JPH1026659A - Judgment apparatus for defective element of image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a judgment apparatus by which whether a target candidate is generated by a defective element or not can be judged surely when the defective element is generated in an image sensor while a target is being searched. SOLUTION: A target-candidate selection part 21 at an image processing part 2 selects a target candidate from the output image of a seeker 1. A flaw judgment part 25 outputs a head-shaking instruction 27 by which the head of the seeker 1 is shaken at the magnitude of a preset range when the target candidate is sent, and it judges a flaw on the basis of whether the position on the image of the target candidate is not changed during its head-shaking operation. The position of the target candidate which is judged to be defective is stored in a flaw coordinate RAM 26, the flaw candidate RAM 26 is referred to when the target candidate exists, and a target candidate in a position other than the position in which the target candidate is judged to be defective is selected. A target/background discrimination part 22 discriminates a target from a background regarding the target candidate which is corrected by the flaw judgment part 25. A tracking processing part 23 outputs a tracking instruction 24 so as to track the discriminated target on the basis of the discriminated result of the target/background discrimination part 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defective element judging device for an image sensor applied to, for example, an infrared image seeker for a flying object.

[0002]

2. Description of the Related Art Conventionally, a flying object infrared image seeker is constructed as shown in FIG. That is, as shown in the figure, the seeker 1 is provided at the head of the flying object, and the image processing unit 2 is provided at the next stage. Seeker 1 above
The gimbal 10 holds a two-dimensional infrared image sensor 11 such as a CCD (Charge Coupled Device), and the sensor output is sent to the defective element data replacement unit 12.
The gimbal 10 is a device for turning the image sensor 11 in an arbitrary direction, and is driven by a tracking command 24 sent from the image processing unit 2. The defective element data replacement section 12 has a defective element registration ROM (Read Only Memory).
y) 13 is connected. All the elements of the image sensor 11 of the seeker 1 are checked before shipment, and the defective elements are selected and registered in the defective element registration ROM 13. The defective element data replacement section 12 responds to the image sensor signal sent from the image sensor 11 by a defective element registration ROM 13.
A defective element is determined based on the registered contents of the above, a process of replacing the signal level of the defective element with the signal level of a normal element around the defective element is performed, and the processed image signal is output to the image processing unit 2.

[0003] The image processing section 2 comprises a target candidate selecting section 2
1, a target / background identification unit 22 and a tracking processing unit 23. The target candidate selection unit 21 selects a target candidate from the image signal sent from the seeker 1. The target / background identification unit 22 identifies whether each target candidate selected by the target candidate selection unit 21 is a target or a background. The tracking processing unit 23 outputs a tracking command 24 to the seeker 1 based on the identification result of the target / background identification unit 22 so as to track the identified target, and controls the position of the gimbal 10.

[0004]

In the two-dimensional image sensor 11, photoelectric conversion elements arranged in a grid form each light receiving visual field through an optical system, and constitute an image as a whole. In this case, in addition to an element without a photoelectric conversion function, that is, a black defect always having a “0” output and a white defect always having a maximum output,
Depending on the operating conditions, the output level is higher /
There are elements that deviate to either low or low, and these are called defective elements. Generally, as described above, a defective element is selected in advance, registered in the defective element registration ROM 13, and the output signal of the defective element is replaced with a signal level of a surrounding normal element, so that image processing is not affected. Like that.

[0005] However, in practice, it is not possible to sort out all the defects before the product is shipped, and a potential defective element may become apparent due to a difference in operating conditions during operation.
If the output signal level of the revealed defective element is higher than that of the surrounding elements, it may be mistaken for the target at the time of capturing the point target. The above point target refers to a case where the target is distant and the apparent size is less than or equal to the visual field of one element. When the defective element is mistaken as the target as described above, FIG.
As shown in (b), the seeker 1 attempts to draw the target (defective element 14) in the seeker image 16 to the image center 15 for tracking, and the error between the image center 15 and the apparent defect direction 19. To drive the gimbal 10 with a tracking command proportional to the angle 17 and shake the head in the direction indicated by the arrow 18,
There is a problem that the error angle 17 does not decrease forever and the seeker 1 shakes off the neck.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when a defective element is generated in an image sensor during a target search, it is ensured that a target candidate is generated by the defective element. It is an object of the present invention to provide a defective element determination device for an image sensor that can determine the defective element.

[0007]

A device for determining a defective element of an image sensor according to the present invention processes an image sensor for searching for a target, a gimbal holding the image sensor, and an output image of the image sensor. Means for selecting a target candidate by selecting a target candidate, and when the target candidate is selected by the target candidate selecting means, means for giving a swing command to the gimbal to cause the image sensor to swing within a preset range, A determination unit that determines whether the position of the target candidate has moved or is at the same position due to the swing of the image sensor, and determines the sensor element at that position as a defective element when the target candidate is at the same position. It is characterized by having done.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a flying object infrared image seeker.

As shown in FIG. 1, a seeker 1 is provided at the head of a flying object, and an image processing unit 2 is provided at the next stage. In the seeker 1, a two-dimensional infrared image sensor 11 such as a CCD is held by a gimbal 10, and the sensor output is sent to a defective element data replacement unit 12. A defective element registration ROM 13 is connected to the defective element data replacement section 12. In the above-mentioned seeker 1, all the elements of the image sensor 11 are checked before shipment, and the defective element is registered as a defective element registration R.
Sorted and registered in OM13. The defective element data replacement section 12 determines a defective element based on the registered contents of the defective element registration ROM 13 with respect to the sensor signal sent from the image sensor 11, and determines the signal level of the defective element in the normal surrounding area. The image signal is replaced with the signal level of the element, and the processed image signal is output to the image processing unit 2.

The image processing unit 2 includes a target candidate selecting unit 2
1, defect determination unit 25, defect coordinate RAM (Random Access)
Memory) 26, target / background identification unit 22 and tracking processing unit 2
3. The target candidate selection unit 21 selects a target candidate from the image signal sent from the seeker 1,
The target candidate is output to the defect determination unit 25. When the target candidate is sent from the target candidate selection unit 21, the defect determination unit 25, for example, moves the seeker's neck around 30 elements or more per round,
A swing command 27 for shaking at a size of about 10% or less of the field of view is output, and a defect is determined based on whether the position of the target candidate on the image does not change during the swing operation. Then, the defect determination unit 25 stores the position of the target candidate determined to be defective in the defect coordinate RAM 26, refers to the defect coordinate RAM 26 when there is a next target candidate, and selects a target candidate other than the position already determined to be defective. Is selected. The defect coordinate RAM 26 is
Initialized when the power of the flying object is turned on.

The target / background identification section 22 includes a defect determination section 25
The target candidate corrected in the step is identified as a target or a background. The tracking processing unit 23 outputs a tracking command 24 to the seeker 1 based on the identification result of the target / background identification unit 22 to drive the gimbal 10 so as to track the identified target.

Next, the operation of the above embodiment will be described with reference to the flowchart shown in FIG. The image data output from the image sensor 11 of the seeker 1 is first input to the defective element data replacement unit 12, and it is checked whether or not it matches the address registered in the defective element registration ROM 13 before shipment of the seeker. Are replaced with data of an adjacent normal element. The data corrected by the defective element data replacement unit 12 is output to the image processing unit 2, and the processing shown in the flowchart of FIG. 2 is executed.

That is, frame processing is started in step A1, and first, original image data is input for each frame (step A2). Then, a spatial filter process is performed on the original image data input for each frame (step A3), and thereafter, a binarization process is performed (step A3). In this binarization process, the level of the input image is compared with a threshold value and converted into binary data of “0” or “1”. Next, the process proceeds to step A5, where it is checked whether the defect determination unit 25 is performing the defect determination process. If the defect determination is not being performed, the target candidate selection unit 21 performs the target candidate selection process (step A6). ). At this time, it is determined whether or not there is a target candidate (step A7).
7 is repeatedly executed.

If it is determined in step A7 that there is a target candidate, the target candidate is determined to have the defect coordinates RA.
The defect determination unit 25 determines whether or not the address matches the address stored in the M26 (step A8). If the address matches, it is determined that the target candidate is due to a defect of the element. Returning, the presence or absence of the next target candidate is determined. If it is determined in step A8 that the target candidate does not match the address in the defect coordinate RAM 26, the defect determination unit 25 sets a determination gate for performing defect determination (step A9). For example, a determination gate of about 5 × 5 elements is set around the position of a target candidate for defect determination.

Next, the swing frame counter is reset (step A10). This swing frame counter
During the swing process, the count is sequentially incremented each time the input image is processed by one frame. After resetting the swing frame counter, the process returns to step A1 to start the next frame processing. In the frame processing at this time,
In step A5, it is determined that the defect is being determined, and the defect determination processing A
Proceed to 11. In the defect determination processing A11, first, it is determined whether or not an element (binary element) which has been set to the high level by the above-described binarization processing exists in the determination gate set in step A9 (step A12). If there is a high-level element, it is determined whether or not the count value of the swing frame counter is equal to or smaller than a specified value, for example, "10" (step A13). A swing command 27 for shaking the seeker's neck with a size of about 10% or less of the field of view with 30 elements or more per round is output to the gimbal 10 (step A14). Thereafter, the process returns to step A1, and the same processing as described above is repeatedly executed. That is, in the defect determination process A11, input image data is examined for about 10 frames, and when the position of the target candidate on the image moves as shown in FIG. Is determined. FIG. 3 shows an image of the target candidate when the seeker is swung.
If the seeker swings as described above, the position moves according to the swing if it is a true target, and if the target is a candidate for a defective element, the position does not move even if the swing is performed, The input image data is examined for about 10 frames while swinging, and it is determined whether the input image data is a true target candidate or a defective element. When the defective element 31 is detected, the address is stored in the defective coordinate RAM 26 (step A15), and the process returns to step A1.

If it is determined in step A12 that there is no high-level element in the determination gate, it means that the target candidate has moved in accordance with the swinging operation. It is determined that there is, and the swing is stopped (step A16).

Then, the high-level element closest to the movement position of the target candidate due to the swing is reset as a target candidate (step A17), and the target candidate is output to the target / background identification unit 22. The target / background identification unit 22 identifies whether the input target candidate is a target or a background (step A18). The tracking processing unit 23 performs a tracking process based on the target identified by the target / background identification unit 22 (Step A19), and outputs a tracking command 24 to the gimbal 10. Hereinafter, tracking processing for the target is executed in the same manner.

[0018]

As described above in detail, according to the present invention, when a target candidate is selected, the seeker's neck is swung by a size within a predetermined range, and during the swing operation, the seeker's neck is displayed on the image of the target candidate. The defect is determined based on whether or not the position of the image sensor does not change, so that the defective element of the image sensor generated during the target search can be reliably determined. It is possible to prevent the player from shaking off and not being able to capture the true target. Also, in the seeker manufacturing stage, even if a defective element occurs in the image sensor, including the system inspection stage in the final form,
The occurrence of the return step can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image sensor defective element determination device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an image processing operation in the embodiment.

FIG. 3 is an exemplary view showing an image when the seeker is swung in the embodiment.

FIG. 4 is a configuration diagram of a conventional infrared image seeker for a flying object.

FIG. 5 is a diagram for explaining a seeker operation when a defective element in a conventional infrared image seeker is erroneously recognized as a target.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Seeker 2 Image processing unit 10 Gimbal 11 Image sensor 12 Defective element data replacement unit 13 Defective element registration ROM 14 Defective element 15 Image center 21 Target candidate selection unit 22 Target / background identification unit 23 Tracking processing unit 24 Tracking command 25 Defect determination unit 26 Defect coordinate RAM 27 Swing command

Claims (1)

[Claims] An image sensor for searching for a target; a gimbal holding the image sensor; target candidate selecting means for processing an output image of the image sensor to select a target candidate; When a target candidate is selected by,
Means for giving a gimbal swing command to the gimbal to swing the image sensor within a preset range; and determining whether the position of the target candidate has moved or is at the same position due to the swing of the image sensor. Determining means for determining a sensor element at that position as a defective element when the candidates are located at the same position;