J-F Niceron’s well known work on the mathematics of anamorphism La Perspective Curieuse is a much quoted but perhaps less read classic. In particular the templates he provides for various transformations are commonly used as a starting point by those artists who occasionally practise the anamorphic art. Some of these templates are known to be approximations and some are exact. In the process of casting the mathematical descriptions of these templates into modern notation suitable for computation, a peculiar error has been found in Niceron’s analysis of transformations onto the surface of a cone or pyramid. The correct relationships are presented and possible reasons for the error are discussed.