Real-time visual inspection of moulded plastic drippers

An automated inspection method is sketched and its parallel implementation on a MIMD multiprocessor is discussed. The method is based on a segmentation of gray level views of the test object and on the extraction and measurement of meaningful blobs from the segmented images. Segmentation is performed processing the histogram of pixel intensities; blob extraction is based on the application of the distance transformation to interest regions. The method is able to detect shape defects affecting a type of moulded plastic drippers; typical defects revealed are: incompleteness, excess of moulded material along the joint lines, incompleteness of a labyrinth-like mask moulded on the dripper surface. The algorithm consists of several steps that can be easily implemented on a MIMD architecture using both a shared or a distributed memory approach. The implementation on the hierarchical shared memory ViP multiprocessor is discussed; drippers can be efficiently analyzed on this kind of system, configured with 3 clusters of 4 processors each, at the production rate of two per second, making possible single piece quality certification.