A computer-implemented image processing technique for selectively recovering the features of an original CAD model after the original CAD model has been converted to a digitized image and a new CAD model generated from the digitized image. The original boundary representation provides a template to transform the representation through processing under governance of a programmed processor so as to recover accuracy and reintroduce feature edges and feature corners as well as other detailed features to the CAD model obtained from the digitized image, e.g., to enable detailed features to be retained that would otherwise have been lost due to the lossy conversion into image space. The method operates to better ensure that reconstructed boundary vertices lie on original CAD model surfaces and feature edges and corners are recovered.