Contour mapping microdensitometer
P. Hariharan, M S Bhalla · Journal of Scientific Instruments · 1959
The instrument described in the present paper is basically a scanning microdensitometer in which a gating circuit is utilized in conjunction with an optical printing system to plot automatically a contoured density map of the photograph which is being scanned. The gating circuit used is comparatively simple and extremely stable and permits the insertion of as many contours as are required, at specified values of density.