Before an Image Processing System is Used

Abstract

An image processing system can work dependably only if it is provided with appropriate images for evaluation. Such an image must have sufficient contrast between the object to be inspected and its background and sufficient sharpness. In order to ensure this, a vision system must be calibrated before use. The same procedure can be also used for self-test of the vision system during operation. During calibration, a dynamic check of illumination and sharpness of the taking is performed. It is known that all measurements on an image are displayed in pixels. These values are usually converted to centimetres, metres, or other measurement units in order to facilitate human understanding and documentation. This means that a geometrical calibration of a vision system is necessary prior to utilization. A conversion factor for a measurement unit to pixels has to be calculated here. In parameterization of a vision system intended to detect certain objects or defects, permissible sizes of those objects are defined. First, these sizes must be adjusted to the technical parameters of the vision system and the feeding mechanism as well as to the properties of the parts to be inspected to ensure an optimal solution of the task.