A pressroom densitometer measures dot area based on the total amount of light reflected from a halftone tint vs. blank substrate and 100% image or ink coverage.
When used to measure printing plates, which may have a low contrast ratio between image and nonimage areas, pressroom densitometers have “light gathering effects” that necessitate programming an n-factor to accurately measure halftone dot size. This Yule-Nielsen factor has to be determined for each plate type and the different dot area regions, which leads to less efficient measurement workflow.
The PlateScope and/or icPlate2, in contrast, act as a microscopic digital cameras. They photograph the dot pattern on plates, distinguishe the dots from the background, then calculate dot area based on the perimeter of the dots.