Patent US 4,183,013

A system for sequentially processing an image in order to identify objects in the image, and extract a variety of shape features of the identified objects. The system includes an image preprocessor, a controller, an object boundary resolver and identifier and a feature extractor. The image preprocessor scans the image and generates digital scan line signals wherein each bit is representative of a detected characteristic of an elemental region associated with a current scan position in the image. The object boundary resolver and identifier identifies object edge points from the digital scan line signals and maintains edge point data records representative of the position of the edge points in the two most recent scan lines. The resolver and identifier further processes the edge point data to identify continuation, creation, termination and merge conditions for the various objects within the image. For each of the identified objects, the feature extractor determines the presence of various shape features for the identified objects. These features include object count, perimeter (P), area (A), P.sup.2 /A, moments, neck features and segmentation features. All the features identified by the feature extractor are extracted in a single pass, sequential processing of the image.