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Image processing
4.1
General information
4.1
To form patterns that can be recognized, edges (transitions from light to dark or vice versa)
from the image are used. Although the algorithm extracts the edges automatically, the user
must make sure that the lighting is ideal for an image with good contrast; in other words, to
create models for recognition, it is essential to use the lighting correctly to achieve an image
with high contrast.
Note
The installation of suitable lighting often involves more time than all the other activities such
as securing the camera, connecting to the PLC, training, setting the correct triggers etc.
together. With metallic surfaces in particular, it is advisable to ask the advice of a lighting
expert due to the possible shine.
Part of object recognition is the recognition of the position of the object in the image.
The starting point is the midpoint of the image to which all coordinates relate. The top left
has the coordinates (-320; 240) and bottom right (320; -240).
If the object is not recognized, the position at the top left is output for x / y. The user should
always query whether or not this is an OK / N_OK evaluation and not rely on the x / y
positions!
Vision Sensor SIMATIC VS120
Operating Instructions, Edition 02/2006, A5E00757507-01
4
4-1
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