A single spatial filter function closely replicating the contrast sensitivity of the visual system is
used to predict the visual detection thresholds for narrow lines and dots and small amounts of edge blur.
Both the predictions for lines and for edge blur are consistent with published data. Maximum
differences with delta function lines and dots yield limits for distinguishing the actual width of lines and
dots. A caution on spot size constraints based on fidelity of line width <"20 microns is given (other
constraints are mentioned). Series expansions within the mathematical definitions reveal that the
detection thresholds are simply related to polynomial power integrals (i.e. moments) of both the object
profile and the visual system spatial filter function. An argument is presented that a halftone screen can
not be free of screen-to-raster artifacts at addressabilities <'-1200 d.p.i. if the screen is not rational
tangent. Published limits on the visibility of edge raggedness suggest that stairstepping at
addressabilities <-3700 d.p.i. should never be a concern.
Henry A. Kelley,
"Imagesetter requirement limits based on a simple model of visual acuity", Proc. SPIE 1670, Color Hard Copy and Graphic Arts, (1 May 1992); doi: 10.1117/12.2322238; https://doi.org/10.1117/12.2322238