APPARATUS FOR MEASURING PERCENTAGE DOT IN PRINTING AND THE LIKE APPLICATIONS

摘要

Apparatus for determining the percentage dot in half-tone images incorporates a CCD camera, the output of which is processed by electronic circuitry in such a way that the circuitry counts the number of light sensitive elements of the CCD array providing a "black" level signal, derives from that count a value for percentage dot and displays the percentage dot values arrived at on a display. The circuitry may include means for determining or adjusting the threshold CCD signal below which a "black" level will be assumed and above which a "white" level will be assumed. The apparatus is preferably housed within a housing which can be manipulated by hand and which has aligned windows (18, 22) in its lower and upper surfaces through which the half-tone image being monitored can be viewed and an angled half-silvered mirror (20), between the windows (18 and 22), arranged to direct some of the light from the image being monitored through a lens system (24) onto CCD array (26).