JP2012137706A - Image processing method, image processor and underwater inspection device equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method, an image processor and an underwater inspection device equipped with the same processing an image of a camera loaded on a mobile body and focusing on an object using only image information.SOLUTION: The image processing method includes: extracting a focusing object image using first feature amount representing color tone change in an acquired image; determining the focusing using second feature amount representing contrast change in the focusing object image; and adjusting a focal point of imaging means using the determination result. This method can thus automatically focusing on the image using only image information so as to improve the operability of an underwater inspection device.

Description

  The present invention relates to an image processing method for processing an image taken by an underwater camera, an image processing apparatus, and an underwater inspection apparatus equipped with the image processing apparatus, and more particularly, an underwater inspection apparatus for inspecting an inside of a nuclear reactor, a shroud and a pressure in the nuclear reactor. The present invention relates to an image processing method, an image processing apparatus, and an underwater inspection apparatus equipped with the image processing method suitable for use in a swimming type underwater inspection apparatus that visually inspects in-furnace equipment such as a jet pump in addition to containers.

  Regarding a captured image processing of a camera mounted on a conventional moving body, first, a technique for forming an image according to a focused state from contrast information of a subject is known (for example, see Patent Document 1).

  Secondly, a technique for enhancing the contrast of an object and improving the visibility of an object is disclosed (for example, see Patent Document 2).

  On the other hand, a technique for suppressing the shake of an image acquired by an imaging device mounted on an underwater inspection apparatus and improving visibility (see, for example, Patent Document 3).

JP 2000-97637 A JP-A-5-219420 JP 2006-224863 A

  The technique described in Patent Document 1 adjusts the frequency characteristics of an image to form an image in order to satisfy the user's feeling of achieving focus in the focused state. However, since the underwater inspection apparatus which is the subject of the present invention inspects the state of the target portion, it is necessary to focus the target portion regardless of the subjective sense of achievement of the inspector.

  The technique described in Patent Document 2 is intended to enhance contrast, and is performed to enhance an image when copying or printing a photograph. However, the image processing of the present invention is performed for automatic focusing, and the purpose and means are different from the technique for emphasizing the target described in Patent Document 2.

  In addition, the technique described in Patent Document 3 stabilizes image shake of a video photographed by an underwater inspection apparatus. Although it corrects the vertical and horizontal shake of the image, it cannot correct the shake of the focus due to the shake in the front-rear direction.

  In order to solve the above problems, an object of the present invention is to provide an image processing method, an image processing apparatus, and an underwater inspection apparatus equipped with the image processing method that achieve focusing on an object using only image information. is there.

  The present invention extracts a focus target image using a first feature amount representing a color tone change in an acquired image, and determines a focus using a second feature amount representing a contrast change in the focus target image. And the focus of the photographing means is adjusted using the determination result.

  According to the present invention, the image can be automatically focused using only the image information, and the operability of the underwater inspection apparatus is improved.

It is a figure which shows the equipment arrangement | positioning of the underwater inspection apparatus in the underwater inspection work by Example 1 of this invention. It is a figure which shows the structure of the vehicle for an inspection in Example 1 of this invention. It is a figure which shows the focus control mechanism in Example 1 of this invention. It is a figure which shows the processing flow of focus control in Example 1 of this invention. It is a figure which shows the image image before and after implementation of focus control in Example 1 of this invention. It is a figure which shows the example of the image parameter used for focus control in Example 1 of this invention. It is a figure which shows the structure of the underwater camera in Example 2 of this invention.

  Hereinafter, the configuration and operation of an underwater inspection apparatus according to an embodiment of the present invention will be described with reference to FIGS. The underwater inspection apparatus according to the present embodiment is used for defect inspection in a nuclear reactor, particularly for visual inspection of a structure.

First, with reference to FIG. 1, an equipment arrangement during an underwater inspection work using the underwater inspection apparatus according to the present embodiment will be described.
FIG. 1 is an equipment layout diagram for underwater inspection work using an underwater inspection apparatus according to an embodiment of the present invention.

  In the nuclear reactor 1, there are structures such as a shroud 2, an upper lattice plate 3, a core support plate 4, and a shroud support 5. In addition, an operation floor 6 that is a work space is provided in the upper part of the nuclear reactor 1, and a fuel changer 7 is also provided in the upper part.

  The inspection vehicle 8 that has entered the nuclear reactor 1 is connected to the control device 10 via the vehicle cable 9. The control device 10 supplies power for moving the inspection vehicle 8 in the water and navigating it, and performs video communication in order to perform a visual inspection at the inspection target location. Further, a display device 11 is connected to the control device 10 and displays an image from an imaging means mounted on the inspection vehicle 8. Further, a controller 12 is connected to the control device 10 and is operated by a vehicle operator 13a. On the fuel changer 7, the operation assistant 13b runs the vehicle cable 9.

  The control device 10 includes a display for displaying, on the display device 11, a position control means for controlling the movement of the position of the inspection vehicle 8 and an image picked up by the image pickup means mounted on the inspection vehicle 8. Image display processing means for generating an image.

Next, the configuration of the inspection vehicle 8 used in the underwater inspection apparatus according to the present embodiment will be described with reference to FIGS.
FIG. 2 is a bird's-eye view showing the configuration of the inspection vehicle 8 used in the underwater inspection apparatus according to the embodiment of the present invention.

  The inspection vehicle 8 is equipped with a camera unit 20 as an imaging means at the front. The camera unit 20 houses a camera and illumination. The vehicle operator 13a shown in FIG. 1 is configured to be able to operate the movement or the like of the inspection vehicle 8 while confirming the image from the camera unit 20.

  Further, a lifting thruster 21 for moving up and down, a propulsion thruster 22 for moving back and forth, and translational turning thrusters 23a and 23b for moving and turning left and right are mounted. The translation turning thrusters 23a and 23b are rotated in the same direction when moving left and right, and rotated in the opposite direction when turning.

  FIG. 3 is a diagram showing details of the camera unit mounted in the camera unit 20 of FIG. 2 and the configuration of the image processing circuit.

  A lens 31 is attached to the front part of the CCD camera, and the lens 31 is moved by a lens driving motor 32 so as to focus. The lens drive motor 32 is preferably a linear drive ultrasonic motor, but may be any actuator that can be linearly driven. The image captured by the CCD camera 30 is captured by the image capture 33, subjected to image processing by the focus determination circuit 34, determined to be in focus, a command value is given to the motor driver 35, and the lens drive motor 32 is operated.

  Next, the procedure and concept of the image processing method according to the present embodiment will be described with reference to FIGS.

  The procedure of the image processing method will be described with reference to FIG. After starting the processing (step 40), the image is captured by the image capture 33 (step 41). Processing for extracting a target area is performed on the image (step 42). Next, a focus determination signal is extracted for the extracted target area (step 43), and the value is evaluated (step 44). If the value is smaller than the previous focus determination signal, the motor driver is driven ( Step 45) If the value is large, it is determined that the subject is in focus (step 46), and the process is terminated (step 47).

  The target area extraction processing in step 42 is to calculate a first feature amount representing a color tone change in the captured image for the entire image, and to set the area where the change amount exceeds a preset value as the target area. . Here, the first feature amount and the second feature amount will be described with reference to FIGS. 5 and 6. FIG. 5 shows an image of a photographed image. The upper diagram shows a state where the focus is not achieved, and the lower diagram shows a state where the focus is achieved (focused). It is assumed that there is an inspection object 51 that is not in focus in the image 50 that is not in focus. The video line 52 used for focus determination is scanned from the upper part to the lower part of the image. FIG. 6 shows an example of the first feature value and the second feature value of the acquired image. A diagram 60 in FIG. 6 plots values on the video line 52 used for focusing determination with respect to the first feature amount on the video line 52 used for focusing determination in the image 50 not focused in FIG. It is a thing. Examples of the first feature amount include a red signal (R), a green signal (G), a blue signal (B) after RGB conversion, a color difference signal (U or V) after YUV conversion, or a hue after HIS conversion. The signal (H) or any other signal can be applied as long as it has a property representing the color tone change of the image. In the diagram 60, when there is a portion (61) in which the amount of change is equal to or greater than a preset value, it is determined that there is an in-focus object, and focus determination signal extraction processing is performed in step 43 of FIG. A diagram 62 in FIG. 6 plots values on the video line 52 used for focus determination with respect to the second feature amount on the video line 52 used for focus determination in the image 50 not focused in FIG. It is a thing. In the diagram 62, the value (63) at the same point as the portion (61) in which the amount of change in the diagram 60 is equal to or greater than the preset value is evaluated. Since there is no change compared with the other parts of the diagram 62, it is determined that the in-focus state is not achieved. Therefore, the motor driver is driven (step 45), the focus determination signal is extracted again (step 43), and the value is evaluated (step 44). A diagram 64 in FIG. 6 shows a second feature amount on the video line 52 used for focusing determination in the focused image 53 in FIG. In the diagram 64, the second feature amount (65) corresponding to the focused inspection object in FIG. 5 has a large amount of change. In the in-focus determination at step 44, the amount of change in the second feature amount is evaluated, and when it exceeds a preset value, it is determined that the in-focus state has been achieved. The second feature amount is an amount having a property indicating the contrast of a color image, and is a luminance signal (Y) after YUV conversion, a saturation signal (S) or luminance signal (I) after HIS conversion, Alternatively, any other object having the property of representing the contrast and brightness of the image can be applied.

  As described above, according to the present embodiment, the first feature amount representing the color tone change in the acquired image is used to extract the focus target image, and the second feature representing the contrast change in the focus target image. It is possible to focus on the inspection object using only the image information by determining the focus using the amount and adjusting the focus of the imaging unit using the determination result. As a result, focusing on an object in visual inspection can be facilitated. Moreover, it becomes possible to stabilize the focus in the image of the camera mounted in the underwater inspection apparatus, and the inspection efficiency in visual inspection can be improved.

  Next, the configuration and operation of an underwater inspection apparatus according to another embodiment of the present invention will be described with reference to FIG. The arrangement of the equipment during the underwater inspection work using the underwater inspection apparatus according to the present embodiment is as follows. In FIG. 1, an underwater camera 70 is used instead of the inspection vehicle 8, and a holding jig that includes the cable instead of the vehicle cable is used. 71 is different, and other configurations, image processing methods, and display methods are the same. The underwater camera 70 is equipped with a camera unit 72 and lamp units 73 a and 73 b, and the video captured by the camera unit 72 is subjected to image processing in the control device 10 and displayed on the display device 11.

  The present embodiment is intended to achieve the same object as the first embodiment, but the apparatus in which the camera is mounted is different from the electrophoretic inspection vehicle 8, and the shake in the vertical and horizontal directions is small. However, since the distance to the object changes from moment to moment and focusing control is required, focusing control using the flow of FIG. 4 in the present invention is effective.

  As described above, according to the present embodiment, focusing control using only image information can be performed, and the inspection efficiency can be improved even when a fixed imaging apparatus is used.

DESCRIPTION OF SYMBOLS 1 Reactor 2 Shroud 3 Upper lattice plate 4 Core support plate 5 Shroud support 6 Operation floor 7 Fuel change device 8 Vehicle for inspection 9 Vehicle cable 10 Control device 11 Display device 12 Controller 20 Camera unit 21 Lifting thruster 22 Propulsion thruster 23a, 23b Thruster 30 for translational turning CCD camera 31 Lens 32 Lens drive motor 70 Underwater camera 71 Holding jig 72 Camera unit 73a, 73b Lamp unit

Claims (5)

An image processing method for focusing an acquired image taken by an imaging means mounted on a moving body,
Using the first feature amount representing the color tone change in the acquired image, the focus target image is extracted, and using the second feature amount representing the contrast change in the focus target image, the focus determination is performed, An image processing method characterized by adjusting a focus of the imaging means using a determination result. The image processing method according to claim 1,
The first feature amount is an amount having a property indicating a color tone of a color image, and is a red signal (R), a green signal (G), a blue signal (B) after RGB conversion, or a color difference signal after YUV conversion ( U or V), or a hue signal (H) after HIS conversion. The image processing method according to claim 1,
The second feature amount is an amount having a property indicating the contrast of a color image, and is either a luminance signal (Y) after YUV conversion, a saturation signal (S) or luminance signal (I) after HIS conversion. An image processing method characterized in that the amount corresponds to crab. An image display processing device for focusing on an acquired image captured by an imaging unit mounted on a moving body,
Using the first feature amount representing the color change in the acquired image, the focus feature image is extracted using the means for extracting the focus target image and the second feature amount representing the contrast change in the focus target image. An image processing apparatus comprising: an in-focus determination unit to perform; and a focus adjustment unit that adjusts a focus of the imaging unit using a determination result in the in-focus determination unit. An inspection vehicle having a driving mechanism capable of migrating in three dimensions and an imaging means capable of visually recognizing a structure in water, and an image display processing means for displaying the output image by focusing the captured image by the imaging means An underwater inspection device comprising:
The image display processing means uses a first feature amount representing a color tone change in the photographed image to extract a focus target image, and uses a second feature amount representing a contrast change in the focus target image. An underwater inspection apparatus comprising: a focus determination unit that performs focus determination; and a focus adjustment unit that adjusts a focus of the imaging unit using a determination result in the focus determination unit.

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