For images depicting a scene that includes a piece of artwork, i.e. an actual painting (noun), such as on canvas, or framed on a wall.
If a character in the image is shown engaged in the action of painting (verb), use painting instead.
When visible artwork is being actively painted, both tags are applicable.
When something is being actively painted, but the artwork is not visible, do not use this tag.
Also consider tags such as easel and canvas (object) where applicable.
For images that are actually painted by the artist, see faux traditional media instead.