1)   Outliner 2.0
It gives a user the easiest way to get image contouring with desired quality. This plug-in just picks out various edges making them more expressive. ImageSkill Ouliner is FREEWARE.

 2)   XnView 1.74
XnView is a fast multi-format graphics browser, viewer, and converter. It reads more than 400 file formats. Its main features are batch conversion, image processing with many filters and effects, slide shows, twain support, and foto galleries on CD.