Steps in image processing. Raw image (a) is reversed, then filtered to minimize background features (b), then thresholded, and holes filled (c), features are skeletonized (reduced to 1 pixel width) (d) and short segments pruned away (e). The intersections of these lines are used to register the model with this image, and the model modified to fit the grey scale image in (c). The final result with the spline model overlayed on it (f). The white circles are the two landmarks digitized by the operator. Wing is from the Wabasso population of D. melanogaster.
Houle et al. BMC Evolutionary Biology 2003 3:25 doi:10.1186/1471-2148-3-25