CN101806756B - Method for detecting PCB (Printed Circuit Board) by using X-ray - Google Patents

Abstract

The invention relates to the relative technical field of PCB (Printed Circuit Board) detection methods, in particular to a method for detecting a PCB by using X-ray. The method for detecting the PCB by using the X-ray mainly comprises the following steps of : imaging the PCB through the X-ray to obtain an imaging picture; (11) making a statistical grayscale histogram according to the imaging picture; (12) determining a grayscale range [A,B] at a place where the pixel distribution is densest in the statistical grayscale histogram; (13) determining the grayscale range [A,B], inputting a color gradation range and outputting the color gradation range by a user; and (14) stretching the grayscale range [A,B] to a new grayscale range [Z1,Zk] to obtain a new imaging picture. The invention ensures that the image is clearer and more recognizable and can be more rapidly recognized.

Description

A kind of method that detects PCB with X ray

Technical field

The present invention relates to the correlative technology field of PCB detection method, particularly a kind of method that detects PCB with X ray.

Background technology

The x-ray imaging step mainly is made up of the following aspects:

X-ray tube---image intensifier---camera---de-noising processor---display

Present circumstances is to the image of display, to depend on the quality of preceding four components and parts.However, even improved the quality of four components and parts, image effect has improvement, but still undesirable.The client requires to promote clearness always.Sharpness is not enough.Be the shortcoming of present similar X-ray examination machine.Sharpness is meant that " naked eyes " can not tell between the image lines or the difference between the image shade of grey, that is the fine degree between the resolution of image level scenic focal point material point or the slight level texture or the image shade of grey.Its resolution is higher, and image appearance must be more careful, and sharpness is higher.

In order to improve X-ray operating personnel's condition of work, use low intensive x-ray exposure, but the imaging gray level of obtaining like this concentrates on the dark space, many image details can't be seen clearly, the interpretation difficulty.

Summary of the invention

The invention provides a kind of method, to solve in the prior art, through the unsharp technical matters of x-ray image of X-ray examination PCB acquisition with X ray detection PCB.

The technical scheme that the present invention adopts is following:

The method of a kind of usefulness * ray detection PCB, said method comprise that through X ray PCB being carried out imaging processing obtains the picture that forms images, and said method comprises:

(11) to imaging picture statistics grey level histogram;

(12) tonal range [A, B] is confirmed in the most intensive place of pixel distribution in the statistics grey level histogram;

(13) user confirms input levels scope [minA, MaxB], output levels scope [minOut, maxOut];

(14) stretching tonal range [A, B] is to new tonal range [Z ₁, Z _kThereby] obtain new imaging picture.

As a kind of preferred version, said step (13) adopts following method stretching tonal range [A, B] to new tonal range [Z ₁, Z _k]:

The mapping of foundation from former gray scale z to new gray scale Z ', as shown in Figure 1, adopt following formula:

$Z^{\&prime;}=t\left(z\right)=\left\{\begin{array}{cc}{Z}_1=\min A& Z<\min A\\ \frac{Z-\min A}{\max B-\min A}*(\max \mathrm{Out}-\min \mathrm{Out})+0.5& \min A\&le;Z\&le;\max B\\ Z_{k=\max B}& Z>\max B\end{array}\right.$

As further preferred version, said step (11) is preceding, also comprises the imaging picture is strengthened and/or noise reduction process.

As further preferred version, it is characterized in that the concrete steps of said step (14) are following:

(41) adjustment Z ₁And Z _kValue, if all Z of traversal in 0～255 scope ₁And Z _k, then withdraw from, otherwise execution in step (42);

(42) stretching tonal range [A, B] is to new tonal range [Z ₁, Z _kThereby] obtain new imaging picture;

(43) if useful image in the new imaging picture and background image can obviously be distinguished, then withdraw from, otherwise execution in step (41).

As further preferred version, said useful image is that PCB goes up the metal level that applies, and background image is meant the base material imaging moiety of PCB.

As further preferred version, in the said step (43), to distinguish through the articulation index of more useful image and background image, concrete steps are following:

When articulation index surpasses pre-set threshold, think that then useful image and background image can obviously distinguish, withdraw from step (43), otherwise, think that useful image and background image can not obviously distinguish continuation execution in step (41).

The present invention has the following advantages:

(1) be that image is more clear and legible, quick identification more.Therefore can take the software enlarged image to observe significantly.Simultaneously, boost productivity more greatly because of identification.

(2) be to reduce the error that human factor causes in the measurement.When clear picture can make measuring operation, as when drawing the distance of center circle of round gaging hole, can seek the border more accurately, reduce personal error.

(3) be to reduce production costs greatly and reduce unnecessary loss.Can carry out image definition and regulate as the case may be, each different emphasis of printed wiring board are observed and analyzed.Obtain the more quality information of wiring board.Thereby more accurately control product quality.Reduce production costs and reduce unnecessary loss.

(4) be the raising of image definition, can improve the X-ray tube lifetime to a certain extent.During for example with former software test, when surveying certain slab, the X-ray tube voltage needs 44KV; And when adopting new software, only need 40KV just passable.Therefore, the X-ray pipe can come work with low slightly voltage.This played a role to the life-span of improving the X-ray pipe.

(5) be to widen the field range that X-ray is observed to a certain extent.Present situation is that sharpness has loss when strengthening the visual field.Software after the improvement has remedied the loss of sharpness.Can widen targetedly * field range that light is observed.

Description of drawings

Fig. 1 expands to tonal range [Z from tonal range [A, B] ₁, Z _k] functional arrangement;

Fig. 2 be to PCB * radial imaging, through to strengthening the image that collects after the processing such as noise reduction;

Fig. 3 is to Fig. 2 gray-scale statistical histogram result;

Fig. 4 is for being stretched to Fig. 2 tonal range the image under [Z1, Zk] tonal range;

Fig. 5 is the corresponding color range statistic histogram of Fig. 4;

Fig. 6 strengthens useful view data for Fig. 2 process, the design sketch after the weakening background.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment the present invention is carried out further detailed explanation.

The concrete steps of present embodiment are following:

1) extracts the x-ray imaging of PCB targetedly,, collect image as shown in Figure 2 after the processing such as noise reduction through to strengthening;

2) Fig. 2 is carried out gray-scale statistical and obtain histogram as shown in Figure 3;

3) according to following formula

$Z^{\&prime;}=t\left(z\right)=\left\{\begin{array}{cc}{Z}_1=\min A& Z<\min A\\ \frac{Z-\min A}{\max B-\min A}*(\max \mathrm{Out}-\min \mathrm{Out})+0.5& \min A\&le;Z\&le;\max B\\ Z_{k=\max B}& Z>\max B\end{array}\right.$

Wherein, [A, B] comes out image tonescale, and [minA, MaxB] color range scope is user expectation and a scope setting, and it is greater than [A, B].In [minA, MaxB], can regulate [A, B] through pulling software slider bar and expand color range scope [Z to ₁, Z _K], so just increased the color range scope.Promptly by [A, B] → [Z ₁, Z _K].

Output levels scope [minOut, maxOut] is the scope that the user sets, and promptly is the target setting value of output.Generally be set at [0,255].

Improve contrast through stretching concentric circles tonal range, be illustrated in figure 4 as and be stretched to two images under the different tonal ranges, Fig. 5 is its corresponding histogram, can find out, the image of useful view data intensity profile wider range is more clear;

4) through improving contrast, strengthen useful view data, weaken background, thereby more easy separation goes out the view data that we need.Like Fig. 5, exactly Fig. 2 is taked Flame Image Process, through image grey distribution range width being regulated an image of choosing.Increase concentric circles profile gray scale, reduced the background gray scale, selective after software algorithm is handled, observe distinct image.Compare clear picture, sharp outline with Fig. 2.

Claims (4)

1. one kind is detected the method for PCB with X ray, and said method comprises that through X ray PCB being carried out imaging processing obtains the picture that forms images, and the imaging picture is strengthened and/or noise reduction process, and said method comprises:

(11) to imaging picture statistics grey level histogram;

(12) tonal range [A, B] is confirmed in the most intensive place of pixel distribution in the statistics grey level histogram;

(13) user confirms input levels scope [minA, MaxB], output levels scope [minOut, maxOut];

(14) stretching tonal range [A, B] is to new tonal range [Z ₁, Z _kThereby] obtain new imaging picture, it is characterized in that,

Said step (14) adopts following method stretching tonal range [A, B] to new tonal range [Z ₁, Z _k]:

The mapping of foundation from former gray scale z to new gray scale Z ', adopt following formula:

$Z^{\&prime;}=t\left(z\right)=\left\{\begin{array}{cc}{Z}_1=\min A& Z<\min A\\ \frac{Z-\min A}{\max B-\min A}*(\max \mathrm{Out}-\min \mathrm{Out})+0.5& \min A\&le;Z\&le;\max B\\ Z_k=\max B& Z>\max B\end{array}\right.$

2. the method with X ray detection PCB according to claim 1 is characterized in that, the concrete steps of said step (14) are following:

(41) adjustment Z ₁And Z _kValue, if all Z of traversal in 0～255 scope ₁And Z _k, then withdraw from, otherwise execution in step (42);

(42) stretching tonal range [A, B] is to new tonal range [Z ₁, Z _kThereby] obtain new imaging picture;

(43) if useful image in the new imaging picture and background image can obviously be distinguished, then withdraw from, otherwise execution in step (41).

3. the method with X ray detection PCB according to claim 2 is characterized in that, said useful image is that PCB goes up the metal level that applies, and background image is meant the base material imaging moiety of PCB.

4. the method with X ray detection PCB according to claim 2 is characterized in that in the said step (43), distinguish through the articulation index of more useful image and background image, concrete steps are following:

When articulation index surpasses pre-set threshold, think that then useful image and background image can obviously distinguish, withdraw from step (43), otherwise, think that useful image and background image can not obviously distinguish continuation execution in step (41).

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