Thomas Niemann provided free calibration profiles for a very large number of cameras and lenses until April 2006. Since that date, a license for the use of the data which gives constants for a very large number of cameras, and focal lengths is required if access is needed to the latest types. Without a license, only those cameras and lenses formerly contained in the free ascii calibration profiles or those made by the user can be accessed.
Thomas Niemann, the author of PTLens, graciously provided the source code for his Photoshop plug-in, the study of which made it possible to revise the first version of the programme in Delphi 7. He also patiently tested the programme during its many development phases and provided invaluable advice as well as test data. In addition, he kindly tested version 2 which uses his new format for camera and lens profiles and offered many helpful suggestions.