Operators sometimes employ clever and often low-tech strategies for bypassing a vision-based label quality-control system. Sometimes they simply shut off the system and let products go through. Other timesCONTROL ENGINEERING China版权所有, they place an image of a good product in front of the camera to allow the lesser quality labels to go by. Makers of a global brand of personal care products recently found some of its own operators were breaking the rules this way.
　　The company asked CI Vision (Aurora, IL), for a new vision inspection system with a mechanism to prevent plant staff from bypassing it. CI Vision’s “Anti-Vision Circumvention Technology” turned out to be a useful feature of its Pro Series inspection system.
　　The base model of the Pro Series system has two cameras in steel housings connected via the GigE Vision camera interface standard. Up to four cameras can be installed控制工程网版权所有, and the vision system is controlled either by a custom-built PC or Matrox 4Sight X industrial PC. The CIVCore software that controls the image acquisition and inspection tasks is built from the Matrox Imaging Library (MIL).

　　CI Vision's label image acquisition and inspection software is built from the Matrox Imaging Library
　　To inspect a product batch, an operator sets up the inspection type on a touchscreen. When an image is acquired, normalized grayscale correlation is used to determine the presence or absence of the label itselfwww.cechina.cn, as well as the location of the label’s region of interest (a bar or matrix code, or a lot number). Code 128 bar and two-dimensional data matrix codes are read by MIL’s code module for correctness. The CIVCore’s OCV modulewww.cechina.cn, which is built from MIL’s pattern matching and image processing modules控制工程网版权所有, reads text-based lot numbers and label control numbers.
　　The Pro Series system features an optional tool that detects if the same label appears on the front and back of the product. The system uses the search model from the presence/absence feature to determine which label is in front of Came