Edited by author 10-25-2001 05:00 AM
I also thought their approach was kinda cool. The features seemed strange for a bit, but they sholud work as edge/gradient detectors (a and b) center-surround detectors (c), ect. While they do mention that the rectangular features are more limited than 'steerable' features, they point out that rectangular ones are rich enough to get the job done. The important point, though, is that with the integral image technique, the rectangular features can be computed FAST. If you have to use a couple rectangular features to get the same information as a single more complex feature that takes longer to calculate, you still come out ahead.