A system and method for performing optical inspection are provided. At
least one "invariant feature" of an object design is determined, and such
invariant feature is used in inspecting objects having the corresponding
design. An "invariant feature" is a feature that is invariant certain
transformations occurring in a captured image of an object under
inspection, such as brightness, color, and/or other transformations in
the captured image. Accordingly, an inspection template may comprise
information corresponding to at least one pre-selected invariant feature
of an object's design. In certain embodiments, the template is a shape
description of a feature that provides an intrinsic invariance to a
specified set of basic transformations. Accordingly, the amount of pixel
values stored in a template may be minimized, which minimizes the number
of pixel comparisons made between a captured image of the object under
inspection and the inspection template during the inspection analysis.