CN102937592A - 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

Inevitably there are pore and material rarefaction defect behind the thin-walled ceramic radome production, but in present 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, can't guarantee the detection quality of product.

Summary of the invention

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

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

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

Described ceramic radome pore and material rarefaction defect automatic testing method, in the step 3), for pore and material rarefaction defect district are carried out area statistics, need to obtain first the border of defect area, so carrying out the border proposes to process, the gray scale of defect area and background area has larger difference on gray level image, the border of defect area is the discontinuous result of the gray-scale value of pixel, so can it 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:

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

Be similar to difference in digital picture, 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:

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

All coefficient sums of template are 0, that is, if in the value identical (not having the border) of each corresponding position f (m, n) of template, then the response of operator is 0.

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

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

Judged the quality of ceramic radome by the area value of the loose rate δ of material and defective.

The present invention compared with prior art, its advantage is: adopted image to process automatic testing method and come 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 pore and the detection of material rarefaction defect, in ceramic radome inside light source is set, automatically carry out image acquisition at the outside ccd video camera that adopts of ceramic radome, obtain the gray scale transmission image of ceramic radome different parts, several gray level images of continuous acquisition different parts, every width of cloth image is carried out gray-scale statistical, calculate total gray-scale value of all images, add up the pixel value of every width of cloth image, calculate the total pixel number of all images, obtained the average gray value of all images divided by total pixel number by total gray-scale value, as antenna house standard grayscale value, here 20 width of cloth images have been gathered, the antenna house standard grayscale value that calculates: T ₁=80.

In ceramic radome inside light source is set, adopts ccd video camera in the antenna house outside the whole different parts of antenna house to be carried out 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 area statistics, need to obtain first the border of defect area, so carrying out the border proposes to process, the gray scale of defect area and background area has larger difference on gray level image, the border of defect area is the discontinuous result of the gray-scale value of pixel, so can it be detected by the mode of differentiate, adopt Laplace operator to process, to a continuous function f (x, y), its Laplce's value (being second derivative) of locating at position (x, y) is defined as:

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

Be similar to difference in digital picture, 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:

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

Notice that all coefficient sums of template are 0, that is, if in the value identical (not having the border) of each corresponding position f (m, n) of template, then the response of operator is 0.

Step 2): after obtaining the defect area border, 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 that is obtained by statistics obtains the area of each defect area, and area is S=28mm ², then the computing formula of the loose rate δ of material is as follows:

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

Judged the quality of ceramic radome by the area value S of the loose rate δ of material and defective.

Claims (5)

1. a ceramic radome pore and 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) the defect area Boundary Extraction is processed; 4) area of calculating defect area average gray and defect area, the defect area gray-scale value and the entire image average gray that obtain compare, be used 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 the step 1), in ceramic radome inside light source is set, automatically carry out image acquisition at the outside ccd video camera that adopts of ceramic radome, obtain the gray scale transmission image of ceramic radome different parts, several gray level images of continuous acquisition different parts, every width of cloth image is carried out gray-scale statistical, calculate total gray-scale value of all images, add up the pixel value of every width of cloth image, calculate the total pixel number of all images, obtain the average gray value of all images by total gray-scale value divided by total pixel number, 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 the antenna house outside the whole different parts of antenna house to be carried out 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 the step 3), the gray scale of defect area and background area has larger difference on gray level image, the border of defect area is the discontinuous result of the gray-scale value of pixel, so can it 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:

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

Be similar to difference in digital picture, 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:

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

All coefficient sums of template are 0, that is, if in the value identical (not having the border) of each corresponding position f (m, n) of template, then 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 the step 4), after obtaining the defect area border, statistics obtains gray-scale value sum and the total pixel number of each defect area pixel, then by the 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 that is 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 the step 1) is made as T ₁, then the computing formula of the loose rate δ of material is as follows:

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

Judged the quality of ceramic radome by the area value of the loose rate δ of material and defective.