Wikipedia
Krita
Krita is a raster graphics editor based on Qt 5 and the KDE Frameworks 5. Krita is designed to be a digital painting application. It has been influenced to some extent by software like Corel Painter and SAI. Krita packs with some key features different from most of its kind, including the ability to work with both bitmap and vector illustration. The developers also strive to simplify user interaction and focus on features more relevant to painting and drawing.
Krita is a free software distributed under GNU General Public License version 2 and above. It was initially released as a part of KOffice version 1.4.0, on June 21, 2005.