JPH0781961B2 - Image scratch inspection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image scratch inspection apparatus for inspecting an object to be inspected with a television camera to inspect the presence / absence, position, shape, etc. of a flaw.

[Conventional technology]

FIG. 3 shows a conventional image scratch inspection device of this type. In FIG. 3, (1) is a television camera for picking up an image of an object to be inspected, and (2) is a camera interface for inputting a video signal output from the television camera (1) and converting it into digital multi-valued image data. , (8) is a binarization unit for binarizing multi-valued image data output from the camera interface (2) with a predetermined reference density value to obtain binary image data, (9)
Is a binary image memory for storing the binary image data output from the binarization unit (8), and (10) is a processor equipped with various general-purpose arithmetic processing functions, information storage and input / output functions. is there. The processor (10) performs an analysis process of binary image data stored in the binary image memory (9) and control of each unit.

Next, the operation will be described. The reference density value for binarizing the binarizing unit (8), the so-called binarization level, is the processor (1
0). The multi-valued image data captured by the TV camera (1) and obtained through the camera interface (2) is binarized by the binarization unit (8) into white and black at this binarization level, The value image data is input and stored in the binary image memory. The scratch is detected by analyzing the binary image data with the processor (10).

FIG. 4 is a diagram showing an example of a camera input image of the conventional device and its binary image. In FIG. 4, (a) is a camera input image, which is an image of a long object to be inspected taken in the longitudinal direction above and below the visual field of the camera. In this camera input image (a), the left and right of the image of the inspected part are images of the background part, and have the same density level as the image of the scratch near the center. (E) is a binary image obtained by binarizing the camera input image (a) so that, for example, the scratched portion becomes black, and the background portion becomes black together with the scratched portion. Therefore, in the processing of the processor (10), first, the background portion is removed, and then the flaw detection processing is performed.

[Problems to be Solved by the Invention]

The conventional image flaw inspection device is configured as described above,
When an image of an object to be inspected and a background portion having a density level similar to that of the scratched portion are captured on the same screen, the background portion removal processing is required for the analysis processing of the processor, and it takes a long time to detect the flaw. there were.

The present invention has been made to solve the above problems, and an object thereof is to provide an image flaw inspection apparatus capable of detecting flaws in a short time even if there is an image of the background portion.

[Means for Solving the Problems]

The image flaw inspection apparatus according to the present invention includes a scanning line 1 between the camera interface and the binarization unit having the above-described conventional apparatus.
A line memory for storing the image data of the main line, an image data output from the camera interface, a subtraction unit for obtaining difference data between the image data output from the line memory, and a coefficient for multiplying the difference data A multiplication unit and an addition unit that adds the image data output from the line memory to the multiplication output of this multiplication unit and outputs and stores it in the line memory are provided, and the difference data output from the subtraction unit is supplied to the binarization unit. It is configured in.

[Work]

In the present invention, since the difference data between the image data calculated and stored in the line memory up to the previous scan line and the image data of the current input scan line is binarized, only the portion where the density change in the vertical direction of the screen is binary. Since the image is digitized, it is possible to obtain binary image data with the background part removed.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention.
(2) (9) and (10) are exactly the same as the above conventional device. (3) is a line memory for storing image data for one scanning line, that is, one horizontal line on the screen. (4) is a subtraction unit for obtaining difference data of image data output from both the line memory (3) and the camera interface (2). (5) is a multiplication unit that multiplies the difference data output from the subtraction unit (4) by a coefficient, (6) is a multiplier setting unit that sets and supplies the coefficient to the multiplication unit (5), and (7) is the multiplication unit It is an adder that adds the image data output from the line memory (3) to the multiplication output of (5). The addition output of the addition unit (7) is input and stored in the line memory (3) for calculation of the next scanning line data. (8) is a binarization unit similar to the conventional device,
The difference data output by the subtraction unit (4) is installed at a position where it is binarized.

In the image flaw inspection device configured as described above, the image data obtained for each scanning line in the line memory (3) has the coefficient of the multiplication unit (5) set to a value of 1 or less such as 1/4. By doing so, the difference data in the vertical direction on the screen, that is, the density change amount is added and accumulated little by little, so that it becomes so-called smooth data. FIG. 2 is a diagram showing an example of a camera input image and a binary image in the embodiment of the present invention. In FIG. 2, (a) is the same camera input image as the conventional device, (b) is the density distribution of the input data output from the camera interface (2) of the cross section in the vertical direction of the scratch shown by the broken line, (c) Is the line memory at the same position (3)
The density distribution of the smoothed data accumulated in (1), (d) is the density distribution of the difference data output from the subtraction unit (4) at the same position. The binarization level of the binarization unit (8) is set to a value capable of extracting the scratched portion of the difference data (d). On the other hand, the background part is removed because the density is similar in the vertical direction in the screen and the amplitude of the difference data distribution is very small. (E) is a binary image in which only the scratched portion is extracted.

〔The invention's effect〕

As described above, according to the present invention, the subtraction unit for obtaining the difference data and the line memory are provided, and the multiplication unit and the addition unit store the smoothed image data in the line memory, and the binary data is stored. Since the digitization unit is installed at the position where the difference data is binarized, only the portion where the density change in the vertical direction of the screen, that is, the flaw portion where the background portion is removed can be extracted, and the effect of shortening the flaw detection time can be obtained. is there.

[Brief description of drawings]

FIG. 1 is a diagram of an embodiment of an image flaw inspection apparatus of the present invention, FIG. 2 is a diagram showing an example of a camera input image and a binary image of the apparatus of the present invention, and FIG. 3 is a conventional image flaw inspection apparatus. 4 and FIG. 4 are diagrams showing an example of a camera input image and a binary image of the conventional apparatus. In the figure, (1) is a television camera, (2) is a camera interface, (3) is a line memory, (4) is a subtraction unit, (5) is a multiplication unit, (6) is a multiplier setting unit, ( 7)
Is an addition unit, (8) is a binarization unit, (9) is a binary image memory, (10) is a processor, (a) is a camera input image,
(B) is input data, (c) is smooth data, (d) is difference data, and (e) is a binary image. The same reference numerals in the drawings indicate the same or corresponding parts.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 7/18 W

Claims (1)

[Claims] 1. A television camera for imaging an object to be inspected, a camera interface for converting a video signal output by the television camera into digital multi-valued image data, and image data for one scanning line stored. Line memory,
A subtraction unit for obtaining difference data between the image data output from the camera interface and the image data output from the line memory; a multiplication unit for multiplying the difference data output from the subtraction unit by a coefficient; The multiplier setting unit that sets the multiplier of the multiplication unit, the addition unit that adds the image data output from the line memory to the multiplication output of the multiplication unit and outputs the addition data to the line memory, and the output from the subtraction unit. A binarization unit for binarizing the difference data, a binary image memory for storing the binary image data output from the binarization unit, and an analysis of the binary image data in the binary image memory. And an image flaw inspection apparatus comprising a processor for controlling the above-mentioned respective parts.