CN102937592B - Ceramic radome pore and material loosening defect automatic detection method - Google Patents

Abstract

The invention relates to a ceramic radome pore and material loosening defect automatic detection method. The method is characterized in that the detection is carried out with a transmission image processing method. The method comprises the specific steps that: (1) a radome standard grey scale value is obtained; (2) transmission images of different positions of the ceramic radome are obtained; (3) defect area boundary extraction processing is carried out; and (4) a mean gray value and an area of a defect area are calculated; the obtained defect area mean gray value is compared with a mean gray value of the entire image, such that the material loosening state of the defect area can be determined; and the quality of the ceramic radome can be determined with the cooperation of the area value of the defect area. According to the invention, with the image processing automatic detection method, ceramic radome pore and material loosening defect is detected. The detection result is more precise and objective.

Description

Ceramic radome pore and material rarefaction defect automatic testing method

Technical field

The present invention relates to a kind of ceramic radome pore and material rarefaction defect automatic testing method, belong to technical field of nondestructive testing.

Background technology

After thin-walled ceramic radome production, inevitably there is pore and material rarefaction defect, but in current thin-walled ceramic radome product detects, detection to pore and material rarefaction defect is measured by manual observation, the result that this measuring method obtains is extremely inaccurate, cannot guarantee the detection quality of product.

Summary of the invention

The object of this invention is to provide a kind ofly can overcome above-mentioned defect, detect accurately, ceramic radome pore and material rarefaction defect automatic testing method that efficiency is high.Its technical scheme is:

Ceramic radome pore and a material rarefaction defect automatic testing method, is characterized in that adopting following steps: 1) antenna house standard grayscale value obtains; 2) ceramic radome transmission image obtains; 3) defect area Boundary Extraction is processed; 4) calculate the area of defect area average gray and defect area, the defect area gray-scale value and the entire image average gray that obtain compare, for judging the loose situation of material of defect area, the size of the area value in binding deficient district, judges the quality of ceramic radome.

Described ceramic radome pore and material rarefaction defect automatic testing method, in step 1), in ceramic radome inside, light source is set, at the outside ccd video camera that adopts of ceramic radome, automatically carry out image acquisition, obtain the gray scale transmission image of ceramic radome different parts, several gray level images of continuous acquisition different parts, every width image is carried out to gray-scale statistical, calculate total gray-scale value of all images, add up the pixel value of every width image, calculate the total pixel number of all images, by total gray-scale value, divided by total pixel number, obtained the average gray value of all images, as antenna house standard grayscale value.

Described ceramic radome pore and material rarefaction defect automatic testing method, step 2) in, in ceramic radome inside, light source is set, adopts ccd video camera, in antenna house outside, the whole different parts of antenna house is carried out to image acquisition, obtain antenna house different parts gray scale transmission image.

Described ceramic radome pore and material rarefaction defect automatic testing method, in step 3), for pore and material rarefaction defect district are carried out to area statistics, need to first obtain the border of defect area, so carrying out border proposes to process, on gray level image, the gray scale of defect area and background area has larger difference, the border of defect area is the discontinuous result of the gray-scale value of pixel, so can be detected by the mode of differentiate, adopt Laplace operator to process, to a continuous function f (x, y), it is at position (x, y) Laplce's value of locating (being second derivative) is defined as:

${\mathrm{\Δ}}^{2}f=\frac{{\∂}^{2}f}{{\∂x}^2}+\frac{{\∂}^{2}f}{{\∂y}^2}$

In digital picture, by difference, be similar to, its expression is:

Δ ²f＝f(m+1,n)+f(m-1,n)+f(m,n+1)+f(m,n-1)-4f(m,n)

Its template is:

$\left[\begin{array}{ccc}0& 1& 0\\ 1& -4& 1\\ 0& 1& 0\end{array}\right]$

The all coefficient sums of template are 0, that is, if the value of template each corresponding position f (m, n) identical (there is no border), the response of operator is 0.

Described ceramic radome pore and material rarefaction defect automatic testing method, in step 4), after obtaining border, defect area, statistics obtains gray-scale value sum and the total pixel number of each defect area pixel, then by gray-scale value sum respectively divided by total pixel number, obtain the average gray of defect area, the total pixel number of each defect area being obtained by statistics obtains the area of defect area, and the average gray of defect area is made as T ₂, the average gray of the entire image of calculating in step 1) is made as T ₁, the computing formula of the loose rate δ of material is as follows:

$\mathrm{\δ}=\frac{T_2-T_1}{T_1}\×100\%$

By the area value of the loose rate δ of material and defect, judged the quality of ceramic radome.

Compared with prior art, its advantage is in the present invention: adopted image to process automatic testing method to the pore of ceramic radome and material is loose detects, measurement result is more accurate, objective.

Embodiment

A ceramic radome to be detected is carried out to pore and the detection of material rarefaction defect, in ceramic radome inside, light source is set, at the outside ccd video camera that adopts of ceramic radome, automatically carry out image acquisition, obtain the gray scale transmission image of ceramic radome different parts, several gray level images of continuous acquisition different parts, every width image is carried out to gray-scale statistical, calculate total gray-scale value of all images, add up the pixel value of every width image, calculate the total pixel number of all images, by total gray-scale value, divided by total pixel number, obtained the average gray value of all images, as antenna house standard grayscale value, here 20 width images have been gathered, the antenna house standard grayscale value calculating: T ₁=80.

In ceramic radome inside, light source is set, adopts ccd video camera, in antenna house outside, the whole different parts of antenna house is carried out to image acquisition, obtain antenna house different parts gray scale transmission image, then pass through successively following image processing step:

Step 1): after collecting gray level image, for pore and material rarefaction defect district are carried out to area statistics, need to first obtain the border of defect area, so carrying out border proposes to process, on gray level image, the gray scale of defect area and background area has larger difference, the border of defect area is the discontinuous result of the gray-scale value of pixel, so can be detected by the mode of differentiate, adopt Laplace operator to process, to a continuous function f (x, y), Laplce's value (being second derivative) that it is located at position (x, y) is defined as:

${\mathrm{\Δ}}^{2}f=\frac{{\∂}^{2}f}{{\∂x}^2}+\frac{{\∂}^{2}f}{{\∂y}^2}$

In digital picture, by difference, be similar to, its expression is:

Δ ²f＝f(m+1,n)+f(m-1,n)+f(m,n+1)+f(m,n-1)-4f(m,n)

Its template is:

$\left[\begin{array}{ccc}0& 1& 0\\ 1& -4& 1\\ 0& 1& 0\end{array}\right]$

Note, all coefficient sums of template are 0, that is, if the value of template each corresponding position f (m, n) identical (there is no border), the response of operator is 0.

Step 2): after obtaining border, defect area, statistics obtains gray-scale value sum and the total pixel number of defect area pixel, and then the gray-scale value sum of defect area pixel is divided by total pixel number, and obtaining average gray is T ₂=140, the pixel count being obtained by statistics obtains the area of each defect area, and area is S=28mm ², the computing formula of the loose rate δ of material is as follows:

$\mathrm{\δ}=\frac{140-80}{80}\×100\%=75\%$

By the area value S of the loose rate δ of material and defect, judged the quality of ceramic radome.

Claims (5)

1. ceramic radome pore and a material rarefaction defect automatic testing method, is characterized in that adopting image processing method to detect, and concrete steps are: 1) antenna house standard grayscale value obtains; 2) ceramic radome different parts transmission image obtains; 3) defect area Boundary Extraction is processed; 4) calculate the area of defect area average gray and defect area, the defect area gray-scale value and the entire image average gray that obtain compare, for judging pore and the loose situation of material of defect area, the area value in binding deficient district is big or small, judges the quality of ceramic radome.

2. ceramic radome pore as claimed in claim 1 and material rarefaction defect automatic testing method, it is characterized in that: in step 1), in ceramic radome inside, light source is set, at the outside ccd video camera that adopts of ceramic radome, automatically carry out image acquisition, obtain the gray scale transmission image of ceramic radome different parts, several gray level images of continuous acquisition different parts, every width image is carried out to gray-scale statistical, calculate total gray-scale value of all images, add up the pixel value of every width image, calculate the total pixel number of all images, by total gray-scale value, divided by total pixel number, obtained the average gray value of all images, as antenna house standard grayscale value.

3. ceramic radome pore as claimed in claim 1 and material rarefaction defect automatic testing method, it is characterized in that: step 2) in, in ceramic radome inside, light source is set, adopt ccd video camera, in antenna house outside, the whole different parts of antenna house is carried out to image acquisition, obtain antenna house different parts gray scale transmission image.

4. ceramic radome pore as claimed in claim 1 and material rarefaction defect automatic testing method, it is characterized in that: in step 3), on gray level image, the gray scale of defect area and background area has larger difference, the border of defect area is the discontinuous result of the gray-scale value of pixel, so can be detected by the mode of differentiate, adopt Laplace operator to process, to a continuous function f (x, y), Laplce's value that it is located at position (x, y) (being second derivative) is defined as:

${\mathrm{\Δ}}^{2}f=\frac{{\∂}^{2}f}{{\∂x}^2}+\frac{{\∂}^{2}f}{{\∂y}^2}$

In digital picture, by difference, be similar to, its expression is:

Δ ²f＝f(m+1,n)+f(m-1,n)+f(m,n+1)+f(m,n-1)-4f(m,n)

Its template is:

$\left[\begin{array}{ccc}0& 1& 0\\ 1& -4& 1\\ 0& 1& 0\end{array}\right]$

The all coefficient sums of template are 0, that is, if the value of template each corresponding position f (m, n) identical (there is no border), the response of operator is 0.

5. ceramic radome pore as claimed in claim 1 and material rarefaction defect automatic testing method, it is characterized in that: in step 4), after obtaining border, defect area, statistics obtains gray-scale value sum and the total pixel number of each defect area pixel, then by gray-scale value sum respectively divided by total pixel number, obtain the average gray of defect area, the total pixel number of each defect area being obtained by statistics obtains the area of defect area, and the average gray of defect area is made as T ₂, the average gray of the entire image of calculating in step 1) is made as T ₁, the computing formula of the loose rate δ of material is as follows:

$\mathrm{\δ}=\frac{T_2-T_1}{T_1}\×100\%$

By the area value of the loose rate δ of material and defect, judged the quality of ceramic radome.