AL1_SiplaceX-en.pdf - 第300页

1 - 10 S tudent Guide SIPLACE X 8 Siplace Vision Edition 02/2005 10 8.1.9.1 The histogram method Each of the teach picture is brightness normed a middled histogram is determined. The m odel consists on a histog ram for p…

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Student Guide SIPLACE X

Edition 02/2005 8 Siplace Vision

The camera moves to the programmed bad mark coordinates. The dimension of the evaluation

area have to be programmed only one time.

Fig. 8.1 - 2 Triangle teached as a bad mark (negative to skip placement)

For the negative bad mark move the camera above another fiducial or:

teach camera manual to the position of the sticker; or:

mark the positive bad mark respective.

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Student Guide SIPLACE X

8 Siplace Vision Edition 02/2005

8.1.9.1 The histogram method

Each of the teach picture is brightness normed a middled histogram is determined. The model

consists on a histogram for positive respective negative case. At the classification is the histogram

of the evaluation of the actual picture calculated and deviation to the histograms of the pos. /neg.

model is determined. The picture histogram is assigned to the class where the smallest difference

is.

Following show the process with an example:

Teach picture "placement": bright circle on dark background.

Teach picture "no placement": fiducial is colored with black 'Edding'

Picture to classify

red length bar: teached histogram

"no placement"

green length bar: teached histogram

"placement"

blue length bar: actual histogram of

the evaluation picture

cross bar: distance to teach-histo-

gram.

here has the blue histogram a low dis-

tance to the green bar --> "place"

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Student Guide SIPLACE X

Edition 02/2005 8 Siplace Vision

Charachteristic: 8

· => Very quick procedure

· => Classification based on global characteristics of the picture therefore is no defined shape

necessary

· => Is an extended contrast method of SW-Platform II (50x SW)

· => Independent on changing in brightness

· => It has to be sure that the evaluated picture is on the same position of the board than the

Teach picture; this mean before bad mark recognition is the PCB-position recognition done.

· => The method could be changed in 'Geometry menu'.

8.1.9.2 The brightness method

The brightness method is a general method, which is influent from brightness changing at the

PCB-Cameras in the line.

At this method is the model information learned by teaching the characteristic of the positive and

negative case is determined. From all the procedures this one is the simplest. From the teach pic-

tures of the positive / negative case is the respective middle brightness per picture determined.

The system defines 2 brightness limits. This split the gray values into three areas: negative case

- in doubt - positive case. At the classification is the middle brightness of the evaluation range is

determined and according the two thresholds to one of the three areas assigned.

Result drawing of classification: the blue length bar shows the evaluated difference of the bright-

ness value and show, that it was classified for "no placement".

Characteristic: 8

· => Very quick procedure

· => Classification base on global characteristics of the picture, therefore no defined shape is

necessary

· => Sensitive against changing of brightness, therefore the use in lines with different PCB-cam-

era brightness is critical.

· => PCB recognition before bad mark recognition necessary.

Brightness 1

Range

’placement’

Range ’NO

placement’

In doubt