An apparatus (2) for matching features in images of objects taken from
different viewpoints is provided comprising: an image buffer (60) for receiving
image data; and output buffer (62) for outputting pairs of matched features
and processing means (64-78) for processing received image data to determine
matched pairs of features in images. The processing means (64-78) includes
a detection module (72) for detecting features at a number of different
scales to account for the possibility that a feature in one image may correspond
to a larger or smaller feature in another image; a characterization module (74)
for generating characterization data for selected features where the characterization
data is substantially independent of changes of scale, and the effects of stretch
and skew resulting from viewing objects from different viewpoints; and a matching
module (76) for outputting as pairs of matched features, features which
most closely correspond to each other which are unambiguously better matches than
any alternative match between features in different images.