Instrumentation for the Measurement of Slur and Fill-in on a Lithographic Web Press.

The two contributors to dot gain, slur (directional dot increase) and fill-in (radial dot increase), are determined dynamically on a web press along with the solid ink density. These determinations are computed values based on density measurements made on a specially designed test object under the control of a programmable calculator. The derived values of slur, fill-in and solid ink density are graphed by a plotter also controlled by the calculator during the press run, producing a real time display of these parameters.