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30 SMT Magazine • November 2014 and lenses, some corrections have to be imple- mented in order to attain one coordinate sys- tem for both cameras. Here the individual dis- tortions of each camera and lens combination must be corrected prior to any further opera- tion. Another way to adjust the unit before any repair takes place is to calibrate the individual light conditions. As anyone can understand, an open unit with cameras on board is influenced by environmental light conditions, which can be recognized and calibrated. Extreme changes in the surrounding light can be compensated and the built-in LED illumination is adapted to the new light situation. By doing this, the rework system can generate the best contrast images and precise placement in nearly any en- vironment. To find individual structures in images, like pins of a quad flat pack (QFP), a typical image processing procedure is "edge detection," a method developed by John Canny, an Austra- lian scientist who developed the Canny Edge Detector algorithm in 1986. new PLacement tecHnoLogy For rework systems continues feaTure Figure 3: parts image and Canny edge Detector results with different thresholds. (Source: wikipedia.org [2] )