opencanvas

openCanvas is a raster graphics software developed and published by PGN Corp. It was originally released as freeware in 2000, but moved to a shareware model starting with version 2. All functions are available during the limited demo period. A higher performance version "openCanvas Plus" has been released simultaneously since version 3. Its functions are similar to Adobe Photoshop or Corel Painter.

https://en.wikipedia.org/wiki/OpenCanvas
https://www.portalgraphics.net/en/oc/