Resolution-Dependence of Perceived Contrast of Textures

Spurred by technological improvements, displays (as well as printers) are increasingly available in a wide range of resolutions. Increased resolution improves perceptual quality in at least two different ways: reducing the perceived contrast of undesirable artifacts (such as halftoning or dithering textures), and increasing the perceived contrast of desirable image features (particularly when rendering text and high precision graphics). Much of the past literature addresses questions of how to optimize one or both of these for a given resolution, but there is little guidance on tradeoffs when the resolution itself is variable. In this paper, we present an analytic framework for quantifying how the perceived visual contrast of textures changes with resolution, and a simple, tractable model that accurately predicts visual contrast of grayscale-rendered text at different resolutions. These contrast metrics provide a solid basis for evaluating the effectiveness of grid-fitting and similar techniques for perceptually tuned grayscale font rendering, and can also be a useful tool for evaluating engineering tradeoffs such as choosing an optimum resolution relative to cost, speed, or bandwidth constraints. 1