JP2833767B2 - Measurement method of foam volume by image processing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for measuring the volume of bubbles in glass by image processing.

[Conventional technology]

Various glass products are made by molding a molten glass material. For example, transparency such as a front glass of a heater or a viewing window of an industrial furnace is required. Glass products are manufactured with great care so that no bubbles are formed inside during the melting or molding process, but if bubbles are formed inside the product for any reason, defective products This causes problems such as a decrease in production yield and an increase in manufacturing cost. In this way, for the purpose of determining the cause of the occurrence of the foam defect, and correcting the melting conditions and molding conditions based on this, the volume of the bubbles contained in the glass product was measured,
A method is employed in which the size of the bubble is calculated from the measurement result of the volume, and the component of the gas in which the product is enclosed as the bubble is accurately determined by comparing the size of the bubble with the result of gas analysis performed separately.

In the conventional measurement of the foam volume, as shown in FIG.
A sample piece (2) cut to a predetermined size is cut out from a glass product containing the same, a transmitted light is irradiated from a light source (3), and the sample piece (2) positioned and fixed in a petri dish (4) is placed in a stereomicroscope ( While observing in step 5), the major axis (a), minor axis (b) and thickness (c) of the foam (1) are measured with a micrometer (6), and these measured values are measured by a micrometer via a digital meter (7). The volume of the bubble (1) was calculated by inputting it to the computer (8) and performing arithmetic processing.

[Problems to be solved by the invention]

The volume (V) of the foam is obtained by assuming that the foam has an elliptical or elliptical upright surface, and as shown in the following formula, the major axis (a), minor axis (b), and thickness of the foam It was calculated by the ellipse approximation from the measured value (mm) in (c).

However, the shape of the bubble varies in various ways depending on the glass forming conditions, and is often not a true sphere or an ellipsoid. For this reason, when the measurement value of the micrometer (6) is used, it often becomes difficult to accurately calculate the volume (V) of the foam. This, of course, makes it difficult to modify the melting conditions and the molding conditions, adversely affecting the improvement in production yield and the reduction in manufacturing costs.

A main object of the present invention is to provide a highly accurate bubble volume measuring means for integrating and calculating the volume of bubbles in a glass sample piece from a composite projection image of a plane projection image and a front projection image of bubbles using image processing. Is to do.

[Means for solving the problem]

As a means for solving the above-described problems, the present invention is to input a plane projection image and a front projection image of bubbles in a glass sample piece taken by a CCD camera to a display pixel portion of an image processing device, respectively, and to be connected to the image processing device In the storage unit of the microcomputer, the plane projection image and the front projection image of the bubble are stored as a binarized pattern in which the bubble portion is black and the remaining portion is white, and the plane projection image and the front projection image of the bubble are stored. Is transmitted as a plane projection image and a front projection image whose positions on the pixels are corrected to the display pixel unit of the image processing apparatus, and the black pixels of the plane projection image and the front projection image of the corrected bubbles are sent out. The volume of bubbles in the glass sample piece is calculated by integration calculation by the microcomputer.

[Action]

The plane projection image and the front projection image of the bubbles in the glass sample piece are input to a microcomputer with an image processing device and stored as a composite projection image, and then the composite projection image is stored in a display pixel portion of the image processing device. The position is input as a corrected planar projection image and a front projection image, and the number of black pixels is integrated and calculated, thereby calculating the volume of bubbles in the glass sample.

〔Example〕

FIG. 1 is a schematic front view of an apparatus for measuring the volume of a foam used in carrying out the method of the present invention, and FIG. 2 is an explanatory view of a plane projection image, a front projection image and a side projection image of bubbles contained in a glass sample piece. Figure,
FIG. 3 is an explanatory diagram of a method for correcting the size of a bubble, FIG. 4 is an explanatory diagram of a correction state of a pixel position when a composite projection image is produced from a plane projection image and a front projection image of the bubble, and FIG. FIG. 6 is a schematic front view of a display CRT screen for use.

Before measuring the volume of bubbles in a glass sample, a glass sample piece (2) containing bubbles (1) is prepared. The glass sample piece (2) is a bubble-containing glass having a length of 7.5 mm, a width of 7.5 mm, and a thickness of 2.0 mm. As shown in FIG. The installation surface CDGH of the sample piece (2) is polished so as to be parallel to the long diameter ▼. Polishing is performed so that the major axis of the plane projection image of the bubble (1) and the installation surface ABCD of the sample piece (2) are as parallel as possible. However, it is assumed that there is an error represented by the angle θ between the major axis MN of the plane projection image of the bubble (1) and the installation surface ABDC of the sample piece (2).

When the preparation of the glass sample piece (2) is completed, the sample piece (2) is set in the bubble volume measuring device shown in FIG. 1, and a plane projection image and a front projection image of the bubble (1) are taken.

As shown in FIG. 1, the bubble volume measuring device is a stereo microscope (5) connected to a CCD camera (6), a microcomputer with an image processing device (7), a microcomputer display (8), a printer (9). , An image monitor display (10), and an image position adjusting device (11) usually called a mouse.

The input and storage of the plane projection image and the front projection image of the bubble (1) to the microcomputer (7) are executed according to the following conditions. First, the plane projection image of the bubble (1) has its major axis ▲
In order to make the image parallel to the X-axis of the CRT screen of the monitor display (10), the glass sample piece (2) is aligned with the stereomicroscope (5) so that the angle θ becomes zero degree. Shoot. Installation surface CDGH using stereo microscope (5)
The plane projection image of the bubble (1) taken in a state where it is directly opposed to the objective lens is input to the upper part of the CRT screen of the image monitor display (10) as shown in FIG. At the same time, the plane projection image is binarized and stored in the storage unit A (not shown) of the microcomputer with image processing device (7). The major axis of the bubble (1) on the plane projection image is lo. The binarization in the method of the present invention means that the bubble (1) contained in the glass sample piece (2) is a black pixel, and the remaining portion other than the bubble (1) is a white pixel. It means to memorize.

When the input and storage of the plane projection image of the bubble (1) are completed, the input and storage of the front projection image of the bubble (1) are executed according to the following procedure. The installation surface ABCD of the glass sample piece (2) is directly opposed to the objective lens of the stereomicroscope (5), and the major axis is
Is taken parallel to the X axis of the CRT screen of the image monitor display (10), and a front projection image of the bubble (1) is taken. The front projection image of the bubble (1) is input to the lower part of the CRT screen of the image monitor display (10) as shown in FIG. At the same time, the front projection image is binarized and stored in the storage unit B (not shown) of the microcomputer (6) with the image processing device. The long diameter of the bubble (1) on the front projection image ▲
▼ becomes l _1.

Between the major axis l ₁ of the major axis lo and foam on the front projected image of the plane projected on the bubble (1) (1), foam (1) Assuming that it has an elliptical cross section expressed by the following quadratic equation, The following relational expression holds. More specifically, foam (1) In the case of having an elliptical cross section expressed by a quadratic expression, the apparent length of the projected image when the bubble (1) is tilted by an angle θ and viewed from an infinite distance is represented by The intersection N of a tangent line (Y = mX + n) and a straight line (Y = kX) passing through the origin of the coordinate and having an angle θ and orthogonal to the first tangent line, and a second tangent line of the ellipse (Y = mX−n) Of intersection M of a line and a straight line (Y = kX)
Equal to the distance between

Therefore, first, the coordinates (X _n , Y _n ) of the point N are obtained.

mX _n + _n = k _n Then, the coordinates (X _n , Y _n ) of the point N are (−e, −ke). Similarly, the coordinates (X _m , Y _m ) of the point M are (e, ke).

Therefore, the length of ▲ ▼ is According to the definition of the tangent of the ellipse, there is a relationship of n ² = a ² m ² + b ² . The following relational expression holds.

Because k = tanθ When a> b, ▲ ▼ takes the maximum value 2a when θ = O ゜, 180 °, and takes the minimum value when θ = 90 °, 270 °.

Accordingly, the ratio C between the true diameter of the bubble (1) and the apparent diameter of the bubble (1) measured at an angle θ with respect to the X axis is: Will be displayed as

The volume of the bubble (1) in the glass sample piece (2) is calculated by integrating and calculating the number of black pixels of the planar projection image and the front projection image of the binarized bubble (1). In order to facilitate the integration calculation, the plane projection image and the front projection image of the bubble (1) are displayed on the same CRT screen as the image monitor display (10), and the same as the microcomputer (7). It is desirable that the information is stored in the storage unit. Therefore, the storage unit A of the microcomputer (7)
The plane projection image of the bubble (1) stored in the storage unit B is combined with the front projection image of the bubble (1) stored in the storage unit B, and the storage unit A
Is stored as a composite projection image. At the same time, the plane projection image and the front projection image of the binarized bubble (1) are color-coded black or white on all 256 pixels vertically and horizontally on the CRT screen of the image monitor display (10). Is displayed as the synthesized projected image. The synthesis of the projected image in the present invention means the correction of the image. Specifically, the pixels at the same position on the plane projection image and the front projection image of the bubble (1) are compared with each other as follows. Means image processing. That is, the bubble (1) is displayed with black pixels,
Assuming that the remaining portion other than the bubble (1) is displayed by white pixels, the composite projected image of the bubble (1) is color-coded as shown in Table 1 below.

The purpose of the image processing (pixel correction) is as follows.

First, if the plane projection image and the front projection image of the bubble (1) after binarization are combined as they are, if dust having a size enough to deform the bubble image of the original image exists, accurate It becomes difficult to store the projected image of the bubble (1). In such a case, the original image of the portion corresponding to dust is corrected before storing it as a composite projection image, and unnecessary portions are deleted.

Second, if the outline of the planar projection image or the front projection image of the binarized bubble (1) is broken, accurate recognition of the bubble (1) becomes impossible. In such a case, the outline of the disappearing bubble (1) is redrawn. The redrawing of the outline may be performed before storing the composite projection image of the bubble (1) in the storage unit A, or may be performed after storing the composite projection image.

Third, since the transmitted light projected from the light source (3) is used for inputting the plane projection image and the front projection image to the display pixel unit of the image processing apparatus, the inside of the bubble image is brighter than the outline. May be visible. In such a case, the central portion of the planar projection image or the front projection image of the binarized bubble (1) becomes white. Since the basic data for calculating the volume of the bubble (1) is the number of black pixels in the composite projection image, all portions corresponding to the bubble (1) need to be replaced with black pixels. For the replacement operation with black pixels called “fill-in”, a composite projection image of the plane projection image and the front projection image is stored in the storage unit A of the microcomputer (7), and then the volume calculation of the bubble (1) is performed. Running just before.

Through the above image processing, all 256 × 256 pixels were color-coded into black or white on the CRT screen of the image monitor display (10). The volume of the bubble (1) is calculated by integrating the number of black pixels corresponding to the bubble (1) using a microcomputer (7) with an image processing device. The following operations are all related to the calculation of the number of black pixels. First, as shown in FIG. 4, a pixel where a black pixel exists is searched for from the left side in the X-axis direction of the plane projection image. If black pixels are found, CRT screen (10)
Is counted along the Y-axis direction of the bubble (1), and the number of black pixels inside the contour of the bubble (1) is counted.
Is stored as P1 in the _first position of the storage unit. Turning now to the right of the X-axis direction, counting the number of black pixels in the same procedure, stored as P ₂ next to the P _1. Perform this operation on the CRT
This operation is repeated until there are no more black pixels along the X-axis direction of the screen.
As a result, P ₁ , P ₂ … P along the X-axis direction of the CRT screen (10)
Volume calculation data having _n and P _n pixels is arranged. The same operation as described above is executed for the front projection image on the CRT screen (10). Consequently, along the X-axis direction of the CRT screen _{(10), Q 1, Q} 2 ... Q m, a volume calculation data having a number of m pixels in Q _m are aligned.

However, since the plane projection image of the bubble (1) is input in a state of being inclined by an angle θ with respect to the ground plane ABCD as shown in FIG. 2, lo ≧ l ₁ , that is, n ≧ m. . Unless this error 34 is corrected, accurate volume calculation of the bubble (1) cannot be performed. Therefore, it is necessary to re-store the storage position of the front projection image of the bubble (1) from m to n. As a means for correcting this storage position, as shown in Table 2 below, each pixel position of the front projection image aligned along the X-axis direction on the CRT screen (10) is multiplied by the correction factor n / m to obtain a black color. Correct the position and number of pixels.

In this manner, black pixels Q ′ ₁ , Q ′ ₂ ,.
_{... Q 'n-2, Q} ' n-1, Q 'n are stored. Finally, the volume of the foam (1) is calculated. The volume V of the bubble (1) is obtained by multiplying the number of black pixels on the corresponding pixel positions of the plane projection image of the bubble (1) and the corrected front projection image and adding the products. However, in this method, since the volume of the bubble (1) is calculated as the integral value of the rectangular pixel, an elliptic approximation correction coefficient is multiplied as shown in the following equation in order to reduce the error.

Since the volume V of the bubble (1) calculated as follows is calculated as the volume of several black pixels, the volume V of the bubble (1)
_To convert to _R (nl), multiply by a coefficient k as shown in the following equation. That is, the true volume V _R of foam (1) is, V _R = KV - is calculated at the (nl) units.

〔The invention's effect〕

By employing the method of the present invention, the volume of bubbles formed inside the glass can be accurately and quickly measured. Therefore, it is easy to determine the components of the gas enclosed in the product as bubbles by comparing with the results of the gas analysis performed separately, and a great effect is exerted on the retrospective investigation of the cause of defective products.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an apparatus for measuring the volume of a foam used in carrying out the method of the present invention, and FIG. 2 is an explanatory view of a plane projection image, a front projection image and a side projection image of bubbles contained in a glass sample piece. FIG. 3 is a view for explaining a method of correcting the size of a bubble, FIG. 4 is a view for explaining a correction state of a pixel position when a composite projection image is produced from a plane projection image and a front projection image of the bubble, and FIG. FIG. 4 is a schematic front view of a monitor display CRT screen. FIG. 6 is a schematic front view of a conventional bubble volume measuring device. (1) air bubbles, (2) glass sample pieces, (5) stereo microscope, (6) CCD camera, (7) microcomputer with image processing device, (10) images CRT screen of monitor display.

Claims (1)

(57) [Claims] 1. A plane projection image and a front projection image of bubbles in a glass sample piece taken by a CCD camera are input to a display pixel section of an image processing device, and a microcomputer connected to the image processing device. In the storage unit, the plane projection image and the front projection image of the bubble are stored as a binarized pattern in which the bubble portion is black and the remaining portion is white, and a composite projection image of the plane projection image and the front projection image of the bubble is stored. The position on the pixel is sent to the display pixel unit of the image processing device as a corrected plane projection image and front projection image, and the corrected black and white pixels of the plane projection image and front projection image are integrated by the microcomputer. A method for measuring the volume of bubbles by image processing, comprising calculating the volume of bubbles in a glass sample piece.