LazPaint is an open source image editor and paint tool.

The program has a lot of features, but doesn't present them very well, at least initially. A couple of toolbars are packed with icons so tiny that you'll need good eyesight to figure out what they mean (fortunately you do get tooltips).

Explore for a while and LazPaint becomes more impressive. There's PSD import, some powerful selection tools, configurable brushes, layer support, a wide range of blur tools, and plenty of colour adjustments.

There are also plenty of smaller surprises scattered around, from the ability to import 3D (Wavefront) objects, to the long list of resize algorithms, and the "quality" slider when saving JPEGs (just drag to see how different quality settings affect the image and its file size).

But we also noticed plenty of gaps in functionality, some significant. There's no RAW file support; very basic brightness and contrast adjustments; minimal control over sharpening, and no save to PSD.