Figure 12
From: Semi-automatic landmark point annotation for geometric morphometrics
The construction of the χ2between two scaled image patches. A linear fit to the joint intensity histogram of a pair of images I and J. Since both images contain noise, a datum at point A could be generated from any point C along the linear fit. However, if the standard deviations of the noise on I and J are equal, then the probability of generating data at A depends only on the perpendicular distance h to the linear fit, not on u.