Create
Use the Create option to create control points in an existing Pexel file. Until you use this option to create the control points the Pexel file consists only of the image. Images are converted to Pexel files through one of the options under File > Convert.
The format of the Pexel file name is <name>.pexel. The file should be in your current working directory. Control points consist of two components; first a real-world coordinate specifying its location on the triangulation and secondly a normalised image coordinate specifying its location on the image, i.e. X and Y values are in the 0-1 range.