provide a detection system capable of obtaining luminance information of a subject permanently and with high accuracy, and a signal processing method and program thereof.

  A detection system according to a first aspect of the present invention includes a light source, an imaging device that images the light source or a subject irradiated with the light source, an analysis processing unit that performs an analysis process on a signal acquired from the imaging device, A determination unit that detects and determines the state of the light source or the subject based on an analysis result of the analysis processing unit, a position storage unit that can store information about positions including detection ranges in the images of a plurality of subjects, and the determination unit From the obtained detection information, the position and size of the subject in all images are searched to determine the position of the subject including the detection range, the detection information including the detection range related to the subject is acquired, and the detection information is A subject position determination unit that can be stored in the position storage unit as information relating to the position, and the subject position determination unit tracks whether or not a detection position shift has occurred. A tracking processing function that corrects the position information of the position storage unit while adjusting the correction state and time according to the elapsed time, and the analysis processing unit performs the above-described analysis processing unit from the imaging device for each predetermined scanning plane cycle. Obtaining a signal, obtaining a time average of the signal level difference from the signal level difference of the signal between a plurality of different scanning planes, and performing an analysis process for performing a predetermined calculation based on the value of the time average, The calculation result of the analysis process is output to the determination unit, and when the detection information is stored in the position storage unit, the analysis process is selectively performed on an image in the detection position range specified in the detection information. I do.

  A signal processing method of a detection system according to a second aspect of the present invention includes an imaging step of imaging a light source or a subject irradiated with the light source with an imaging device, a signal acquired from the imaging device every predetermined scanning plane period, and a plurality of signals An analysis processing step of performing an analysis process for obtaining a time average of the signal level difference from the signal level difference of the signal between different scanning planes, and further performing a predetermined calculation based on the value of the time average; A determination step for detecting and determining the state of the light source or subject based on the analysis result of the step, and a detection range including a detection range by searching for the position and size of the subject in all images from the detection information obtained in the determination step A subject that determines the position of the subject, acquires detection information including a detection range related to the subject, and stores the detection information in the position storage unit as information about the position A position determination step, and in the subject position determination step, tracking is performed to determine whether or not a detection position shift has occurred, and the position storage is performed while adjusting the correction state and time according to the elapsed time of the position shift. A tracking processing step for correcting the position information of the part, and in the analysis processing step, when the detection information is stored in the position storage unit, the image of the detection position range specified in the detection information Selectively performing the analysis process.

  According to a third aspect of the present invention, an image pickup process for picking up a light source or a subject irradiated with the light source with an image pickup device, a signal is acquired for each predetermined scan plane period, and a signal of the signal between a plurality of different scan planes Calculates the time average of the signal level difference from the level difference, and further performs analysis processing for performing a predetermined calculation based on the value of the time average, and detects and determines the state of the light source or subject based on the analysis result of the analysis processing And the detection information obtained by the determination process, the position and size of the subject in all images are searched to determine the position of the subject including the detection range, and the detection information including the detection range related to the subject is obtained. A subject position determination process for acquiring and storing the detection information in the position storage unit as information on the position. In the subject position determination process, whether the detection position has shifted. Including tracking processing for correcting the position information in the position storage unit while adjusting the correction state and time according to the elapsed time of the positional deviation, and in the analysis processing, the position storage unit detects the detection When information is stored, the program causes a computer to execute signal processing of a detection system including processing for selectively performing the analysis processing on an image in a detection position range specified in the detection information.

  According to the present invention, not only can the state of the light source or the subject irradiated to the light source be detected, but also the detection position can be corrected even when a position and orientation shift occurs between the position of the subject to be detected and the imaging device. As a result, the luminance information of the subject can be obtained permanently and with high accuracy.

It is a figure which shows the structural example of the detection system which concerns on embodiment of this invention. It is a figure which shows an example of the information table preserve | saved in the position memory | storage part which concerns on this embodiment. It is a figure which shows notionally the state before the position determination of the to-be-photographed object in the to-be-photographed object position determination part which concerns on this embodiment, and the state after position determination. It is a figure which shows an example of the (x, y) width table information of the detection range referred in order to perform position determination in the to-be-photographed object position determination part which concerns on this embodiment. It is a flowchart for demonstrating specifically the detection position determination process in the to-be-photographed object position determination part which concerns on this embodiment, Comprising: It is a figure which shows the process in the case of performing a position determination process. It is a flowchart for demonstrating specifically the detection position determination process in the to-be-photographed object position determination part which concerns on this embodiment, Comprising: It is a figure which shows a process when not performing a position determination process. It is a figure for demonstrating the search method of the object of one light source or reflected light. It is a figure for demonstrating the fine adjustment process of a detection range. It is a figure which shows the example of formation of the tracking time table stored in a position search information storage part. It is a figure for demonstrating the relationship between the shift direction of a to-be-photographed object and a tracking time table. It is a flowchart for demonstrating the basic tracking process of the number No of the detection position memory of a position memory | storage part. It is a flowchart for demonstrating the 2nd tracking process of the number No of the detection position memory of a position memory | storage part. It is a flowchart for demonstrating the 3rd tracking process of the number No of the detection position memory of a position memory | storage part. It is a figure which shows an example for demonstrating the structure of CCD which concerns on this embodiment. It is a figure for demonstrating the time series of CCD of FIG. It is a figure which shows the example of an arrangement | sequence of the pixel of a single plate complementary color filter type CCD. It is a figure which shows an example of the combination of the color signal in odd field OFD and even field EFD. It is a timing chart for demonstrating the signal processing method of the luminance signal of the light source analysis process part which concerns on this embodiment. It is a figure which shows the waveform W6 about the frequency component contained in a light source. It is a figure which shows an example of the relationship between duty ratio D and square sum SACBD. It is a flowchart figure for demonstrating a series of operation | movement outline | summary of the detection system which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating a configuration example of a detection system according to an embodiment of the present invention.

The detection system 10 includes a light source 11, an imaging device 12, a luminance signal extraction unit 13, a light source analysis processing unit 14, a filter processing unit 15, a determination unit 16, a subject position determination unit 17, and a timer processing unit 18.
The light source analysis processing unit 14 includes a first calculation unit (A) 141, a second calculation unit (B) 142, a calculation processing unit (time average square sum calculation processing unit) 143, and a position storage unit 144.
The subject position determination unit 17 includes a position search processing unit 171, a position search information storage unit 172, and a tracking processing unit 173.

As will be described later in detail, the tracking processing unit 173 performs a tracking process for correcting a search position that is caused by a secular change or an environmental change.
That is, the detection system 10 includes a tracking processing unit 173 in the subject position determination unit 17, and in the detection of the state of the light source or the subject irradiated with the light source, the detection system 10 extends over a long period between the position of the subject to be detected and the imaging device. Even if there is a position and orientation shift caused by aging and environmental conditions, the brightness information of the subject can be obtained by correcting the detection position while adjusting the correction state and time according to the elapsed time. It is configured so that it can be obtained permanently with high accuracy.

  The light source 11 illuminates the subject with a predetermined luminance. The luminance of the light source 11 is variable, and the luminance within the charge accumulation time of the imaging element included in the imaging device 12 changes at a period 4n times the field period of the imaging device 12. Here, n = 1, 2, 3,.

The imaging device 12 used in the detection system 10 according to the present embodiment employs an imaging device having the following specifications.
As an example of the imaging device constituting the imaging apparatus 12, a single-plate complementary color filter and a field storage type interline transfer CCD (Charge Coupled Device) image sensor (hereinafter simply referred to as a CCD) are used.
As an example, the television system of the imaging device 12 employs the NTSC system, the scanning system employs interlace, the scanning frequency is 15.734 KHz, and the vertical frequency is 59.94 Hz.
The imaging device 12 having such a configuration images the light source 11 or the subject illuminated by the light source 11 and outputs a signal obtained by the imaging to the luminance signal extraction unit 13.
Although a CCD image sensor is illustrated here, a CMOS image sensor can also be applied.

The luminance signal extraction unit 13 extracts a luminance signal from the input signal and outputs the luminance signal to the first calculation unit 141 and the second calculation unit 142 of the light source analysis processing unit 14.
The luminance signal extracted by the luminance signal extraction unit 13 is adjusted to a signal level optimized for calculation.
The signal level needs to be a signal level that does not overflow in the output values of the first calculation unit 141, the second calculation unit 142, and the calculation processing unit 143. Therefore, the luminance signal extraction unit 13 includes a circuit that adjusts the luminance signal level.
The adjustment value of the luminance signal level may have a table capable of mode switching when there are several modes. The mode may be a video signal standard such as NTSC or PAL, or a frequency mode of the imaging apparatus.

In the light source analysis processing unit 14, the first calculation unit 141 obtains the time average of the level difference of the luminance signal in the m-th and (m + 2) -th fields in the same area of the imaging device.
The output result A of the first calculation unit 141 is output to the calculation processing unit 143.
The second calculation unit 142 obtains a time average of the level difference of the luminance signal in the (m + 1) th and (m + 3) th fields in the same region of the input luminance signal.
The output result B of the second calculation unit 142 is output to the calculation processing unit 143.
The details of the operations of the first calculation unit 141 and the second calculation unit 142 will be described later.
The first calculation unit 141 and the second calculation unit 142 perform calculation processing in accordance with calculation range designation information for analyzing the image stored in the position storage unit 144.

The output result A and the output result B output from the first calculation unit 141 and the second calculation unit 142, respectively, are input to the calculation processing unit 143.
The arithmetic processing unit 143 obtains a square sum value (A ² + B ² ) of the output result and outputs it to the filter processing unit 15.
The arithmetic processing unit 143 performs arithmetic processing according to the calculation range designation information for analyzing the image stored in the position storage unit 144.

The position storage unit 144 stores, for example, detection information on the positions and sizes of a plurality of subjects detected with high accuracy by removing unnecessary moving objects from the signal component of the light source, which is determined by the subject position determination unit 17.
As described above, the light source analysis processing unit 14 includes the position storage unit 144 that can specify a calculation range for image analysis of the first calculation unit 141 and the second calculation unit 142.
The position storage unit 144 can store a plurality (n) pieces of position information.
Therefore, the detection processing of the light source analysis processing unit 14 is performed in the range of the image specified by the position storage unit 144 (for example, the range Mn = [x1, y1-x2, y2]) in the detection of the light source or the subject irradiated to the light source. One piece of analysis processing is performed within one frame.
Alternatively, if n analysis processes cannot be performed within the time of one frame, the analysis process performed in one frame is set to a (a <n), and n analysis processes are performed over a plurality of frames. It does not matter how to do.
An image in the n designated ranges obtained by the analysis process can be acquired as a detected image if there is a light source or a subject irradiated with the light source.

The light source analysis processing unit 14 has a mode capable of detecting only the range stored in the position storage unit 144 and a mode for all images.
Since the detection range is not specified in the initial state in which position information or the like is not stored in the position storage unit 144, the light source analysis processing unit 14 performs light source analysis processing on the entire image instead of selective detection processing.

Further, when the position storage unit 144 is a nonvolatile memory or a setting file, the detection position can be restored without being affected by a power failure. In addition, it has a flag for selecting whether or not to determine the subject position.
A part of the position storage unit 144 has a volatile memory and can be used for temporary storage.
The position storage unit 144 has a function of storing information such as the position coordinates and size of the subject, the frequency detection sensitivity (signal level) of the subject, and the individual number of the subject.

  FIG. 2 is a diagram illustrating an example of an information table stored in the position storage unit 144 according to the present embodiment.

In FIG. 2, “No” indicates the individual number of the subject. “X, y” indicates the start position coordinates of the subject, and “xe, ye” indicates the end position coordinates of the subject. “N” indicates a number corresponding to the number of subjects. “Level” indicates a signal level (signal intensity) which is frequency sensitivity of the subject.
In this example of the table TBL1, the subject of “No. 1” is the first subject with the start position coordinates “10, 10” and the end position coordinates “20, 20”, and the signal level is relatively high. “40”.
The subject of “No. 2” is the second subject whose start position coordinates are “30, 30” and end position coordinates are “50, 60”, and its signal level is relatively “43”.
The “No. 3” subject is the third subject whose start position coordinates are “100, 100” and end position coordinates are “120, 120”, and its signal level is relatively “50”.
The subject of “No. 4” is the fourth subject having a start position coordinate of “300, 300” and an end position coordinate of “325, 315”, and its signal level is relatively “60”.

As described above, the light source analysis processing unit 14 of the present embodiment includes the position storage unit 144 that is a memory (detection position memory) that can store information on the positions of a plurality of subjects, and the position storage unit 144 stores subject positions. It has object detection information such as the coordinate value of the image area shown and the object number.
The light source analysis processing unit 14 has a function of analyzing (detecting) an image in the detection position range specified by the coordinates when the detection position coordinates stored in the position storage unit 144 exist.
The subject position determination unit 17 stores the detection information in the position storage unit 144.
The detected position information stored in the position storage unit 144 is the detected position corrected by the subject position determining unit 17 so that high-precision luminance information can be stably measured even over time. Contains information.

The light source analysis processing unit 14 is, for example, two modes that are designated by a control system (not shown) or automatically switched according to the presence or absence of detection information in the position storage unit 144, specifically, an all-pixel detection mode and a subject position detection mode. It is possible to operate with.
In the all-pixel detection mode, the light source analysis processing unit 14 does not specify a detection range in the initial state where position information or the like is not stored in the position storage unit 144. Perform analysis processing.
Based on the detection result in the all-pixel detection mode, the subject position determination unit 17 described later detects information regarding the positions of a plurality of subjects, and the detection information is stored in the position storage unit 144.
For example, when this detection information is stored in the position storage unit 144, the light source analysis processing unit 14 switches from the all-pixel detection mode to the subject position detection mode.
In the subject position detection mode, the light source analysis processing unit 14 analyzes (detects) an image in the detection position range specified by the coordinates based on the detection position coordinates and the like stored in the position storage unit 144.
Since the light source analysis processing unit 14 is included, the detection system 10 can detect only the light source 11 or the position of the subject irradiated on the light source 11 and does not detect the position to be excluded as a subject. The effect is also effective and can be detected with high accuracy.

In the initial state described above, the filter processing unit 15 performs noise reduction on the entire image by filter processing and outputs the noise to the determination unit 16.
The filter processing unit 15 performs noise reduction on the n detected images in the light source analysis processing unit 14 or eliminates a portion that has not been detected by the filter processing, and outputs the result to the determination unit 16.

In the above-described initial state, the determination unit 16 is output from the arithmetic processing unit 143 and based on the square sum value (A ² + B ² ) of the entire image that has been reduced in noise by the filter processing unit 15. For example, it is determined whether the subject imaged is stationary or moving. Details of the operation of the determination unit 16 will be described later.
Based on the square sum value (A ² + B ² ) of the detected image that is output from the arithmetic processing unit 143 and from which the filter processing unit 15 has eliminated noise and has not been detected, the determination unit 16 For example, it is determined whether the subject imaged at 12 is stationary or moving. Details of the operation of the determination unit 16 will be described later.

The subject position determination unit 17 includes a position search processing unit 171, a position search information storage unit 172, and a tracking processing unit 173 that search the position of the subject from all the images based on the detection state obtained by the determination unit 16. .
The position search information storage unit 172 stores the position search result of the position search processing unit 171 and stores tracking progress information including a tracking time table in which information is tabulated by the tracking processing of the tracking processing unit 173.
The tracking processing unit 173 corrects the positional shift even if there is a long-term secular change or a positional shift caused by an environmental condition between the position of the subject to be detected and the imaging apparatus. It has a function of correcting the position while adjusting the correction state and time according to the time.

  Hereinafter, the subject position determination process in the subject position determination unit 17 and the process of correcting the detected position information in accordance with the tracking process will be described in more detail.

FIGS. 3A and 3B are diagrams conceptually showing states before and after the position of a subject in the subject position determination unit according to the present embodiment.
As shown in FIG. 3A, the subjects OBJ1 and OBJ2 before the position determination are searched, and as shown in FIG. The position is determined, and the range becomes the analysis target of the light source analysis processing unit 14 and the detection target of the determination unit 16.
Detection information such as the range after the position determination is stored in the position storage unit 144 of the light source analysis processing unit 14. In the present embodiment, as described above, there are a subject position detection mode in which only the detection of the range is possible and an all image detection mode for all images.
For example, in an application where it is necessary to detect only a subject at a specific position, the operation is performed in the subject position detection mode in the range stored in the position storage unit 144.
In that case, as described above, in order to set a specific position, the subject position determination unit 17 first searches the subject target position and stores it in the position storage unit 144, and thereafter only the detection of the stored position is performed. Applicable for use.

The subject position determination unit 17 determines the detection range from the size of the subject.
In the subject position determination unit 17, the detection range is determined using the first mode when the (x, y) width of the detection range DTRG is fixed to one and the (x, y) width according to the size of the subject. Second, a table value detection range DTRG having a size exceeding (or below) the current (x, y) width is selected from a plurality of tables prepared in advance with a (x, y) width. There are two modes:
The (x, y) width table of the detection range DTRG is stored in the position search information storage unit 172, for example.
The subject position determination unit 17 can select either the first mode or the second mode, and has a configuration having these functions.
This detection range is determined from a table in which the size of the subject is prepared in advance and the detection range is determined, so that the size and position of the subject can be detected at high speed.

  FIG. 4 is a diagram illustrating an example of (x, y) width table information of the detection range referred to for position determination in the subject position determination unit 17 according to the present embodiment.

In FIG. 4, “No” indicates the number of (x, y) width information of the subject detection range. “X, y” indicates the size information of the object detection range DTRG, and sBlK indicates the number of search blocks (number of pixels).
In the example of the (x, y) width table TBL2, the detection range DTRG of “No. 1” is “10 × 10” and the number of blocks is “2”.
The detection range DTRG of “No. 2” is “30 × 30” and the number of blocks is “4”.
The detection range DTRG of “No. 3” is “100 × 100” and the number of blocks is “8”.
The detection range DTRG of “No. 4” is “300 × 300” and the number of blocks is “12”.
The position search processing unit 171 of the subject position determination unit 17 refers to the (x, y) width table TBL2, and searches, for example, in ascending order from the smaller “No” or in descending order from the larger “No”. The detection range most suitable for the target subject is determined.

The subject position determination unit 17 is configured to be able to finely adjust the detection range DTRG from the size of the subject.
For fine adjustment of the detection range, from the state in which the detection range DTRG (x, y) is determined, the fine adjustment value table prepared in advance or the fine adjustment formula [x1 = x * sP1, y1 = y * sP2] x, y) The configuration has a function of finely adjusting the width.
Here, “sP1” and “sP2” are adjustment parameters and take values of, for example, 1 <sP1, sP2 <2.
With this function, even if a small shake or movement occurs in a subject that can be detected within the normal detection range, it can be detected without departing from the subject range.
This is particularly effective when the subject is a light source.

Next, the detection position determination process in the subject position determination unit 17 according to the present embodiment will be specifically described with reference to FIGS.
5 and 6 are flowcharts for specifically explaining the detection position determination process in the subject position determination unit 17 according to the present embodiment, and FIG. 5 is a flowchart in the case of performing the position determination process. FIG. 6 is a flowchart when the position determination process is not performed.
FIG. 7 is a diagram for explaining a method of searching for a subject of one light source or reflected light.
FIG. 8 is a diagram for explaining detection range fine adjustment processing.
The following processing is performed mainly by the position search processing unit 171. Here, the processing will be described as processing by the subject position determination unit 17.

The subject position determination unit 17 determines whether or not to perform position determination processing (ST1).
When the subject position determination unit 17 determines that the position determination process is to be performed in step ST1, the subject position determination unit 17 performs detection (search) with reference to the (x, y) width table TBL2 stored in the position search information storage unit 172. The (x, y) width of the range DTRG is determined (ST2).
Then, for example, the subject position determination unit 17 clears the storage area for information on the detected position in the position storage unit 144 of the light source analysis processing unit 14 (ST3).
Next, the subject position determination unit 17 investigates the number of pixels of the target frequency with the (x, y) width of the detection range DTRG (ST4).

The process in step ST4 will be described with reference to FIGS.
The subject position determination unit 17 refers to the (x, y) width table TBL2 and searches for a subject of one light source or reflected light by a method as shown in FIGS.
First, as shown in FIG. 7A, the minimum unit of search is one block BLK.
FIG. 7A shows a 2 × 2 case as an example of a vertical × horizontal search pixel spix.
The detection intensity of one block is a value obtained by dividing the sum of all pixels by 2 × 2.
Here, the search is started.

As shown in FIG. 7B, one horizontal line LLN search process is performed.
In this case, the search block sblk = 2, and the 2 × 2 block is searched for the horizontal line (x direction) LLN.
When the search block sblk is 2, since it is vertical (y) 2 and horizontal (x) 2, the number of detected blocks is counted.
If the block BLK is detected by the blocks indicated by reference numerals 2, 3, and 4, the count value is 3.
In the case of a table in which the number of search blocks sblk is large, the subject position determination unit 17 repeats the process with reference to the next number sblk in the detection range table until the count value becomes 1.
Information on the detected horizontal line LLN is stored in the position search information storage unit 172.
The subject position determination unit 17 searches the entire process for every 2 × 2 blocks in the above process.
Next, one vertical line search process is performed.

As shown in FIG. 7C, one vertical line VLN search process is performed.
The subject position determination unit 17 searches the detection line of the horizontal line LLN stored in the position search information storage unit 172 with a block width indicated by the number of search blocks sblk in the vertical direction.
The search method is the same as the search of the horizontal line LLN. In the case of a table in which the number of search blocks sblk is large, the process is repeated with reference to the next number sblk in the detection range table until the count value becomes 1.
The detected vertical line VLN is stored in the position search information storage unit 172.
The subject position determination unit 17 searches the entire process for every 2 × 2 blocks in the above process.
Next, a search process for the detection range DTRG is performed.

As shown in FIG. 7D, the detection process of the detection range DTRG is performed.
A continuous vertical and horizontal block detected by the horizontal line LLN and the vertical line VLN from the above processing is defined as one range.
The total average value of the detection intensities of the blocks in the range is obtained.
Next, the detection range DTRG is determined.
Also in this case, continuous vertical and horizontal blocks that can be detected by the horizontal line LLN and the vertical line VLN from the above processing are set as one range.
The total average value of the detection intensities of the blocks in the range is obtained.
Then, the subject position determination unit 17 determines the detection range [(x, y) − (xe, ye)] DTRG.
Then, fine adjustment is performed within the determination range with the magnification of the fine adjustment parameters sP1 and sP2.
The above processing can be performed simultaneously with a plurality of light sources.

The subject position determination unit 17 performs fine adjustment processing of the detection range DTRG by a method as shown in FIGS.
The subject position determination unit 17 finely adjusts the detection intensity in each determination range, investigates the detection intensity in four directions or eight directions for each detection range, and finally determines the detection intensity in a place with the highest detection intensity.
In this example, the detection intensity on one block is investigated in FIG. 8 (B), the detection intensity on the right of one block is investigated in FIG. 8 (C), and the detection intensity below one block is examined in FIG. 8 (D). Then, in FIG. 8E, the detection intensity on the left of one block is investigated.
Then, in FIG. 8F, the final detection range DTRG is determined at the place where the detection intensity is the highest.
In other words, the place where the subject OBJ is located at substantially the center of the detection range DTRG is determined as the final detection range DTRG.

After examining the number of blocks of the target frequency in step ST4, the subject position determination unit 17 determines whether or not the number of blocks of the target frequency is greater than 0 (ST5).
If it is determined in step ST5 that the number of blocks of the target frequency is greater than 0, the subject position determination unit 17 stores the detected position information obtained by searching the position storage unit 144 of the light source analysis processing unit 14 (ST6).
Then, the number “No” in the table TBL1 of the position storage unit 144 is incremented by 1 (ST7).
The subject position determination unit 17 designates the next detection range DTRG (x, y) (ST8).
If the subject position determination unit 17 determines in step ST5 that the number of blocks of the target frequency is 0, the process proceeds to step ST8 without performing steps ST6 and ST7.
The subject position determination unit 17 repeats the processes of steps ST5 to ST8 until the detection of the target image is completed (ST9).
In step ST9, when the detection of the target image is completed, areas having numbers consecutive in the (x, y) direction are integrated from the detected position information in the position storage unit 144 (ST10), and the number of detected positions is acquired (ST11). .

If the subject position determination unit 17 determines not to perform the position determination process in step ST1, the subject position determination unit 17 proceeds to the process from step ST12 in FIG.
The subject position determination unit 17 acquires the designated number from the position storage unit 144 (ST12).
Here, the subject position determination unit 17 determines whether or not there is a designated number (ST13).
If it is determined in step ST13 that there is a designated number, the subject position determining unit 17 acquires (x, y) width information of the detection range DTRG in the position storage unit 144 from the designated number (ST14), and the subject in the detection range DTRG is obtained. A state is detected (searched) (ST15).
Then, the number “No” in the table TBL1 of the position storage unit 144 is incremented by 1 (ST16).
The subject position determination unit 17 repeats the processes of steps ST14 to ST16 until the detection of the target image is completed (ST9).
If the subject position determination unit 17 determines that there is no designated number in step ST13, the subject position determination unit 17 detects (searches) the subject state of all pixels without performing the processing of steps ST14 to ST17.

  Next, a process for correcting the detected position information along with the tracking process according to the present embodiment will be described.

As described above, the position search processing unit 171 searches the current position from the detection state obtained by the determination unit 16. At this time, the position search processing unit 171 or the tracking processing unit checks a flag indicating whether the tracking process is necessary, and performs the tracking process when the tracking process is necessary.
The tracking processing unit 173 has a function of monitoring the external timer processing unit 18 and performing a tracking process only when it matches an arbitrary time or a constant interval condition.
As already described, the tracking processing unit 173 basically has a positional shift caused by a long-term secular change or an environmental condition between the position of the subject to be detected and the imaging device. It has a function of correcting the position while correcting the position shift while adjusting the correction state and time according to the elapsed time of the position shift.

The timer processing unit 18 counts (measures time) an arbitrary time or a predetermined interval time, and notifies the subject position determination unit 17 of the information.
Basically, the tracking processing unit 173 performs timer determination and performs tracking processing once when the time condition matches the notification information.
For example, when the time condition is every minute, the tracking processing unit 173 performs the tracking process based on the count per minute notified by the timer processing unit 18.
Further, if the time condition is, for example, 8:20:00 am, tracking processing unit 173 performs tracking processing based on the time notified by timer processing unit 18.

The position search information storage unit 172 has a tracking time table TTRK in which tracking processing information is tabulated, and stores the tracking progress.
The tracking processing unit 173 includes a tracking counter 1731. For example, when the time condition of the tracking process is every minute and there are four tracking time tables TTRK, the table TTRK1 is processed by the first match and the table by the second match. The tracking process is performed according to the procedure of TTRK2, and the tracking counter is set to 0 at the fifth match, and the process from the table TTRK0 is performed again.
The tracking processing unit 173 tracks 4 × 1 minutes with respect to one detection position, and if there are two detection positions, 4 × 1 × 2 minutes are required.
The tracking processing in the tracking processing unit 173 has parameters for the number of tracking time tables, and the x and y axis directions of the tracking range can be set.
When there are four tracking time tables TTRK, the tracking processing unit 173 performs tracking processing at positions near the four directions.

FIG. 9 is a diagram illustrating an example of forming a tracking time table stored in the position search information storage unit.
FIG. 10 is a diagram for explaining the relationship between the subject shift direction and the tracking time table.

9 and 10, “No” indicates the number of the subjects OBJ1 and OBJ2 to be detected. In this example, there are two subjects “No. 1” and “No. 2”.
In this embodiment, as shown in FIG. 9, tracking time tables TTRK1 and TTRK2 are formed corresponding to the subjects OBJ1 and OBJ2. Both tables TTRK1, TTRK2 have the same configuration.
ID0, ID1, ID2, and ID3 indicate positions where the detection range DTRG (1,2) of the subject OBJ (1,2) is shifted in the X direction and the Y direction of the orthogonal coordinates set in FIG.
In the example of FIG. 10, “ID0” indicates the + Y direction, “ID1” indicates the −X direction, “ID2” indicates the −Y direction, and “ID3” indicates the + X direction.
In the tracking time table TTRK, (Xt, Yy) indicates a correction value in each direction ID0, ID1, ID2, ID3.

In the direction ID0, Xt = 0 and Yt = −1 are caused by a positional shift in the direction ID0, and this shift is shifted in the + Y direction from the detection range DTRG. 1 ”means to correct.
In the direction ID1, Xt = 1 and Yt = 0 are caused by a positional shift in the direction ID1, and this shift is shifted in the −X direction from the detection range DTRG. It means to correct it.
The reason why Xt = 0 and Yt = 1 in the direction ID2 is that there is a positional shift in the direction ID2, and this shift is shifted in the −Y direction from the detection range DTRG. It means to correct it.
In the direction ID3, Xt = −1 and Yt = 0, because a positional shift occurs in the direction ID3, and this shift is shifted in the + X direction from the detection range DTRG. 1 ”means to correct.

In the tracking time table TTRK, “Func.No” indicates function numbers f1 to f4 in the directions ID0, ID1, ID2, and ID3.
“Count” indicates the count value of the tracking counter 1731.

The tracking processing in the tracking processing unit 173 includes a pixel value of a luminance signal at a nearby position obtained by correcting the (x, y) coordinates of the position detection memory of the position storage unit 144 with the correction value (Xt, Yt) of the tracking time table, and an arbitrary value. Are compared, and if the pixel value is larger, the tracking counter 1731 is incremented by one.
That is, the tracking processing unit 173 sets the tracking counter 1731 to +1 when f (x + Xt, y + Yt)> S.
The tracking processing unit 173 continues to repeatedly perform the tracking process after that, and when the value of the tracking counter 1731 becomes larger than the result of the comparison with the arbitrary second determination value D, the tracking processing unit 173 determines that the position is shifted to a nearby position. The position storage unit 144 has a function of storing the position.
By comparing with the second determination value D for tracking, noise components can be removed and the tracking position can be stably corrected.

In the example of the tracking time table TTRK1 in FIG. 9, the tracking processing unit 173 increments the tracking counter 1731 by 1 when, for example, f2 (x + Xt, y + Yt)> S in the direction ID2.
The tracking processing unit 173 continues to perform the tracking processing thereafter, and when the value of the tracking counter 1731 becomes larger than the result of comparison with the arbitrary second determination value D, the count value is “55” in the example of FIG. For example, when “determination value D = 60” is exceeded, it is determined that the position shifts to a nearby position, and the position storage unit 144 has a function of storing the position.

  With the above processing, it is possible to measure luminance information stably and stably by correcting the detection position correctly in a long-term secular change with little influence on the fine movement component in a short time.

  Hereinafter, the tracking process of the number No. of the detected position memory of the position storage unit 144 will be described with reference to FIGS. 11, 12, and 13.

  FIG. 11 is a flowchart for explaining basic tracking processing of the number No. of the detected position memory of the position storage unit.

The tracking processing unit 173 acquires No information in the detected position memory of the position storage unit 144 (ST21), and acquires the next timer time (ST22).
Then, the tracking processing unit 173 monitors the timer processing unit 18, and when the timer time that is the tracking condition is reached (ST23), the tracking time table number stored in the position search information storage unit 172 is designated (ST24). .
The tracking processing unit 173 acquires the (x, y) coordinates of the position detection memory of the position storage unit 144 and the correction value (Xt, Yt) of the tracking time table TTRK (ST25).
Then, the tracking processing unit 173 arbitrarily calculates the pixel value of the luminance signal at the nearby position obtained by correcting the (x, y) coordinates of the position detection memory of the position storage unit 144 with the correction value (Xt, Yt) of the tracking time table TTRK. The first determination value S is compared (ST26), and if the pixel value is larger, the tracking counter 1731 is incremented by 1 (ST27).
That is, the tracking processing unit 173 sets the tracking counter 1731 to +1 when f (x + Xt, y + Yt)> S.
The tracking processing unit 173 continues to repeat the tracking process thereafter, and the value of the tracking counter 1731 is compared with an arbitrary second determination value D (ST28), and as a result, the count value becomes larger than the second determination value. In this case, it is determined that the position is shifted to a nearby position, and the position is stored in the position storage unit 144.
That is, the tracking processing unit 173 updates the detected position memory (x, y) coordinates of the position storage unit 144 with the coordinates (x + Xt, y + Yt) (ST29), and clears the value of the tracking counter 1731 to 0 (ST30). .
Next, the tracking time table number is incremented by 1 (ST31), for example, and the next timer time is set (ST32).
However, if it is the last tracking time table number in step ST31, the tracking time table number is set to zero.
By comparing with the second determination value D for tracking, noise components can be removed and the tracking position can be stably corrected.

  As in the tracking process of FIG. 11, even if there is a positional deviation caused by a long-term secular change or an environmental condition between the position of the subject to be detected and the imaging apparatus, the correction of the positional deviation is performed. By correcting the position while adjusting the correction state and time according to the elapsed time of the deviation, it is possible to obtain the effect that the luminance information of the subject can be acquired permanently with high accuracy.

  FIG. 12 is a flowchart for explaining the second tracking process of the number No. of the detected position memory of the position storage unit.

The difference between the second tracking process shown in FIG. 12 and the basic tracking process shown in FIG. 11 is that the time for position correction is set for each subject position range to be detected.
Specifically, by having a memory area for setting the timer matching time for each tracking time table TTRK1A, TTRK2A, the tracking time can be set for each detection position range of the subject.

In the flow process, in step ST32A, the tracking processing unit 173 sets the next timer time from the tracking time table.
Other processes in FIG. 12 are basically the same as those in FIG.

  As in the tracking process of FIG. 12, even when there is a positional deviation caused by a long-term secular change or an environmental condition between the position of the subject to be detected and the imaging apparatus, the correction of the positional deviation is performed. The effect is that the brightness information of the subject can be acquired permanently and accurately in a subject-specific state by correcting the position while adjusting the correction time and the time for each subject detection range according to the elapsed time of the deviation. Is obtained.

  FIG. 13 is a flowchart for explaining the third tracking process of the number No. of the detected position memory of the position storage unit.

  A difference between the third tracking process shown in FIG. 13 and the second tracking process shown in FIG. 12 is that a position deviation frequency determination is added to the tracking position determination of the position correction to enable the position correction. It is to have done.

In the flow process of FIG. 13, steps ST33 and ST34 are added between step ST28 and step ST29 of the flow process of FIG.
In step ST33, when the count exceeds the second determination value D, the sum of the count values of each ID in the tracking time table is acquired.
In step ST <b> 34, when the acquired sum is not less than the third determination value F and not more than the fourth determination value L as the position shift frequency determination value, the detection position memory is updated in step ST <b> 29.

As described above, in the third tracking process, a positional deviation frequency determination value is provided as a tracking determination condition, and the frequency of the positional deviation is measured. If the frequency is larger than the determination value, a function of updating the tracking position is provided. .
In order to determine the frequency, the total number of counts of each ID in the tracking time table TTRK is acquired and compared with the frequency determination value. The tracking position is updated when the frequency judgment condition is met.

As shown in the tracking process of FIG. 13, even if there is a positional deviation caused by a long-term change over time or an environmental condition between the position of the subject to be detected and the imaging apparatus, the correction of the positional deviation is performed. In addition to the elapsed time of the deviation, the position is corrected only when the frequency occurs a plurality of times.
As a result, when the range of light emitted by the light source 11 is larger in the directions indicated by ID0 to ID3 at night or the like than in the daytime or the like, the position is temporarily shifted slightly due to strong winds or vibrations. Even in this case, the luminance information of the subject can be obtained permanently and accurately without affecting the measurement.

Next, other configurations and functions of the detection system according to the present embodiment will be described in detail.
First, the configuration of the CCD of the imaging device 12 according to the present embodiment will be described.

  FIG. 14 is a diagram illustrating an example for explaining the structure of the CCD according to the present embodiment.

14 is an interline transfer, and includes a photodiode PD21, a vertical transfer CCD22, a horizontal transfer CCD23, and an amplifier 24.
The photodiodes PD21 are arranged in a matrix. The photodiodes PD21 arranged in the vertical line direction are connected to a vertical transfer CCD 22 for transferring charges for each column. The end of each vertical transfer CCD 22 is connected to a horizontal transfer CCD 23 that transfers charges to the amplifier. An amplifier 24 is connected to the output side of the horizontal transfer CCD 23.

The video scanning method is interlaced, and one screen is interlaced scanning, and is composed of an odd field and an even field.
First, light enters the photodiode PD21, and charges are accumulated in the photodiode PD21 during the charge accumulation time. During this time, the photodiode PD21 and the vertical transfer CCD 22 are disconnected.
When the charge accumulation time ends, the photodiode PD21 and the vertical transfer CCD 22 are brought into conduction, and the accumulated charge is transferred to the vertical transfer CCD 22. Immediately after this, the photodiode PD21 and the vertical transfer CCD 22 are disconnected, and the next charge accumulation is started in the photodiode PD21. The charges transferred to the vertical transfer CCD 22 are transferred to the horizontal transfer CCD 23 for each horizontal line and input to the amplifier 24.
The frequency until charge is transferred from the vertical transfer CCD 22 to the horizontal transfer CCD 23 for each horizontal line is the horizontal scanning frequency of 15.734 Hz of the CCD 20. When all the charges of the vertical transfer CCD 22 are transferred to the horizontal transfer CCD 23, the vertical transfer CCD 22 and the photodiode PD 21 are again brought into conduction, and the charges of the photodiode PD 21 are transferred to the vertical transfer CCD 22. In the case of a field accumulation CCD, charges are accumulated in the photodiode PD21 by photoelectric conversion, and the transfer frequency until this charge is transferred from the photodiode PD21 to the vertical transfer CCD 22 is 59.94 Hz.

  FIG. 15 is a diagram for explaining a time series of the CCD 20 of FIG.

As shown in FIG. 15, the required time until charge is accumulated in the photodiode PD21 by photoelectric conversion is ΔT1, and the required time until the charge is transferred from the photodiode PD21 to the vertical transfer CCD 22 is ΔT2.
As can be seen from FIG. 15, the light energy incident on the CCD 20 is sampled at the charge accumulation period ΔT = ΔT1 + ΔT2 = (1 / 59.94) seconds while being integrated during the charge accumulation time ΔT1.

As shown in FIG. 1, a luminance signal is extracted by a luminance signal extraction unit 13 from a captured image signal captured by the imaging device 12, and the luminance signal is input to the light source analysis processing unit 14.
Here, a method for reading out pixels from the CCD 20 (see FIG. 14) according to the present embodiment will be described.

FIG. 16 is a diagram showing an arrangement example of pixels of a single-plate complementary color filter type CCD.
FIG. 17 is a diagram illustrating an example of a combination of color signals in the odd field OFD and the even field EFD.

The color filter of the pixel is composed of Ye (yellow), Cy (cyan), Mg (magenta), and G (green), and is arranged as shown in FIG. Pixels are read by adding the upper and lower pixels. The combination to be added is shifted by one column between the odd field OFD and the even field EFD. Specifically, in the n-th line of the odd field OFD, (C11 + C21), (C12 + C22), (C13 + C23), (C14 + C24), (C15 + C25),... In the n-line of the even field EFD, (C21 + C31), (C22 + C32), (C23 + C33), (C24 + C34), (C25 + C35),...
Accordingly, color signals are output in the odd field OFD and the even field EFD as shown in FIG.
In any case, the same color pattern of a combination of Ye, Cy, Mg, and G is repeated in a two-pixel cycle.
In other words, the color signal appears superimposed on a frequency of two pixel periods or more. Therefore, if this color signal is passed through a low-pass filter having a cutoff frequency of two pixel periods, the color signal is lost and only a luminance signal is obtained.
Therefore, luminance information is sampled at a cycle of two pixels.

A projection area REG indicated by a circle in FIG. 16 shows a state in which an image of a subject by a light source is projected. It is assumed that the pixels C35, C36, C45, C46, C55, and C56 are completely in the projection region REG and are uniformly irradiated with light.
In the odd field OFD, the luminance information is read by a combination of C35, C36, C45, and C46 of the horizontal line (n + 1), and in the even field EFD, by a combination of C45, C46, C55, and C56 of the (n + 1) line of the horizontal line. Is done.

  As described above, the luminance signal among the signals from the imaging device 12 is output to the light source analysis processing unit 14. This luminance signal is input to the first calculation unit 141 and the second calculation unit 142 and subjected to predetermined processing.

  Next, a luminance signal processing method performed by the first calculation unit 141 and the second calculation unit 142 will be described with reference to FIG.

  FIG. 18 is a timing chart for explaining the signal processing method of the luminance signal of the light source analysis processing unit according to the present embodiment.

FIG. 18A is a diagram showing interline scanning of the imaging device 12 and shows a state of either the even field EFD or the odd field OFD. FIGS. 18B to 18E respectively show waveforms W1, W2, W3, and W4 representing changes in luminance signal level processed by the light source analysis processing unit 14, and FIG. 18F changes at a constant cycle. It is a figure which shows the waveform W5 of the sine wave to do.
The odd field OFD and even field EFD scan one frame. That is, as shown in FIG. 18A, A and B, C and D are one frame scan.
In the following description, f represents frequency, t represents time, θ represents phase difference, and ω satisfies (ω = 2πf). Note that π is the circumference ratio.

A waveform W1 and a waveform W2 illustrated in FIGS. 18B and 18C are waveforms for deriving a function of a waveform indicated by a waveform W3 and a waveform W4 described later.
A waveform W3 illustrated in FIG. 18D is a time development distribution of a function for obtaining the level difference AC when the luminance level difference between the luminance signal of the A field and the luminance signal of the C field is the level difference AC. Indicates.
A waveform W4 illustrated in FIG. 18E is a function time for obtaining the level difference BD when the difference in luminance level between the luminance signal of the B field and the luminance signal of the D field is the level difference BD. The development distribution is shown.
Waveform W3 is derived from waveform W1 and waveform W2, and is obtained by adding waveform W1 and waveform W2 and dividing by two. Waveform W4 is derived from waveform W1 and waveform W2, and is obtained by subtracting waveform W1 from waveform W2 and dividing it by 2.

At this time, a time average SAC that is a first time average of the level difference AC is calculated by the first calculation unit 141 shown in FIG. In addition, a time average SBD that is a second time average of the level difference BD is calculated by the second calculation unit 142.
Specifically, the time average SAC is calculated from the luminance level difference AC between the A field and the C field by a combination of C35, C36, C45, and C46.
Similarly, the time average SBD is calculated from the level difference BD between the B field and the D field by a combination of C45, C46, C55, and C56.

The calculation method of the time average is described.
The time average SAC of the level difference AC between the A field and the C field is calculated by multiplying the waveform W1 by the waveform W3 shown in FIG.
Similarly, the time average SBD of the level difference BD between the B field and the D field is a waveform representing the time change of light irradiated to the pixel by the combination of C45, C46, C55, and C56, as shown in FIG. The time average SBD is calculated by multiplying the waveform W4 shown.

First, a method for calculating the time average SAC will be specifically described.
The waveform W3 is expressed by a mathematical expression. First, the waveform W1 and the waveform W2 can be expressed by the following Fourier series.

  Here, it is assumed that the waveforms W1 and W2 have the same period f2. From equation (1) and equation (2), waveform W3 can be expressed as equation (4).

  By the way, the waveform W5 having the period f1 shown in FIG. 18F can be represented by a sine wave as shown in equations (5) and (6).

  When the waveform W3 represented by the equation (4) is multiplied by the sine wave W5 represented by the equation (5), the equation (7) is obtained.

Next, the time average of the equation (7) from time 0 to time T is taken. Of the terms shown on the right side of the equation (7), the term including time t is an AC signal, so the time average is zero.
Therefore, only when (ω ₁ − (2n−1) ω ₂ = 0), the constant cos θ ₁ and the constant sin θ ₁ remain, and the time average SAC is expressed by the equation (8).

  In this way, the time average SAC is obtained by the first calculation unit 141. Similarly, the time average SBD is obtained by the second calculation unit 142 and is expressed by equation (9).

Now, the sum of squares (S _AC ² + S _BD ² ) of the time average SAC and SBD expressed by the equations (8) and (9) is expressed by the equation (10).

From this equation (10), when the frequency component (f ₁ = (2n−1) f ₂ ) is included in the light incident on the CCD 20 (see FIG. 19), it is expressed by the equation (10). Waveform components are detected.

Next, frequency components included in the light source 11 will be considered.
FIG. 19 is a diagram illustrating a waveform W <b> 6 for the frequency component included in the light source 11. The light source 11 emits light at the luminance level L1 at the frequency f3 for the time τ.

This waveform W6 is developed into a Fourier series. The waveform W6 is a periodic function of a period (T ₃ = 1 / f ₃ ). When (ω ₃ = 2πf ₃ ), the waveform W6 is represented by a general formula of Fourier series as shown in Expression (11).

The coefficients a ₀ , a _n , and b _{n in the} equation (11) are obtained from the waveform W6 as in the equations (12) to (14).

  Therefore, the Fourier series of the waveform W6 is expressed by equation (15).

Therefore, when the blinking period of the light source 11 is set to four times the field period, that is, when (f ₃ = f ₂ ), the frequency coincides with the odd term from the expressions (7) and (15), and the time average SAC And the sum of the squares of SBD is given by equation (16).

  When the duty ratio of lighting of the light source 11 is D, it is expressed by equation (17).

    Therefore, the square sum SACBD of the time average SAC and SBD expressed by the equation (16) is expressed by the equation (18) when the equation (17) is used.

  By the way, the term (19) on the right side of the following equation (18) converges.

  The term (19) on the right side of the equation (18) takes a value as shown in Table 1 with respect to the duty ratio D. Table 1 is shown below.

  Based on Table 1, when the duty ratio D is taken on the horizontal axis and the square sum SACBD of the time average SAC and SBD is taken on the vertical axis, the relationship between the duty ratio D and the square sum SACBD is as shown in FIG. become.

From FIG. 20, it can be seen that the square sum SACBD is maximized at the duty ratio D = 0.5.
Therefore, the sum of squares SACBD expressed by the equation (18) is expressed by the following equation.

[Equation 15]
S _AC ² + S _BD ² = 0.08333L ₁ ² (20)

  As shown in equation (20), the arithmetic processing unit 143 detects the luminance of the light source 11 (see FIG. 1), and outputs the detection result (square sum SACBD) to the determination unit 16 via the filter processing unit 15. To do. This detection result is used for determining the state of the subject by the determination unit 16.

The light source 11 according to the present embodiment does not depend on a specific light source. Therefore, it is considered whether the luminance can be detected for other light sources.
Incandescent light bulbs and fluorescent lamps that are widely used as light sources are 100 Hz in regions where the power supply frequency is 50 Hz and 120 Hz in regions where 60 Hz. The field frequency of an NTSC television is 59.94 Hz, and the field frequency of a monitor used for a personal computer is 60 Hz or more so as not to flicker.

  The field frequency of the NTSC television is 59.94 Hz, and if the light source is caused to emit light at a quarter period, the frequency f2 of the luminance level difference is as follows.

[Equation 16]
f ₂ = 59.94 / 4 = 14.985 Hz (21)

  From the equations (7) and (15), the signal component is detected when the odd multiple of the frequency f2 matches the integer multiple of the frequency f3 of the light source 11.

  Table 2 is a table of values indicating the relationship between the light emission frequency of different light sources and the frequency in the difference in luminance signal level.

F1 in Table 2 is the frequency of the sine wave of Formula (5), f2 is the frequency shown in Formula (21), and f3 is the frequency of the light source 11, the frequency of illumination in the 50 Hz region, and the illumination in the 60 Hz region, respectively. Frequency, NTSC television field frequency, and monitor field frequency used in personal computers.
According to Table 2, up to m = 30, f3 is 100, 120, 59.94 Hz, and there is nothing that satisfies (n × f ₃ = (2m−1) × f ₂ ).

For example, regarding a monitor of a personal computer, if the field frequency is 60 Hz or more, there is a monitor that is scanned at 74.925 Hz as a possibility that the largest output is detected in the signal processing output of the detection system 10. When
That is, when f ₃ = 74.925 Hz, as shown in Table 2, (5 × f ₂ ), (15 × f ₂ ), (25 × f ₂ ), and (1 × f ₃ ), ( 3 × f ₃ ), (5 × f ₃ ). The signal level detected at this time is expressed by the following equation.

したがって、（２２）式で示される信号レベルは光源１１の１／２５のレベルであり、図１に図示していない信号処理で別に除去できる。

Therefore, the signal level expressed by the equation (22) is 1/25 of that of the light source 11 and can be removed separately by signal processing not shown in FIG.

  As described above, the detection system 10 detects the state of the light source or the subject irradiated on the light source without depending on the light emission frequency of the light source.

  Hereinafter, a series of operations of the detection system according to the present embodiment will be described with reference to FIG.

  FIG. 21 is a flowchart for explaining an outline of a series of operations of the detection system according to the present embodiment.

In the present embodiment, first, the luminance of the light source 11 within the charge accumulation time of the imaging device 12 is changed by 4n times the field period of the imaging device 12 (ST41).
Next, a luminance signal is acquired by the luminance signal extraction unit 13 every n fields in the field unit from the imaging device 12 (ST42), and this luminance signal is output to the first calculation unit 141 and the second calculation unit 142.
The first arithmetic unit 141 obtains the time average SAC of the level difference AC of the luminance signal level in the projection area REG of the mth and (m + 2) th fields. Further, the second arithmetic unit 142 obtains the time average SBD of the level difference BD of the luminance signal level in the projection area REG of the (m + 1) th and (m + 3) th fields (ST43).
These time averages SAC and SBD are output to the arithmetic processing unit 143.
Subsequently, the arithmetic processing unit 143 obtains the square sum SACBD of the time average SAC and SBD (ST44), and outputs the result to the determination unit 16 via the filter processing unit 15.
The determination unit 16 determines the state of the subject according to the value of the square sum SACBD (ST45). The determination result is supplied to the subject position determination unit 17.
The subject position determination unit 17 determines whether or not to determine the subject position (ST46).
Here, when the subject position is determined, the subject position determination unit 17 detects the state of the subject and acquires information about the detection position (ST47), and the detected position information is stored in the position storage unit 144 of the light source analysis processing unit 14. Remembered.
When the subject position is not determined, the subject position determination unit 17 acquires the specified position (specified number) from the position information stored in the position storage unit 144 (ST48), and detects the state of the subject at the specified position. (ST49).
Then, when performing steps ST43 and ST44 in the light source analysis processing unit 14, based on the detection position coordinates stored in the position storage unit 144, one or more images of the detection position range specified by the coordinates are obtained. Analysis (detection) is performed.
By this processing of the light source analysis processing unit 14, the present detection system 10 can detect only the position of the light source or the subject irradiated with the light source, and does not detect the position excluded as the subject. It is effective and can be detected with high accuracy.

Then, the position search processing unit 171 of the subject position determination unit 17 searches the current position from the detection state obtained by the determination unit 16. At that time, the position search processing unit 171 or the tracking processing unit checks a flag indicating whether the tracking process is necessary, and performs the tracking process when the tracking process is necessary (ST50, ST51).
Detailed description of the tracking process is omitted here.

In the arithmetic processing unit 143 according to the present embodiment, the square sum SACBD of the time average SAC and SBD is obtained, and the sum of the time average SAC and SBD (S _AC + S _BD ) is determined by the determination unit 16. It can also be used.

  As described above, according to the present embodiment, the background noise of the captured image can be removed, and the state of the subject irradiated with the light source or the light source can be detected.

According to the detection system according to the present embodiment, in the detection of the light source or the state of the subject irradiated with the light source, detection when there are a plurality of subjects can be performed for each subject, and the subject is tracked and captured. Thus, there is no need to detect the position of an unnecessary object that is not a subject, and the effect of detecting the state of the subject at high speed and with high accuracy can be obtained.
Moreover, since it does not depend on the light source, it does not depend on the specifications of the imaging device, and for example, a generally available camera can be used as the imaging device of the present detection system.

According to the present detection system, even when there is a positional shift that has occurred over time or in an environmental condition between the position of the subject to be detected and the imaging device, By correcting the position while adjusting the correction state and time according to the elapsed time of the deviation, the luminance information of the subject can be acquired permanently with high accuracy.
These processes can be realized by the configuration of both the PC system and the embedded system, and can be adapted according to the application.

  In addition, according to the present detection system, even if there is a positional shift caused by a long-term secular change or an environmental condition between the position of the subject to be detected and the imaging apparatus, the correction of the positional shift is performed. By correcting the position while adjusting the correction state and the time for each detection range of the subject in accordance with the elapsed time of the deviation, the luminance information of the subject can be obtained permanently and accurately in a state specific to the subject.

  Furthermore, according to the present detection system, even when there is a positional deviation caused by long-term secular change or environmental condition between the position of the subject to be detected and the imaging apparatus, the correction of the positional deviation is performed. In addition to the elapsed time of misalignment, by correcting the position only when the frequency occurs a plurality of times, the range of light emitted by the light source 11 is larger than that in the daytime and the like at night and so on at ID0 to ID3. When it spreads in each direction shown, even if a slight positional deviation occurs due to strong winds or vibrations, the luminance information of the subject can be obtained permanently and accurately without affecting the measurement.

Furthermore, this detection system uses a plurality of light sources and can transmit signals to the signal processing unit in parallel.
Alternatively, it is possible to provide a plurality of light source colors and perform wavelength multiplexing transmission of signals.
It is also possible to process the signal by appropriately blinking the light source.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described.

In the second embodiment, the field accumulation / interlace imaging device 12 according to the first embodiment is replaced with a frame accumulation / interlace imaging device. At the same time, the luminance change period of the light source 11 according to the first embodiment is changed from 4n times the field period to 4n times the frame period. Accompanying this change in the change period, the luminance signal acquisition period is changed from every n fields to every 2n fields.
As described above, by changing the luminance change cycle of the light source 11 and the luminance signal acquisition cycle, the same effects as those of the first embodiment can be obtained.
Therefore, according to the present embodiment, the background noise of the captured image can be removed, the state of the light source or the subject irradiated with the light source can be detected, and even when there are a plurality of subjects, detection can be performed for each subject.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described.

In the third embodiment, the field accumulation / interlace scanning imaging device 12 according to the first embodiment is replaced with a frame accumulation / non-interlace scanning imaging device.
As described above, even when a non-interlaced scanning imaging apparatus is used, the same effect as that of the first embodiment can be obtained.
Therefore, according to the present embodiment, the background noise of the captured image can be removed, the state of the light source or the subject irradiated with the light source can be detected, and even when there are a plurality of subjects, detection can be performed for each subject.

Note that the method described above in detail can be formed as a program according to the above-described procedure and executed by a computer such as a CPU.
Further, such a program can be configured to be accessed by a recording medium such as a semiconductor memory, a magnetic disk, an optical disk, a floppy (registered trademark) disk, or the like, and to execute the program by a computer in which the recording medium is set.

  DESCRIPTION OF SYMBOLS 10 ... Detection system, 11 ... Light source, 12 ... Imaging device, 13 ... Luminance signal extraction part, 14 ... Light source analysis process part, 141 ... 1st calculating part (A) , 142... Second calculation unit (B), 143... Calculation processing unit, 144... Position storage unit, 15... Filter processing unit, 16. , 171... Position search processing unit, 172... Position search information storage unit, 173.

Claims (8)

A light source;
An imaging device for imaging the light source or a subject illuminated by the light source;
An analysis processing unit that performs analysis processing on a signal acquired from the imaging device;
A determination unit that detects and determines the state of the light source or subject based on the analysis result of the analysis processing unit;
A position storage unit capable of storing information on positions including detection ranges in images of a plurality of subjects;
From the detection information obtained by the determination unit, the position and size of the subject in all images are searched to determine the position of the subject including the detection range, and the detection information including the detection range related to the subject is acquired, A subject position determination unit capable of storing detection information as information about the position in the position storage unit,
The subject position determination unit
Tracking whether or not a detection position shift has occurred, including a tracking processing function for correcting the position information of the position storage unit while adjusting the correction state and time according to the elapsed time of the position shift,
The analysis processing unit
The signal is acquired from the imaging device every predetermined scanning plane period, a time average of the signal level difference is obtained from a signal level difference of the signal between a plurality of different scanning planes, and further, based on the value of the time average Perform an analysis process to perform a predetermined calculation, and output the calculation result of the analysis process to the determination unit,
A detection system that selectively performs the analysis processing on an image in a detection position range specified in the detection information when the detection information is stored in the position storage unit. The subject position determination unit
Set the position correction time for each subject position to be detected,
The detection system according to claim 1, wherein the position is corrected while adjusting the time for each correction state and the detection range of the subject in accordance with the elapsed time of the positional deviation. The subject position determination unit
As tracking determination conditions, including positional deviation frequency determination,
The detection system according to claim 1, wherein the position is corrected only when the frequency occurs a plurality of times in addition to the elapsed time of the position shift. Has a timer processing unit,
The subject position determination unit
The detection system according to any one of claims 1 to 3, wherein the timer processing unit is monitored and the tracking process is performed at least once when the time condition matches the notification information. The subject position determination unit
A tracking counter, and a tracking time table that tabulates information on tracking processing associated with the direction of deviation for each subject to be detected,
In the tracking process, the pixel value of the luminance signal in the vicinity position obtained by correcting the coordinates stored in the position storage unit with the correction value of the tracking time table is compared with the first determination value S, and the pixel value is larger Let the tracking counter count,
After that, the tracking process is continuously repeated, and when the value of the tracking counter becomes larger than the result of comparison with an arbitrary second determination value, it is determined that the position shifts to a nearby position, and the position storage unit stores the position. The detection system according to claim 4 which memorizes information. The subject position determination unit
Set tracking time information for each tracking time table,
The detection system according to claim 5, wherein a next timer time condition is set from the tracking time table every time the tracking process ends. An imaging step of imaging with an imaging device a light source or a subject illuminated by the light source;
A signal is acquired from the imaging device every predetermined scanning plane period, a time average of the signal level difference is obtained from a signal level difference of the signal between a plurality of different scanning planes, and a predetermined average is obtained based on the time average value. An analysis process step for performing an analysis process for performing an operation;
A determination step of detecting and determining the state of the light source or subject based on the analysis result of the analysis processing step;
From the detection information obtained in the determination step, the position and size of the subject in all images are searched to determine the position of the subject including the detection range, and the detection information including the detection range related to the subject is acquired, Subject position determination step for storing detection information in the position storage unit as information on the position,
In the subject position determining step,
Tracking whether or not a deviation of the detection position has occurred, including a tracking process step of correcting the position information of the position storage unit while adjusting the correction state and time according to the elapsed time of the position deviation,
In the analysis processing step,
A signal processing method of a detection system, comprising: a step of selectively performing the analysis process on an image in a detection position range specified in the detection information when the detection information is stored in the position storage unit. An imaging process in which an imaging device captures an image of a light source or a subject illuminated by the light source;
A signal is acquired every predetermined scanning plane period, a time average of the signal level difference is obtained from a signal level difference of the signal between a plurality of different scanning planes, and a predetermined calculation is performed based on the time average value. Analysis processing,
A determination process for detecting and determining the state of the light source or subject based on the analysis result of the analysis process;
From the detection information obtained in the determination process, the position and size of the subject in all the images are searched to determine the position of the subject including the detection range, and the detection information including the detection range related to the subject is acquired. Subject position determination processing for storing detection information in the position storage unit as information on the position,
In the subject position determination process,
Tracking whether or not a deviation of the detected position has occurred, including a tracking process for correcting the position information of the position storage unit while adjusting the correction state and time according to the elapsed time of the position deviation,
In the above analysis process,
When the detection information is stored in the position storage unit, the signal processing of the detection system including the process of selectively performing the analysis process on the image in the detection position range specified in the detection information is performed on the computer. The program to be executed.

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