JPH1021331A - Method and device for reading pattern of examinee - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely read a character impressed on the surface of a steel product and to extract a video removed noise to a minimum by reading a impressed pattern from an image obtained by forming plural images in which a shadow part including plural impressed patterns is expand-processed. SOLUTION: The first image of a camera 4 obtained by the irradiation of light by a first illuminator 6 is inputted by an image input part 21. Then a shadow part expand-processing part 22 expands the impressed part (shadow part) and next, a second image of a camera 4 obtained by the irradiation by a second illuminator 7 is inputted by an image input part 23 and a shadow part expand-processing part 24 expands both impressed parts. Then the respective shadow part extended images by the first and second illuminators 6 and 7 are composed by an image composing part 25 to extract only the places becoming shadow parts to obtain the video of only impressed place removed of the shadow of a scale, etc., stuck to impressing surface. After then a character reading processing part 26 executes character reading and character recognition with respect to the image obtained by extracting only the impressed place.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for reading a pattern of an object to be inspected for reading a pattern such as a character or the like imprinted on a specific surface of the object to be inspected such as a steel material.

[0002]

2. Description of the Related Art To read characters engraved on one surface of an object to be inspected such as a steel material, illumination is applied to the engraved surface of the object to be inspected, and this is imaged by an imaging means such as a TV camera, and this image is taken. Process and read. At this time, reading was realized by applying the fact that the engraved portion becomes a shadow of the character pattern. However, it was necessary to assume that the engraved surface of the object to be inspected was flat and that no foreign matter was attached. For example, Japanese Patent Application Laid-Open No. 48-77730 officially discloses a device related to a character reading device for engraving.

[0003]

However, when reading the actually engraved characters, after the occurrence of rust and the like and the engraving of the characters on the object to be inspected, steel scrap called a scale adheres due to thermal processing or the like. In such a case, there is a problem that shadows other than the engraved characters are generated when the illumination is applied, and the engraved character information cannot be accurately obtained.

[0004] It is an object of the present invention to provide a method and apparatus for accurately reading engraved characters, and another object is to provide a method and apparatus for extracting an image from which noise has been removed as much as possible.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided an imaging method in which light is radiated to a mark pattern surface of an object to be inspected from different directions at different times and provided on a surface perpendicular to the mark pattern surface. The shading portion including the engraved pattern in the two engraved pattern surface images is subjected to dilation processing, and the engraved pattern is read from an image obtained by synthesizing the two dilated processing images. An inspection object pattern reading method is disclosed.

Further, according to the present invention, the first illuminating means for irradiating the pattern surface of the object to be inspected, and the position and direction different from the first illuminating means, can be used at a different time from the first illuminating means. A second illuminating means for irradiating the pattern surface, an imaging means for imaging the two illuminated pattern surfaces by the first and second illuminating means, and two pattern surface images obtained by the imaging means, respectively. Inspection object pattern reading apparatus, comprising: first processing means for performing expansion processing; second processing means for combining two images subjected to expansion processing; and third processing means for reading a pattern from the combined image. Is disclosed.

Further, according to the present invention, the first illuminating means for irradiating the engraved pattern surface of the object to be inspected, and the position and direction of the first illuminating means different from those of the first illuminating means at different points in time. Second illumination means for illuminating the engraved pattern surface of the body;
Imaging means for imaging the two irradiation engraved pattern surfaces by the first and second illuminating means, respectively, and expanding processing of a shaded portion including an engraved part in the two engraved pattern surface images obtained by the imaging means. First processing means, means for performing AND logic between two images subjected to the expansion processing, means for performing pattern reading from an image obtained by the AND logic,
An apparatus for reading a pattern to be inspected, comprising:

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the overall configuration of the engraved character reading device of the present invention. Characters are stamped on a specific surface of a steel material as the test object 1. The test object 1 is transported by the transport device in the direction indicated by the arrow, and the image processing device 5 reads the engraved characters of the test object 1 in the transport process.

[0009] In order to image the engraved surface of the object 1 to be inspected,
The video camera 4 is installed at a position perpendicular to the marking surface and opposed to the center position of the character surface. First and second having the same irradiation angle at positions above and below the engraving plane, which are symmetrical to each other.
Lighting devices 6 and 7 are installed. The installation positions and irradiation angles of the first and second lighting devices 6 and 7 are determined in advance. The sensor 3 detects that the steel material as the inspection object 1 has been transported to the inspection position.
Of the illumination devices 6 and 7 and the input of image pickup of the marking surface by the video camera 4 by the illumination, and control of the start timing of image processing and the like.

The installation positions of the above-mentioned lighting devices 6 and 7 and the video camera 4 are based on the prior application of Japanese Patent Application No. Hei 8 (JP-A-Hei) 8/1992.
It may be determined using, for example, US Pat. Further, if the position control of the lighting devices 6 and 7 and the video camera 4 is always performed according to the Japanese Patent Application No. 8-112498, a correct image can always be obtained even if there is a displacement of the steel material.

The video camera 4 captures an image of an engraved surface by the irradiation light from the first and second illumination devices 6 and 7 as an image by switching. The switching between the first and second lighting devices 6 and 7 is performed at a high speed so that the video camera 4 can sufficiently capture separate images. In addition, steel materials,
There is also a method in which the first and second lighting devices 6 and 7 are switched and the image is taken in a state of being temporarily stopped during the image taking.

The image processing device 5 takes in two images obtained from the video camera 4, performs image processing, and reads and recognizes characters on the marking surface. FIG. 2 shows a character reading processing flow in the image processing apparatus 5. The first image of the camera 4 obtained by the light irradiation of the first lighting device 6 is input by the image input unit 21, the engraved portion (shaded portion) is expanded by the shading portion expansion processing unit 22, and then the second lighting device 7 The second image of the camera 4 obtained by the irradiation of the image is input by the image input unit 23, and the shading part expansion processing unit 2
In step 4, both engraved portions are expanded. The shaded part expanded image by the first lighting device 6 and the shaded portion expanded image by the second lighting device 7 are combined by the image combining processing unit 25 to extract only the shaded portions and adhere to the engraved surface. An image of only the engraved portion from which the shading such as the scale is removed is obtained.
Thereafter, the character reading processor 26 performs character reading and character recognition on the image from which only the engraved portion is extracted.

The above character reading processing flow will be described in detail with reference to FIG. The first illumination input image 32 of the engraved surface 31 obtained by the light irradiation by the first illumination device 6 is obtained as image information in which the engraved character portion 311 and the scale attaching portion 312 are similarly shaded portions. The first illumination input image 32 becomes a first illumination shadow part expanded image 33 in which the shadow part is expanded by the shadow part expansion processing unit 22. Similarly, engraved surface 31
, The second illumination input image 34 is obtained as a shaded image facing the first illumination input image 32 in both the engraved character portion 311 and the scale attachment portion 312. The second illumination input image 34 becomes a second illumination shaded part expanded image 35 obtained by expanding the shadowed part by the shaded part expansion processing unit 24. Each of the shaded part expanded images 33 and 35 extracts only a portion that is a shaded part in both screens in the image synthesis processing unit 25. In other words, the composite image 36 is obtained by executing a process (AND operation of both images) by giving priority to the higher luminance of both images and turning white information except for portions where the black information does not overlap. As a result, even if the scale 312 adheres, it can be removed as image information, so that only the engraved character portion 311 can be extracted.

FIG. 4 shows an example of the arrangement of the lighting devices 6 and 7 and the video camera 4. Camera 4 using steel as inspection object
Is temporarily stopped at the image pickup position, and an image is picked up. The illuminating devices 6 and 7 are arranged at vertically symmetrical positions (positions obliquely L ₁ mm from the character center position), and the irradiation angle is, for example, an angle of 45 ° in the oblique direction. The camera 4 was arranged at a distance of L ₂ mm from the character center position. The camera 4 is movable back and forth, so that the distance between the camera and the steel material is L ₂ mm even if the position of the steel material changes on the steel material transport path. It is preferable to use large lighting devices 6 and 7 so that lighting can be performed correctly even if the steel material moves slightly back and forth. In addition, although the lighting devices 6 and 7 are vertically arranged, there are also examples in which the lighting devices 6 and 7 are installed on the left and right and in which the lighting devices are installed so as to face each other in an oblique direction. The present invention can also be applied to pattern inspection of characters and the like of an inspection object (for example, wood) other than steel.

[0015]

According to the present invention, engraved characters imprinted on a steel material or the like can be accurately read. Furthermore, according to the present invention, the two input by the lighting device from two directions respectively.
After performing shading expansion processing on the two engraved character images,
By combining the images and extracting only the shaded portions of both images and reading the engraved characters, it is possible to extract and read only the engraved characters even if rust etc. occurs or scales adhere to the engraved surface. it can.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall configuration of an engraved character reading device according to the present invention.

FIG. 2 is an overall explanatory diagram showing a flow of a process of reading an engraved character;

FIG. 3 is a partial explanatory diagram illustrating a reading process flow of an engraved character.

FIG. 4 is a diagram showing an example of the arrangement of lighting devices 6 and 7 and a video camera 4;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inspection object 2 transport device 3 sensor 4 video camera 5 image processing device 6 first illumination device 7 second illumination device 21 first illumination image input unit 22 first illumination shadow part expansion processing unit 23 second illumination image input unit 24 Second illumination shading part expansion processing unit 25 Image synthesis processing unit 26 Character reading processing unit 31 Engraving surface 311 Engraving character part 312 Scale attaching part 32 First illumination input image 33 First illumination shadow part expansion image 34 Second illumination input image 35 Second illumination shaded part expanded image 36 Composite image

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiki Umino 3-2-1 Sachimachi, Hitachi City, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (72) Inventor Takayuki Hori 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture ( No address) Inside Kawasaki Steel Corporation

Claims (5)

[Claims] 1. An engraved pattern surface of an object to be inspected is irradiated with light from different directions at different times from each other, and images are respectively taken by imaging means provided on a surface perpendicular to the engraved pattern surface. An inspection object pattern reading method in which a shading portion including an engraved pattern in two captured engraved pattern surface images is subjected to dilation processing, and an engraved pattern is read from an image obtained by combining the two dilated expansion images. 2. A first illumination means for irradiating a pattern surface of an object to be inspected, and a pattern surface of the object to be inspected at a time different from the first illumination means from a position and a direction different from the first illumination means. A second illuminating means, an imaging means for imaging two illumination pattern surfaces by the first and second illuminating means, respectively, and two pattern surface images obtained by the imaging means are respectively taken and expanded. A first processing unit, a second processing unit that combines the two images subjected to the expansion processing,
Third processing means for reading a pattern from the synthesized image;
A device for reading a pattern to be inspected. 3. A first illuminating means for irradiating an engraved pattern surface of an object to be inspected, and an engraving of the object to be inspected at a time different from the first illuminating means from a position and a direction different from the first illuminating means. A second illumination unit for irradiating the pattern surface, an imaging unit for imaging the two irradiation engraved pattern surfaces by the first and second illumination units, respectively, and two of the engraved pattern surface images obtained by the imaging unit. First processing means for expanding a shaded portion including an engraved portion, means for performing AND logic between two images subjected to expansion processing, and means for reading a pattern from an image obtained by the AND logic. A device for reading a pattern to be inspected, comprising: 4. The first and second illuminating means have the same irradiation angle with a position symmetrical with respect to the engraved pattern surface, and the imaging means has a perpendicular to the pattern surface of the object to be inspected. 4. The inspection object pattern reading device according to claim 2, wherein the inspection object pattern reading device is arranged at an arbitrary position along a middle position between the positions of the first and second illumination means. 5. The inspection object pattern reading apparatus according to claim 3, wherein the inspection object is a steel material, and the pattern engraved on the steel material is an engraved character.