Abstract: In an electromechanical engraving system, rotogravure calibrating apparatus automatically adjusting the engraving operation of an engraving-head stylus of the system in real time by calibrating a stylus-actuating engraving signal according to a calibration factor relating printed image density to engraved cell depth for a designated engraving screen ruling corresponding to printed image resolution. The calibrating apparatus includes a cell observation and measuring device which obtains data for calculating cell size by imaging the form of individual test cells engraved by the stylus into the surface of a rotogravure printing cylinder, and an engraving signal calibrator which adjusts engraving signal control parameters according to the cell size calculation and to the calibration factor.