From the developer: "Change image perspective by specifying where any four points should move to when distorting the image. One application is to distort an aerial photograph so that all features exactly match the locations of the same features as they appear on a map - simply by positioning a marker over four features, such as houses or road crossings, which appear on both photo and map. The flexibility of this approach means you can stay with pure perspective effects or easily go beyond these to generate 'super-perspective' effects which can include image curvature. Several non-perspective distortions are available, including turning an image into a complex fractal-like form. Facilities are provided for easy generation of very high quality transformed images."