Resolution and bit depth: how much is enough?
R. Victor Klassen, Kalpana Janamanchi · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2000
We describe results of experiments studying the tradeoff between resolution and bit depth. Images in the experiments were printed on a high resolution imagesetter, eliminating most, if not all, device effects. They were first converted from PostScript to antialiased rasters at one of a set of resolutions, then converted from 8 bit to n bits for some value of n less than 8. Before printing, they were converted back to 8 bits and scaled up to printer resolution, then halftoned for printing. We were measuring human response to a system that had a bandwidth bottleneck somewhere upstream of the printer, and sophisticated resampling and halftoning at the printer itself. The images, typical of those used for critical evaluation of hard copy, contained text, analytical test targets, synthetic graphics and pictorial images. We found bit depths and resolutions beyond which no further improvement was observed, typically somewhat higher limits than previously believed. We also compared methods of font hinting for antialiased text, and found that font hinting improves text only at one bit per pixel, degrading it at higher bit depths.