Determination of image sharpness parameters of graphic art films using large-area densitometry

This paper was presented at the Intemational Congress on ‘Imaging Science’ (ICPS’98) held at the University of Antwap in September 1998.

Abstract

A method is described for deducing the image spread parameters of graphic arts films from large-area density versus log exposure plots obtained by contact exposures through a linear ‘tint’ test object. The success of the method depends on the high contrast and maximum density of the film, the design of the test object and the effectiveness of the antihalation layer. The method involves the calculation of the exposure inside and outside the geometrical lines using light-scattering theory and the dependence of developed linewidth on incident exposure. It is shown that the slope of the upper part of the developed linewidth versus log exposure curve depends almost entirely on the optical properties of the film whereas the absolute value of the linewidth depends on both its optical and chemical properties. It is shown that the optical and chemical components of image spread can be determined separately from a single experimental curve of developed linewidth versus log exposure derived from large-area densitometry. It is shown that the performance of the anti-halation layer can also be assessed from the same experimental data.

Key Words:

• Image sharpness
• Graphic arts films
• Large-area densitometry
• Light-scattering theory

Notes

This paper was presented at the Intemational Congress on ‘Imaging Science’ (ICPS’98) held at the University of Antwap in September 1998.