Festo SBSC-EN, Руководство пользователя

Страница: 113 / 365

Vision Sensor SBSI/SBSC-EN, 8062650 - 1607b - 13/09/2016 Page 113
Vision Sensor Manual
If the same detector is placed now at a position where the metal contact is missing it leads to a negative
result. As, between the black surrounding and the now visible black background of the contact, the
contrast value here is low.
Function detector Contrast
The dark and the bright pixels are evaluated according to their amount and their intensity / brightness.
The position of the bright or dark pixels is not relevant.
Fig. 105: Contrast examples
Fig. 106: Contrast explanation
4.6.3.6 Grey detector
Next topic. Brightness detector (Page 117)
Grey level application (Page 115)
At this detector in the first step the range of accepted grey values is defined by setting the two limit
sliders of parameter “Grey level”.
In the second step the share of the search area (in %) which must be covered by pixels with the grey value
inside the definition made in step 1, is defined with the parameter “Threshold” to achieve a positive result.
By the respective invert function all possible combinations can be defined, also those where the relevant
grey values are only at the upper or lower border of the range of values. The position of the respective
brought or dark pixels is not relevant.
With the parameter „Overlay“ pixels can be marked in a certain colour as an aid to select pixels / regions,
which have a grey value inside (valid pixels), or outside (invalid pixels) the range set in „Grey level“. In this
way pixels which are not covered with the settings / range of grey values can be detected very easily.