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UBC Theses and Dissertations

Computer-controlled microscope for the automatic classification of white blood cells. Gabert, Howard Frederick

Abstract

A microscope was interfaced to a PDP-9 computer in order to develop techniques suitable for on-line classification of white blood cells. The computer visual-input system is composed of an image dissector optically coupled to a microscope used in a transmitted light mode. The position of the slide under the microscope and the fine focus control are controllable from the computer. A technique of auto-focusing was developed to efficiently focus the microscope under computer control. This algorithm is described in detail, followed by a discussion of the physical factors that affect the performance of this technique. A method of locating or isolating the leukocytes (white blood cells) is described next. A constant, referred to as the "contrast ratio' is used to extract the threshold for the nuclei of the leukocytes based on the average background intensity. Finally, contour tracing and curvature function extraction are used as a means of testing the system. A specific test is conducted to obtain a comparison of the system's efficiency as compared to that of "manual" techniques used by a technician. The system described here is not only suitable for automatic leukocyte classification, but could also be used for many other routine tests requiring the examination of microscopic cells.

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