darktable
Description: darktable is an open source photography workflow application and raw developer. It manages your digital negatives in a database, lets you view them through a zoomable lighttable, and enables you to develop raw images and enhance them.
Type: software
Pricing: Free
HiPaint
Description: HiPaint is a free and open source raster graphics editor for digital painting and photo editing. It has an intuitive user interface with customizable brushes and layers. HiPaint is lightweight, cross-platform and good for basic image manipulation tasks.
Type: software
Pricing: Open Source