The Influence of Video Image Size and Resolution on Viewing-Distance Preferences

This article describes five experiments that were conducted to evaluate viewing-distance preferences as a function of video image size and resolution. Viewing-distance preferences are a key design parameter for work involving human factors in video teleconferencing, distance learning, and other multimedia applications. In addition, viewing-distance preferences have been treated as a subjective measure of image quality and used in ongoing discussions of proposed standards for high-definition television (HDTV). Based on previous literature, it was hypothesized that the ratio of viewing-distance preferences to image height would be a constant, would vary based on image resolution, and would average around 7 for standard NTSC video (with 525 scan lines of resolution). Contrary to the predictions, the data showed that the ratio decreases as image size increases, and that the ratios are relatively uninfluenced by image resolution. The data for the five experiments were combined to generate a guideline for estimating viewing-distance preferences across a wide range of video image sizes.