
384 Chapter Nineteen Visual Generalization in PBE
Our current intuitions about the design of a visual generalization system
for PBE lean toward a broad-based approach that applies pixel-level opera-
tors, as in TRIGGERS, where appropriate, but also generates higher-level in-
formation inferred from the pixel data, as in VisMap. If the user knows what
a particular piece of information looks like on the screen but does not know
how to describe it, then a low-level pixel-based approach may be the best
choice. If displayed information needed by a program is not provided by
formal techniques and its visual appearance is complicated, ...