While often confusing, like anything that else that can be copyrighted, artwork is protected by copyright when the art is affixed in a tangible form (such as a painting, sculpture, or drawing). However you have to register your copyright with the US Copyright Office if you want to be able to take infringers to court and be awarded damages.
Section 102(a) of the U.S. Copyright Act states that copyright subsists in original works of authorship fixed in a tangible medium of expression. Federal copyright law protects your work upon completion of your painting and during its development over time. Registration of your work is voluntary.
The Copyright Act states that “pictorial, graphic, and sculptural works include two-dimensional and three dimensional works of fine, graphic, and applied art, photographs, prints and art reproductions, maps, globes, charts, diagrams, models, and technical drawings, including architectural plans.” (17 U.S.C. § 101)
Photographs may be registered with the U.S. Copyright Office as visual art works. The copyright in a photograph protects the photographer’s artistic choices, such as the selection of the subject matter, any positioning of subject(s), the selection of camera lens, the placement of the camera, the angle of the image, the lighting, and the timing of the picture.
Fine Art is very much the same, if not more important as many artists are recognized by a handful of images which are paintings, as well as the artistic style attributed to the artwork.