Patent US 3,980,814

An improvement in methods of image analysis is described whereby the time required for analyzing certain types of images can be substantially reduced. The invention utilizes the light integration characteristic of a television camera to combine a succession of images applied thereto into a single composite image. A video signal of the composite image is then obtained by scanning in the usual way. Analysis of the video signal is performed in a known manner after threshold detection. The invention is of application to the analysis of microscopic specimens which are generally black or dark grey and which include a few widely spaced white or light grey features, on which the analysis is to be performed. One embodiment utilizes a single scanner and switching devices for alternately producing scanning and not scanning. A second embodiment utilizes two or more scanners with switching devices for causing first one scanner and then the other to scan for reading and erasing whilst the other is quiescent and an optical diverting device for applying the images to the quiescent of the two scanners.