Error diffusion using the web-safe colors: how good is it across platforms?

Accurate color rendering across displays is complicated on the World Wide Web by the color-handling properties of individual web browsers. However, the major browsers have all adopted a minimal color palette of 216 RGB triples, called the `browser-safe' colors, suitable for use with web page backgrounds and text, logos, cartoons, and line drawings. For naturalistic or photographic images, however, simple quantization to 216 colors can produce images with altered hues or color banding. We show that dithering with the browser-safe colors is a good strategy for such images, especially at spatial resolutions above 150 dpi. However, even if the RGB image is transmitted and received unaltered, the system gamma will affect appearance. Ambient lighting contributes to the rendered image's appearance, but does not mask the effects of differences in monitor gammas. The need for an image-rendering convention traceable to the CIE is underscored by these results.