JPH11205779A - Target detector and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the processing arithmetic time and to improve the precision of target detection at the time of acquiring and tracking a moving target by an image pickup device mounted on a guided missile, etc. SOLUTION: The image pickup device 1 picks up the image of a space region including a target and supplies two time-series pictures for a luminance detector. A luminance detector 3 divides an image-pickup screen into plural regions first to detect the average luminance of each divided region and the whole image-pickup screen and an identifying circuit 4 detects a target position based on these. At this time, a first target acquiring area setting circuit 34 sets a target acquiring setting region 2A' based on a first target position information 4a from the circuit 4 and a second average luminance detecting a circuit 37 supplies a signal limited by the region 2A' for the circuit 4. Consequently, the number of processing data for detecting a target at the circuit 4 is remarkably reduced to speedily and precisely detect the target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target detection device and a detection method suitable for detecting and tracking other aircraft or the like mounted on, for example, a guided missile or military aircraft.

[0002]

2. Description of the Related Art Conventionally, when a guided missile tracks a moving aircraft, an imaging device such as a CCD camera is mounted on the guided missile to obtain a still image of a space area including the target aircraft and obtain a static image. By scanning the entire image in pixel units (scanning), the presence / absence of a moving target and its position have been detected.

In order to capture a target such as an aircraft, for example, an average luminance of a still image obtained by photographing is calculated, the luminance of each pixel in the image is compared, and an image of a target having a large difference from the average luminance level is calculated. By extracting and extracting a target, a target excluding a background such as a cloud or a land from a captured image has been detected.

At this time, in order to improve the processing speed, a processing gate is provided around the target once extracted, and the average luminance limited within the processing gate is obtained to adjust the input signal level to the image processor.

[0005]

As described above, the conventional target detection apparatus processes each still image on a pixel-by-pixel basis,
Because it was intended to extract the image pattern of a target such as an aircraft or a background object, for example, if only the target is present alone in a space area where there is nothing other than the target, compare the difference from the average luminance. Moving targets and the like could be clearly and easily identified and detected.

However, in the captured image, in addition to the target image, there is a confusing luminance image pattern similar to the target, such as an image of land and clouds, and when the image enters the processing gate, the average luminance value is reduced. It was an inappropriate value, and it was not easy to identify only the target among them, accurately exclude it from the background, and quickly detect it.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. First, a target detecting apparatus according to the present invention comprises: an image pickup means for obtaining a first photographed image of a target area; A first area dividing means for subdividing the area of the photographed image, and a first detecting means for detecting a target based on the image feature value of each small area formed by the subdivision of the first area dividing means. Target detecting means, first target capturing area setting means for setting an area including the target detected by the first target detecting means as a first target capturing area, and first target capturing area setting After the first target capturing area is set by the means, an area of the second captured image captured by the imaging means is set to a second corresponding to the first target capturing area.
A second target capture area setting means for setting the target capture area, and a second target capture area setting means for setting the second target capture area.
Second region dividing means for subdividing the target capture region of
A second target detecting unit configured to detect a target based on the image feature value in the second target capturing region subdivided by the second region dividing unit.

Further, in the target detecting method according to the present invention, a first imaging step of obtaining a first captured image of a region to be imaged, and a first subdivision of the captured image obtained in the first imaging step are performed. An area dividing step, a first target detecting step of detecting a target based on the image feature value of each small area formed by subdividing the first area dividing step, and a detection by the first target detecting step A first target capture region setting step of setting a region including the set target therein as a first target capture region, and after the first target capture region setting step, a second captured image of the imaging target region And a second target capture area setting step of setting a second target capture area corresponding to the first target capture area on an image captured by the second image capture step. And set in this second target capture area setting step A second area dividing step of subdividing the obtained second target capturing area, and detecting a target based on image feature values in the second target capturing area subdivided in the second area dividing step. And a second target detecting step.

As described above, the target detection apparatus and the target detection method according to the present invention reduce the amount of processing data by subdividing (blocking) the captured image prior to the target detection. Calculations can be speeded up.

In particular, since a second target capturing area is set for the second captured image and subdivision is performed within the limited area, the amount of processed data can be further reduced. Rapid detection of the target and improvement of the detection rate can be realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a target detecting apparatus according to the present invention will be described below in detail with reference to FIGS.

As shown in FIG. 1, in a target detection apparatus according to an embodiment of the present invention, first, an imaging device 1 such as a CCD camera mounted on a guided missile or the like arbitrarily sets a space area including a moving target 2 to an arbitrary position. It is assumed that images are sequentially taken at intervals of time (t seconds). The digital video signal obtained by the photographing of the imaging device 1 is supplied to a luminance detector 3 for detecting an image feature value. Here, the image feature value indicates a luminance, a luminance average, a luminance variance, a differential value, or the like.
In the embodiment described below, description will be made assuming that the luminance and the average luminance are handled.

The brightness detector 3 is constructed as shown in FIG.
Are stored in the memory 31 and then read out sequentially and supplied to the identification circuit 4 and also supplied to the first average luminance detection circuit 32. .

A first area division setting circuit 33 is connected to the first average luminance calculation circuit 32, and the first area division setting circuit 33 captures an image as shown in FIG. A first divided signal that divides an image into q and p pieces at predetermined intervals in the horizontal axis (x-axis) direction and the vertical axis (y-axis) direction is set in advance.

Therefore, the first average luminance calculating circuit 32
Upon receiving the supply of the q × p first divided signals from the first region division setting circuit 33, the imaging region is divided into q × p sub-divisions (blocks) as shown in FIG. Calculate the average luminance of the entire screen together with the average luminance signal in each subdivision area, and supply them to the first target capture area setting circuit 34 and the identification circuit 4, respectively. Note that the average luminance of the entire screen is calculated based on each average luminance of each subdivision area. Further, the average luminance value can be represented by, for example, 256 gradations of light and shade.

It should be noted that the target image and the images of the clouds and the land are each captured as a pattern composed of a series of divided areas whose average luminance levels are approximately similar to each other. Therefore,
In this embodiment, the identification circuit 4 is different from the conventional pixel unit, and as shown in FIG. 3B, a target 2 area and an area area of each of the backgrounds 2a and 2b are respectively divided into subdivisions. Identify and derive respective position signals.

The position signal 4a of the target 2 out of the output of the discriminating circuit 4 is supplied to the first target capturing area setting circuit 3 of the luminance detector 3.
4 and the first target capture area setting circuit 34
As shown in (b), a first target capture area 2A of a rectangular frame including the target 2 at substantially the center is set, and the target capture area 2A signal is transmitted to the second target capture area as shown in FIG. The average luminance value of each of the subdivided regions in the region 2A together with the target capture region 2A signal is compared with the comparison circuit 3
6 respectively.

Next, after a lapse of time t seconds from the first photographing, the target 2 area is photographed again by the imaging device 1, and the digital video signal is similarly stored in the memory 31 and supplied to the identification circuit 4. At the same time, among the stored digital video signals, as shown in FIG. 4A, digital luminance signals in a spatial region including the moving target 2 are sequentially read, and as shown in FIG.
Is supplied to the second average luminance detection circuit 37 shown in FIG.

The average luminance calculating circuit 37 includes the second
The target capture area setting circuit 35 and the second area division setting circuit 38 are connected, and the second target capture area setting circuit 35 receives the target capture area 2A signal from the first target capture area setting circuit 34, As shown in FIG. 4A, a new second target capturing area 2A ′ corresponding to the target capturing area 2A signal capturing the target 2 at the center of the screen is converted to an average luminance calculating circuit 37.
To supply. Of course, if the target 2 is captured at the center, the first target capture area 2A signal itself may be supplied instead of the second target capture area 2A '.

As shown in FIG. 4A, the second area division setting circuit 38 controls the inside of the second target acquisition area 2A '.
A second divided signal that is divided into n and m signals in the horizontal axis (x-axis) direction and the vertical axis (y-axis) direction is set in advance. In this case, the coarseness of the fine division is made finer than the fineness of the fine division in the first area division setting circuit 33, and the detection accuracy of the position of the target 2 described later or the resolution of the detection is increased. You may do it.

Therefore, the second average luminance detecting circuit 37
Similarly to the first average luminance detection circuit 32, the area 2A ′ including the moving target set by the second target capture area setting circuit 35 is divided into n by the area division signal from the second area division circuit 38. × m subdivisions, and, like the first average luminance detection circuit 32, the average luminance in each of the n × m subdivision areas and the average luminance of the area 2A ′ calculated based on the average luminance Is supplied to the identification circuit 4 via the correction circuit 39, and each average luminance signal in each of the n × m subdivided regions is supplied to the comparison circuit 36 together with its position information.

The discriminating circuit 4, which has received the average luminance signal in each of the n × m subdivided areas and the average luminance signal in the area 2 A ′ via the correction circuit 39, outputs the signal from the first average luminance detecting circuit 32. Processing is performed in the same manner as when a signal is introduced and processing is performed, and the second target capture area setting circuit 35 in the captured image is processed.
The target and the background in the range of the area 2A 'set by the above are identified, the position of the target 2 obtained by the imaging device 1 is detected, and displayed on a display device (not shown).

As described above, according to the present embodiment, the discriminating circuit 4 performs nx ×
Since the calculation is based on the comparison operation of the luminance signals based on the m pieces of limited data, the position detection processing of the target 2 can be speeded up.

In general, as in the prior art, the imaging device 1 is controlled based on the output signal of the identification circuit 4 and is configured to always track the target that the imaging device 1 has captured. If the imaging interval (t seconds) is small even when moving at a high speed, the first target capture area setting circuit 34 or the second target capture area setting circuit 35 also sets the target 2 to each of the areas 2A and 2A '. Is controlled to be located at a substantially central portion of the inside.

However, in tracking a high-speed moving target,
The relative positional relationship between a moving target and its background clouds or land changes relatively quickly. Therefore, after a few steps from the first imaging time shown in FIGS. 3A and 3B, for example, as shown in FIG. 4A and FIG. Since the positional relationship of 2b also changes, FIG.
In the state (b), a part of the background 2a may newly enter the target capturing area 2A 'as shown in an enlarged manner in FIG.

In particular, when the luminance level of the image of the background 2a is close to the luminance level of the image of the target 2, the average luminance in the target capture area 2A 'shown in FIG. Rather than the luminance level of target 2. As described above, since the identification of the target 2 is identified using the average luminance of the area 2A 'as the reference value in the identification circuit 4, the reference luminance level changes, and the identification of the target 2 is clearly detected. It becomes difficult. Therefore, in this embodiment, as shown in FIG. 2, a comparison circuit 36 is provided, and the in-region luminance signal in the region 2A from the first target capture region setting circuit 34 and the second average luminance detection circuit 37 Are compared with the luminance signal in the area 2A ′, and the detected luminance component of the background portion 2a ′ newly entering the area 2A ′ is supplied to the correction circuit 39 as a correction signal.

Accordingly, the correction circuit 39 corrects the level of the average luminance in the area 2A 'from the second average luminance detection circuit 35 based on the correction signal from the comparison circuit 36, so that the background is temporarily stored in the target capture area 2A'. When a part of 2a newly enters and the average luminance level approaches the luminance of the target 2, a decrease in the detection probability of the target 2 is avoided, and an image of the target 2 with high resolution can be captured.

As described above, the comparison circuit 36 and the correction circuit 3
In the configuration of No. 9, the average luminance level approaches the luminance level of the target 2 due to the relative movement of the background, the difference between the average luminance level in the target capture area 2A and the luminance level of the target 2 is reduced, and the target 2 detection probability is reduced. Is prevented from decreasing.

In the above description, the process of calculating the average luminance of each divided area in the first and second average luminance detection circuits 32 and 37 of the luminance detector 3 is a simple addition operation of the digital image signal. Therefore, the processing can be performed in a short time by the high-speed calculation, and the calculation of the average luminance and the setting of the target capture area 35 greatly reduce the data amount in the identification circuit 4, resulting in rapid processing. By the calculation, the position of the target 2 can be detected and tracked in a timely manner.

In the above description of the embodiment, the luminance averaging process performed by the luminance detector 3 and the identification circuit 4 based on the digital video signal from the imaging device 1 is performed by a combination of hardware configurations. As described above, these processing operations can be performed on software of a computer.

As described above, according to the apparatus and method of the present invention, the imaging screen is divided, the target capture area is set, and the image characteristic value such as the average luminance, the luminance variance or the differential value in each divided area is measured. By performing the correspondence comparison on the series, even when the contrast between the target and the background is small or the variance of the luminance of the background or the like is large, the moving target or the like can be accurately detected with good resolution.

[0032]

As described above, the target detecting device and the detecting method according to the present invention can reduce the processing time by a simple structure, and can reliably detect a moving target and the like in a short time. It has a large practical effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a target detection device and a detection method according to the present invention.

FIG. 2 is a configuration diagram showing a luminance detector of the device shown in FIG.

3A is an imaging area set by a first area division setting circuit shown in FIG. 2, and FIG. 3B is set by a first target capture area setting circuit shown in FIG. 2; Area 2A
It is explanatory drawing which shows each imaging area containing.

4 (a) and 4 (b) are explanatory diagrams each showing an image pickup area in the second average luminance detection circuit shown in FIG. 2;

FIG. 5 is an enlarged view of a region 2A ′ shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 imaging device 2 target 3 brightness detector 31 memory 32 first average brightness detection circuit 33 first area division setting circuit 34 first target capture area setting circuit 35 second target capture area setting circuit 36 comparison circuit 37 2 average luminance detection circuit 38 second area division setting circuit 39 correction circuit 4 identification circuit

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[Procedure amendment]

[Submission date] January 14, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (6)

[Claims] 1. An image capturing means for obtaining a first captured image of a target area, a first area dividing means for subdividing an area of the captured image obtained by the image capturing means, and a first area dividing means A first target detecting means for detecting a target based on the image feature value of each small area formed by the subdivision of the first area; and an area including the target detected by the first target detecting means in the first area. A first target capture area setting means for setting as a target capture area; and a second captured image area captured by the imaging means after the first target capture area setting by the first target capture area setting means. A second target capture area setting means for setting a second target capture area corresponding to the first target capture area; and a second target capture area set by the second target capture area setting means. Second area dividing means for subdividing , Target detection apparatus characterized by comprising a second target detection means for detecting a target based on the image characteristic value of the second target acquisition region differentiated subdivision in this second region dividing means. 2. The target detection apparatus according to claim 1, wherein the image feature value includes any one of a luminance, a luminance average, a luminance variance, a differential value, and the like. 3. When a background different from the background in the first target capturing area is detected in the second target capturing area, the second target detecting means is configured to detect a different portion of the background. 3. The method according to claim 1, wherein a target is detected by calculating an image characteristic value.
3. The target detection device according to claim 1. 4. A first imaging step of obtaining a first captured image of an imaging target area, and a first subdivision of the captured image obtained in the first imaging step.
An area dividing step, a first target detecting step of detecting a target based on an image feature value of each small area formed by subdividing the first area dividing step, and a first target detecting step. A first target capture region setting step of setting a region including the detected target therein as a first target capture region; and after the first target capture region setting step, a second imaging of the imaging target region A second image capturing step of obtaining an image, and a second target capturing area setting for setting a second target capturing area corresponding to the first target capturing area on the image captured by the second image capturing step A second area dividing step of subdividing the second target capturing area set in the second target capturing area setting step; and a second area subdividing in the second area dividing step. Based on image feature values in the target capture area Target detection method characterized by comprising a second target detection step of detecting. 5. The target detection method according to claim 4, wherein the image feature value includes any one of a luminance, a luminance average, a luminance variance, a differential value, and the like. 6. The second target detecting step includes, when a background different from the background in the first target capturing area is detected in the second target capturing area, an image of a different portion of the background is detected. The target detection method according to claim 4, wherein the target is detected by correcting the characteristic value.