Printed Image Quality Thresholds

The categories of tone and color reproduction, image definition, and interference patterns were used as a framework for exploring aspects of the perceptual quality and physical characteristics of printed images. The findings included: approximately 1,500,000 distinct colors may be reproduced by 4-color process printing; the halftone screening process should generated about 144 tone steps; screen rulings of 250 lines per inch produce optimal single color resolution for conventional screens; graininess and moirepatterns may be minimized, respectively, by conventional and stochastic screens; and, the human visual process loses both color discrimination ability and visual acuity with age. In order to realize optimum quality, it is necessary to balance the production conditions (materials and methods) to suit the characteristics of the original image, and the economic and production requirements of the printed product.