Overview in PDF format - Tallinna Tehnikaülikool

correcting image distortions in optical, electrical and digital parts of the measuringsystem.In bitmap images each pixel is treated individually. For image recognition andmeasurement, it is important to know relations between different pixels. The firststep in this direction is an analysis of the small neighbourhood of each pixel.Program Terik uses two neighbourhood operators: non-linear median filter forremoving noise, and a variation of Roberts filter for edge detecting. For fasterimage computing and deselecting non-interesting areas only a part of picture can beselected for image manipulation. All results can be saved into formatted text filesfor future analyzing in other programs (MS Excel, etc). Experimentally themeasurement time was reduced from 90 min (by conventional microscope) to 3 min(by using video measurement system). In Fig. 2.7 a screenshot is shown of theprogram Terik working window, written in Visual Basic.Figure 2.7 Working windows of the image processing program TerikA smooth, uniform illumination system is the most important factor influencingmachine vision (Tervola, 2001), therefore a cold light source with preferablygooseneck fibre optics is essential. Variations in radiation affect the imageformation system, thus causing difficulties in boundary detection. As the authors’experience shows, the unstable illumination direction can influence themeasurement results about 10 %. The problem arises in IMS due to chip flowinfluences.The Terik solution has been successfully used in several industrial researches,e.g. to reduce burring in milling PLC plates for electronic industry, and to estimatethe influence of counter-clockwise and clockwise milling on burr formation.22