JPH01291383A - Image reading method - Google Patents

Abstract

PURPOSE:To perform read, an image processing and an analysis in a short period by reading only an area which goes along a virtual mesh line, and also, in which a crack image part selected and designated manually exists. CONSTITUTION:An optically enlarged projection image of a crack picture image or an image which has been enlarged and displayed by an electronic display means is observed, and by its image, a part in which a crack image A does not exist evidently is selected manually, and read of an area of its part is excluded beforehand. Also, on the crack picture image, a mesh line l is provided virtually, and with respect to only an area going along the virtual mesh line l, what is called 'thinned-out read' is executed. In such a way, the time required for read of a picture image, an image processing and an analysis is shortened, and the probability of mixing of a noise can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image reading method, in particular a method for photographing cracks occurring on the surface of an object such as a concrete structure, and photoelectrically reading the photograph. , In the process of image processing and analysis, a mesh line is created virtually superimposed on the photographic image, and along this mesh line, a portion of the photographic image where a cracked image exists or where a cracked image does not exist is manually identified. The present invention relates to an image reading method for photoelectrically reading a specified area where a cracked image exists.

[Prior art]

Traditionally, cracks that occur on the surface of civil engineering structures such as buildings, bridges, roads, and embankments cause water leakage, which corrodes the steel frames inside these structures and buildings. Accelerates aging.

Particularly recently, when cracks occur in concrete, etc., the exterior material layer applied to the surface of the cracks falls off, resulting in serious accidents, which has become a serious social problem.

Conventionally, the method for inspecting and analyzing cracks that occur on the surface of concrete in these structures and buildings is
For example, apply a crack scale board made of transparent or semi-transparent material with a scale to the cracked area.
In addition to reading the crack width, the workers visually measure by sketching the shape of the crack and converting it into information, and then aggregate and analyze this information data for each virtually set area. The timing of repairs was predicted and determined by predicting the progress of cracks.

[Problem that the invention seeks to solve]

However, measuring cracks visually by workers as described above not only requires a great deal of time and effort and is extremely inefficient, but also reduces measurement accuracy due to individual differences among workers in the measured values. There was a problem. Moreover, there are many different sites where cracks occur, and in some places special scaffolding must be erected to measure cracks, and in some cases it may be necessary to temporarily block traffic. In addition, rain and other factors sometimes made it impossible to carry out measurement work for long periods of time.

In order to solve the above-mentioned problems in workers' visual measurement work, the present inventors first took a photograph of the surface to be analyzed, such as a structure with cracks, at the site, and then used this photographic image to perform photoelectric conversion. We have invented a method for analyzing crack images, which analyzes cracks by obtaining image information and processing and analyzing it. In this analysis method, the entire crack photo image is divided into an area (a small predetermined area) limited by the size of the light-receiving surface of the photoelectric conversion element, the minimum crack width to be analyzed, or the processing capacity of the image processing/analysis device. The cracked photo image is read for each area, analyzed immediately, and the data is accumulated. This reading, analysis, and data accumulation are repeated sequentially. Finally, the accumulated data is synthesized to create an image of the entire cracked photographic image. It is about creating data. In the specific equipment used in this analysis method, the surface size is 1m x 1m.
Take a photo of the surface to be analyzed and the screen size is 50mm x 50m
The micro area is recorded as a photographic image of m.
For example, the size can be set to 0.5 mm x 0.5 mm, so the above-mentioned 50 mm x 50 mm photographic image will be divided into 104 minute areas and read.

However, with commercially available image processing and analysis devices, it takes a relatively long time to read and analyze a single area, so it takes even more time to read and analyze the entire cracked photographic image. Furthermore, when analyzing the entire cracked photographic image, the probability that "noise" will be included increases accordingly.In other words, the wider the area to be read and analyzed, the more likely it is that dirt on the surface to be analyzed or shadows due to surface structure will be misidentified as cracks. The problem was that there were more opportunities to

[Means and operations for solving the problems] The present invention solves the problems in the prior art described above, namely, it takes a long time to read, process and analyze the entire area of a cracked photographic image, and there is also a high probability of noise being mixed in. In view of the increase in the number of cracks, an optically enlarged projected image of a photographic image of cracks or an enlarged image displayed by an electronic display means is observed, and a portion of the image that is obviously clearly cracked and in which no crack image exists is manually selected. In addition to excluding the reading of that area, by creating a virtual mesh line on the cracked photographic image and performing "thinned reading" only on the area along these two virtual mesh lines, reading of the photographic image 1, image The purpose is to significantly shorten the time required for processing and analysis, and to significantly reduce the probability of noise contamination. That is, the present invention divides a photographic image depicting a crack in an object into a plurality of regions, photoelectrically reads the photographic image of each region and converts it into information, and analyzes this information to obtain data regarding the crack. In an image reading method for an analysis process of a cracked photographic image in which data is synthesized to create data regarding cracks in the photographic image, at least one of the position coordinates of a mesh line virtually superimposed on the photographic image is selected. Specify the part where the cracked image does not exist or the part where the cracked image exists from the photographic image that has been enlarged and displayed in advance, input the positional information of the specified part into the computer, and specify The image reading method is characterized in that only the area corresponding to the area excluding the area where the cracked image does not exist or the area corresponding to the area where the cracked image exists is read, and in particular, the enlarged photographic image is read. An image reading method that is an image that is optically enlarged and projected or an image that is enlarged and displayed by an electronic display means, and in the case of the former, an image that is optically enlarged and projected onto an XY digitizer. It is.

The present invention will be explained in detail below.

First, the cracks targeted by the crack photographic image analysis process including the image reading method of the present invention are objects, that is, objects made of concrete, glass, ceramics, plastic, rubber, paint, etc., such as concrete structures, various types of ceramics, Cracks appear on the surface of any object, such as enamel, plastic or rubber molded products of various shapes, refractories, and coatings of various paints. The present invention is to take a picture of a predetermined part of a large object surface including these cracks, for example, by taking a photograph with an optical camera, and to efficiently read the taken photographic image of the crack. That is, the cracked photographic image obtained in this way is virtually divided into a plurality of regions, a mesh line is virtually provided by superimposing the photographic image, and a mesh line is created that includes at least one of the position coordinates of the mesh line. Moreover, a portion where a cracked image does not exist or a portion where a cracked image exists is manually specified from an image that has been optically enlarged and projected or an image that has been enlarged and displayed by an electronic display means, and the specified portion is Location information is input into a computer, and an area on the photo corresponding to the part excluding the part where the cracked image does not exist, or an area on the photo corresponding to the part where the cracked image exists, specified based on the location information. Read only and convert it into information,
This information is analyzed to obtain data regarding cracks, and the data obtained for each image is combined to create data regarding cracks in the object.

The present invention will be described in more detail regarding this process with reference to various drawings showing one embodiment thereof.

FIG. 1 is a bronch diaphragm illustrating the process for imaging cracks and image processing and analysis thereof, including the image reading method of the present invention. This process basically consists of a photography subunit 1 and a cracked photographic image reading/analysis/output subunit 10.

In this embodiment, in the figure, photography subunit 1
The photographic equipment includes, for example, an optical camera and photographic film, a scale for determining the distance between the crack and the optical camera, and lighting equipment. Then, this optical camera photographs a wall surface of 1 m x 1 m including cracks in the concrete wall as one photographic field of view. In this case, the field of view of one photographic image is 50mm x
The image can have a size of 50m or m. Therefore, if the minimum crack width that you want to detect and analyze regarding the cracks on the wall surface is, for example, 0.1 mm, then this 0.1 mm
is 0.005 mm in a photographic image. By the way, 0.
In order to detect and analyze cracks thinner than 1 mm, it is recommended to reduce the size of the field of view taken in one shot.

The reading/analysis/output subunit 10 further includes (
Photo) Image reading device 11, image processing/analysis device 12, C
It consists of a PU (central processing unit) 13 and a display/output device 14, and each device is all controlled by the CPU 13.

FIG. 2 shows a specific example of the photographic image reading device 11 that carries out the image reading process that is the most characteristic feature of the present invention. In the illustrated example, the photo image reading device y1 basically includes a stage 1oo on which a photographed photo is placed, a photo enlarger 101, an XY digitizer 1o2, and the stage 100 arranged in the X-axis motor 103 and Y-axis motor 1o4 to be moved;
It is composed of a microscope @1o5 for observing the photograph on the stage 100 and an imaging device 106 such as a TV camera including an area image sensor for photographing and photoelectrically converting the photographic image.

The operator transfers the cracked photographic image on the stage 100 to the XY digitizer 102 using the photographic enlarger 101.
Enlarge and project on top. FIG. 3 shows a schematic example of an enlarged and projected cracked photographic image, and the enlarged cracked photographic image in the figure shows that the cracked images A are irregularly distributed. In the figure, for convenience of explanation, mensch lines are provided virtually! is shown superimposed on the enlarged crack photographic image. This virtual mesh line 2 is not actually drawn on the cracked photographic image, but a line displaying the virtual mensch line or an image displaying the virtual meshing line is displayed superimposed on the enlarged cracked photographic image. , the mesoche line becomes visible as if it were cracked and drawn on a photographic image. In order to superimpose and display such virtual mesh lines on an enlarged cracked photographic image, the cracked photographic image is transferred to the photographic enlarging device 1.
01, the projected image is optically enlarged and projected onto the xY digitizer 102, and a transparent plastic plate having mesh lines made of an orthogonal lattice, for example, is placed on the projected image.
A mesh line-shaped light emission image consisting of an orthogonal lattice displayed on the RT is projected and superimposed, or a mesh line-shaped light emission image is superimposed on a monitor image of the entire cracked photographic image. The orthogonal grid of mesh lines as described above is square for boat fishing, but may also be rectangular, and the grid spacing on the analysis target surface is, for example, 10 mm, 20 mm, etc.
mm, 30 mm, 50 mm, 100 mm, etc. can be determined as appropriate.

Returning to the image reading process by the photographic image reading device shown in FIG. 2, the operator observes this enlarged projected image together with the virtual mesh lines and then traces the portion of the image that is determined to be a cracked image with a cursor or stylus pen. At this time, if a black-and-white negative film made of fine-grain silver halide is used as the photographic film for photographing the cracks, the cracks will be recorded as a bright elongated linear image standing out against a dark background as a photographic image. Therefore, the operator
For example, it is possible to easily recognize and trace a bright elongated cracked image portion in a cracked photographic image enlarged and projected onto an XY digitizer with a white surface. The XY digitizer 102 converts this traced position into XY coordinate values, and this position information is
It is stored in CPU13.

The operator places the above-mentioned virtual mesh line l drawn on a transparent plastic sheet on the xY digitizer 102 on which the cracked photographic image is enlarged and projected, and while checking the distribution of the cracked image A, converts the sheet into a cracked photographic image. The virtual mesh line 1 is shifted relative to the cursor and fixed at the optimum position for reading the cracked image A, and the position of the virtual mesh line 1 at this time is designated with a cursor. The specified position information is processed in the CPU together with the position information obtained by tracing the crack image that was previously stored in the CPU.
determines the area on the cracked image to be read based on the comprehensive position information.

The CPU 13 controls the X-axis motor 103 and the Y-axis motor 104 based on the positional information of the area to be read, moves the stage 100 appropriately in the X-axis and Y-axis directions, and moves the stage 100 in the photographic image corresponding to the positional information. The micro region is placed at the observation position of the microscope 105 and at the imaging position of the imaging device 106. The arrangement of the area to be read on the photographic image at the observation position and the imaging position may be performed by sequentially following adjacent areas, or may be performed in a random order.

Next, the micro region placed under the objective lens 107 of the microscope 105 is observed by the microscope @ 105 and photoelectrically converted by the imaging device 106 .

Note that the minute area is limited by the size of the area image sensor, the minimum crack width to be analyzed, the processing capacity of the image processing and analysis device, etc. For example, in the case of an area image sensor equivalent to 250,000 pixels, it is 0.5 mm
The size can be set to 0.5 mm. x again
On the Y digitizer, a photographic image is enlarged and projected in one full frame or divided screens. The number of divisions will be determined as appropriate. Then, the offset amount corresponding to the film position of each area when it is divided and enlarged and projected is automatically corrected by the CPU 13 by coordinate calculation.
13 controls the amount of rotation of the X-axis motor 103, the Y-axis motor 104, and the X-axis box 2 motor 108 for long-distance movement in the X-axis direction, so that a predetermined part of the photographic image is placed on the optical axis of the microscope 105. Make it.

If desired, after manually specifying the part where the cracked image exists using the enlarger and the XY digitizer,
When a photographic film holder (not shown) is conveyed under the objective lens of the microscope, a second photographic film holder is provided in a predetermined position on the enlarger, and the second photographic film holder is provided with the object to be analyzed. It is possible to carry out monitoring by visual observation by attaching a copy of a photograph, and enlarging and projecting the area corresponding to the reading area of the microscope and its surrounding area using an enlarger.

As described above, among the regions corresponding to the manually designated portions where the cracked image exists, only the regions along the virtual mesh lines are read by the image reading device 11 for each minute region, and the read information is read by the image reading device 11. is image processed and analyzed by the image processing/analysis device 12 each time,
The analysis data is stored in the CPU 13, and the above process is repeated thereafter.Finally, all the analysis data is totaled by the CPU 13, and displayed and outputted from the display/output device 14 as a crack analysis result. The results of this analysis can be expressed using crack width frequency distribution histograms, crack diagrams, crack angle frequency distribution histograms, etc.

Here, "area corresponding to the part where the manually specified crack image exists" is the positional coordinates of the part where the manually specified crack image exists in the enlarged (projected) crack photo image. This refers to the area that includes the position coordinates on the crack photographic image corresponding to the crack. Furthermore, the term "area along the virtual mesh line" refers to an area that includes the position coordinates on the crack photographic image that correspond to the position coordinates of the virtual mesh line.

As a method to specify the part where the cracked image exists,
In addition to the above-mentioned method of tracing the cracked image, there is also a method of specifying the part where the cracked image exists by surrounding it with a closed curve, or by enclosing the part where the cracked image does not exist with a closed curve and specifying the part where the cracked image does not exist, and then specifying the part where the cracked image does not exist. There are methods such as considering it as a part of the image. These methods are not only applied to the case of superimposing a mesh line provided on a transparent plastic sheet on an enlarged and projected crack photographic image as described above, but also apply to the case where a virtual mesh line on an electronic display is applied to an enlarged and projected crack photographic image. The same applies to the case where line images are optically superimposed, or when a virtual mesh line image is superimposed by the electronic display means on a cracked photographic image enlarged and displayed by the electronic display means.

FIG. 4 is a flow chart showing a specific example of sequence control by the CPU of the crack measuring device. In the figure, the operator first observes a crack image that has been optically enlarged and projected or enlarged and displayed on an electronic display (200), sets a mode for specifying the portion where the crack image exists (201), and then According to the specification mode, the operator manually specifies the part where the crack image that is optically enlarged and projected or the crack image enlarged and displayed on the electronic display exists by tracing with a cursor, etc. 202), and the specified position coordinates are Among the areas on the cracked photographic image corresponding to the included part, the area along the virtually set (203) mesh line is read as a "reading area" (
204) Also, the operator draws a closed curve on the XY digitizer or electronic display using a cursor or the like (202), and draws a virtual area on the crack photographic image corresponding to the part including the position coordinates surrounded by this closed curve. (203) The area along the mesh line is read as the "reading area" (204), or all position coordinates are drawn with a cursor (202) on the cracked photographic image corresponding to the part included in the closed curve. This area is set as an "unnecessary area to read," and all other areas along the virtually set mesh line (203) are read (204).

The image information read in this way is subjected to image processing and analysis by an image processing and analysis device (205).

The analysis results are retrieved from the device by the CPU (206) and are stored as numerical data such as the width, length, position, direction, etc. of the crack. Next, the CPU determines whether there is an unread area within the specified area (207). If there is an unread area, the process returns to step 204 and repeats the process. When the analysis of all reading areas is completed, the data of all reading areas are synthesized and organized (20
8) and the results are displayed on an electronic display (
209) or printed out (210)
.

Note that the operator enlarges and displays only the cracked photographic image without displaying the virtual mesh lines mentioned above, and operates the keyboard connected to the CPU 13 to monitor the screen according to a program in which the spacing and relative position of the virtual mesh lines are entered in advance. Preferred spacing and relative positions can be selected from a menu on the screen, and other values can also be set by direct input.

Incidentally, the image analysis process that is the premise of the image reading method of the present invention is to photoelectrically read a crack image depicting a crack in each minute region and convert it into information, and obtain data regarding the crack from the obtained image information. For example, image processing and analysis for this purpose is performed as follows.

That is, first, an image depicting a crack is photoelectrically read and converted into information for each area, and then image processing is performed on the image information. Among the binary images obtained, a binary image (hereinafter referred to as ' Recognizes the “cracked two-plant image”),
Next, the width, length, and other shapes of the two cracked images are analyzed, and data regarding the cracks is obtained from the results.

Here, recognition of a cracked binary image will be explained. Generally, cracks that occur on the surface of concrete structures have a so-called elongated shape that is longer than their width. In other words, cracks with a certain width, such as 0.1 mm, 0.5 mm, or 0.0 mm, are long and continuous along the surface, and the cracks do not suddenly disappear at a certain point, but usually gradually become thinner. and disappears, and in each case has a certain length. Therefore, in a photographic image of the surface of an object with cracks, a portion corresponding to a crack with a certain width has a corresponding length. Therefore, if an image of the surface of an object is divided into small regions and read, the image of the part corresponding to the crack will always reach the periphery (boundary) of each region. A crack image that does not reach the periphery is too short and narrow in its reading field of view, and cannot be recognized as a crack.

However, if it is necessary to recognize such cracked images, the size of the reading field of view, that is, the size of the area to be divided, can be reduced. As described above, in the present invention, the features of the binary image extracted by image processing, that is, the elongated binary image reaching the periphery of each region are regarded as cracked binary images and are discriminated and recognized.

In addition, when reading an image, the image is read larger than the predetermined size of the area, and at the stage of image analysis, only a predetermined size area is cut out, and the cracked image that exists within it is extracted from this limited area. It is also possible to determine whether the periphery (boundary) has been reached.

Now, although the image reading method of the present invention is used to read a photographic image of a crack that has occurred on the surface of a concrete structure, only the area where the crack exists is subject to image reading. Binary images obtained through image processing, including conversion processing, may include relatively round binary images that correspond to depressions caused by air bubbles generated when concrete is poured. These 2(a images) are mostly scattered and do not reach the periphery of the reading field of view for each area, so they are recognized as cracked and not binary images and are excluded from the analysis. , because binary images such as depressions that reach the periphery of the field of view for each area are small in size or do not satisfy the conditions for being a crack binary image regarding the shape described below, in this case as well, cracks 2 are used. It is recognized that it is not a value image.The conditions for determining and recognizing that this extracted binary image is a cracked binary image are as follows.In other words, the target binary image is Condition 1: The length on the cracked object corresponds to 2.5 mm or more.

Condition 2: The length (L) of the maximum major axis of the binary image is at least twice the interval (W) between its parallel lines (L≧2W).

Condition 3: The value of the formula P2/(4πA) is 3 or more.

(However, if the following three conditions are met: P: its circumference, A: its area, and π: pi), it is determined and recognized that "the binary image is a cracked binary image." . Here, in Condition 2, [Length of maximum major axis of binary image (L)]
" means one extracted binary image (for example, the part of the extracted image that corresponds to the crack is represented by "11 pixels", and the part of the background that does not correspond to the crack image is represented by "〇1 pixels"). It is the maximum length of the straight line connecting one ``11 pixel'' and the other ``11 pixels'' that make up ``P2/( 4π
A)" represents the roundness, and when the extracted image is a perfect circle, the value is 1; when it is not a perfect circle, it is a value greater than 1, and the longer it is, the larger the value is.

However, P in the formula is the number of pixels forming the outer periphery of the "1 pixel" group constituting the extracted image, and A is the total number of pixels in the "1 pixel 1 pixel group constituting the extracted image.

The extracted binary image is a binary image corresponding to a crack on the object, that is, a "crack binary image".

The results obtained by setting various conditions for the binary image extracted for each area of the photographic image and the object as conditions for determining whether the image is cracked or not and recognizing it as a cracked binary image. When comparing the results of visually observing the above crack and measuring its width using a crack scale, it was found that if a binary image that satisfies the above three conditions at the same time is considered a "crack binary image", both results It is preferable that the corresponding f direction is recognized.

Furthermore, in image reading and analysis for each region, "data regarding cracks" is obtained using various characteristic values related to the crack binary image extracted as an image corresponding to the crack through image processing, for example, as follows. It will be done.

(2) Area of crack: Find the pixel number of the "11 pixel" component of the crack binary image, and convert this using the total magnification of photographing, image reading, and image display, etc. to obtain the "area of the crack."

■ Crack length: Perform image processing to thin the cracked binary image to obtain the center line, calculate its length, and convert it using the above total magnification. In other words, the area of the cracked binary image From A and perimeter P, L= (P/2+IT')'4-
The value obtained by adding the above-mentioned total magnification correction to L given by 4A)/2 is defined as the "crack length." In the case of even thinner cracks, the "crack length" can be approximated by adding the above-mentioned total magnification correction to the length of the maximum major axis of the crack binary image.

■Crack width: The quotient of the area of the cracked binary image divided by the length of its center line, or the area A of the cracked binary image
And from the perimeter P, the value obtained by adding the above total magnification correction to W, which is given by W = (P/2-P”/4-4z)/2, is the average value within each area of image reading and analysis. “width of crack”
shall be.

■Crack angle: Find the slope of the straight line connecting both ends of the center line of the crack binary image, or in the case of thin cracks, approximately find the slope of the maximum major axis of the crack binary image, and use this to read and analyze the image. The representative "crack angle" within each area is

■Crack position: The coordinates of the center of gravity of the cracked binary image, or the center point coordinates of the center line of the cracked binary image, or the coordinates of the midpoint of the straight line connecting both ends of the cracked two-level image, and the overall magnification above. The value obtained by adding the correction is defined as the ``crack position'' within each area of image reading and analysis.

The idea behind setting the formulas for the 0 term and 0 term above is as follows. Generally, cracks that appear on the surface of objects are
It is elongated, and naturally the cracked image that captures it and the binary image obtained by image processing it are also elongated. If you divide the screen containing the image into minute areas and look at each area, the sides of the cracked part of the image are almost parallel, and there is no extremely large change in the width. In other words, strictly speaking, the cracked part in the image has straight parts and curved parts, but since the width is relatively uniform, the length of the cracked part can be approximated within this minute area. It can be regarded as a rectangle with the long side being the length and the short side being the width. At this time, this rectangle (
If the area of length and width W) is A and the circumference is P, then L, W
, , the following relationship holds between A and P: (W+L)

Note that when obtaining data regarding cracks from various characteristic values of a crack binary image, it is necessary to consider the total magnification of photographing, image reading, and image display. However, if the system involved in crack analysis is isotropic, the crack angle is not affected by the magnification.

〔Effect of the invention〕

According to the present invention, cracks in an object are photographed and imaged, the crack image on the photograph is divided into a large number of regions, the image is photoelectrically read for each region, converted into information, and this information is analyzed. In the crack photo image analysis process, which involves obtaining data related to cracked images, synthesizing the obtained data, and creating data regarding the entire cracked image, etc., mesh lines with a desired spacing are virtually drawn on the cracked image as desired. Set the relative position and read only the area along this virtual mesh line where the cracked image part that has been manually selected and specified in advance exists (the area where the cracked image part does not exist is not read). Image processing and analysis of a cracked image can be performed in a much shorter time than when reading, image processing, and analyzing the entire area, including areas where no cracks exist. Furthermore, cracks generally occur very locally on the surface of an object, so manually selecting the area where the cracked image part exists can significantly save unnecessary operations, and furthermore, By the selection operation, it is possible to distinguish and exclude defective parts other than cracks, dirt, etc. on the cracked surface to be analyzed, and furthermore, the probability of noise contamination can be significantly reduced. As for the operator's operations, the virtual mesh lines are projected or displayed on a monitor image superimposed on the cracked photographic image, so the operator can know which area of the cracked photographic image is to be read by the image reading device. Important effects can be achieved. Therefore, the present invention is extremely useful in this industry.

[Brief explanation of the drawing]

Fig. 1V is a block diagram showing the basic configuration of an example of a device for carrying out the cracked image analysis process including the image reading method of the present invention, Fig. 2 is a schematic diagram of an image reading device for cracked images, and Fig. 3 is an enlarged diagram. FIG. 4, a schematic diagram showing an example of a crack photograph, is a flowchart of the crack image information analysis process. In the figure, IO is a reading/analysis/output subunit, 11 is a photographic image reading device, 12 is an image processing analysis device, and 13
is the CPU, 14 is the display/output device, 100 is the stage, 1 is the old photo enlarger, 102 is the XY textizer, 103 is the X-axis motor, and 104 is the Y-axis motor.
105 is a microscope, 106 is a 1” V, /J mela,
107 is an objective lens, and 108 is an X-axis box 2 motor. Agent Patent Attorney (8107) Kiyotaka Sasaki (3 others) 3rd
Figure 4

Claims (4)

[Claims] (1) Divide a photographic image depicting a crack in an object into multiple regions, photoelectrically read the photographic image of each region and convert it into information, analyze this information to obtain data regarding the crack, and obtain data. [1] At least one of the position coordinates of a mesh line virtually superimposed on the photographic image; [2] Specify the part where the cracked image does not exist or the part where the cracked image exists from the previously enlarged photographic image, input the positional information of the specified part into the computer, and input the positional information to the computer. 1. An image reading method, comprising: reading only the region corresponding to a portion excluding a portion where the cracked image does not exist, or corresponding to a portion where the cracked image exists, which is specified based on the cracked image. (2) The image reading method according to claim 1, wherein the enlarged and displayed photographic image is an image that is optically enlarged and projected. (3) The image reading method according to claim 1, wherein the enlarged photographic image is an image enlarged and displayed by electronic display means. (4) The image reading method according to claim 2, wherein the enlarged and displayed photographic image is an image that is optically enlarged and projected onto an XY digitizer.