ability is calculated for two sets of feature
frames FRAMESA and FRAMESB detected in a reference image IMAGEA and a second
image IMAGEB. The two images are assumed to be related by a known homography
H, mapping pixels in the domain of IMAGEA to pixels in the domain of IMAGEB.
The test assumes static camera, no parallax, or moving camera looking at a
flat scene. </p>

<p>A perfect co-variant feature extractor would detect the same features in
both images regardless of a change in viewpoint (for the features 