METAPHASE SPREAD DETECTION AND FOCUS USING CLOSED CIRCUIT TELEVISION

Abstract

Automatic focus and detection of metaphase chromosome spreads have been implemented in an automated light microscope system and performance has been evaluated. The video signal from a standard closed circuit television camera is used to generate focus quality and spread presence parameters that are input to a computer. The computer, through its operating software, controls lateral and vertical motion of the microscope stage to search the slide for metaphase chromosome spreads and to focus them. The video signal processing required to generate the parameters, its implementation and the operating software are described. The evaluation of spread detection performance emphasizes the need for well prepared slides with clean backgrounds. The performance of two methods of obtaining a focus parameter is compared. The first method involves measuring the high spatial frequency content of the image; the second method uses the distribution of optical density within the image.