Computation time averaged one minute per real infrared image, almost all of it during
image processing, and this could be much improved by using C++ or Java packages rather than
Matlab. Thus there appears little advantage to processing time in attempting to reduce the
number of features considered, as by principal-components analysis; ships move slowly and are
not usually numerous in any one location, so that classification time is not too critical anyway.
Since performance was not much worse on the real images despite the presence of noise,
this suggests training on real images to eliminate the work of constructing detailed geometric
models. We need to examine performance for larger numbers of ship types or even individual
ships. We also need to eliminate common artifacts like ship shadows, reflections on the sea
surface, and heat from stacks that our preprocessing merged into the ship region.
Clearly performance of the neural network approach was much better than that of the
edge-histogram approach, and the techniques used are more robust. However, clearly some local
feature analysis would help performance judging by the mistakes made, and some of the edgehistogram
analysis could provide this. We are currently integrating work into a full ship-
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