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M odern desktops and application development environments give the user the ability to interactively select colors, fonts and graphical objects, but do not offer the user guidance in making these selections. Consequently, the user is free to produce illegible, unaesthetic, and jarring results. For example, the user can select dark blue text on a black background, fuscia and scarlet windows in the same application, and button text which is truncated because it doesn't fit on the button geometry. With additional iterations through the design process, users can often converge on a reasonable selection of colors, fonts and graphical objects, but this process is often time-consuming and frustrating, and may not result in a particularly good set of selections. Furthermore, the users of these systems may not be particularly sophisticated in issues of legibility, color harmony, or graphical design. Furthermore, when these users have difficulties, they very often interpret these as system failings, resulting in service calls to manufacturers. In a recent example, a user called to complain that his computer was broken because there was no text under his icons. He had inadvertently selected white for both the screen background color and the icon text color. In 1993, we introduced a general architecture for adding guidance to interactive systems (Rogowitz and Treinish, 1993) which we have extended to the domain of user interface design (Rogowitz and Rabenhorst, 1993) in a system called CRAFT (Color Rule and Font Tool). In this approach, the choices for each operation (e.g., selecting background color, selecting text color) are constrained by perceptual and aesthetic "rules". In this architecture, all related operations are linked, which means that every time the user makes a selection, the impact of that choice is reflected in the selections for other operations. For example, if the user selects a color for a window background, that information is fed back to the operation for selecting text color, where legibility rules use this information to constrain the set of text colors to those which provide sufficient luminance contrast for good legibility. This network of linked, intelligent operations help guide the user through the complex design space of colors and fonts. In this paper, we enhance the CRAFT system by developing the relationship between the rules and the information which drives them, with a special focus on fonts and font/color interactions.
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