PhotoFiltre is a complete image retouching program. It allows you to do simple or advanced adjustments to an image and apply a vast range of filters on it. It is simple and intuitive to use, and has an easy learning curve. The toolbar, giving you access to the standard filters with just a few clicks, gives PhotoFiltre a robust look.
PhotoFiltre is free for a private, non commercial or educational use (including non-profit organizations).
In this case, registration is not necessary. But commercial or professional use requires a registration.