To suggest detail without actually rendering it.

More sophisticated paintings suggest detail without actually rendering it. This increases the viewer’s involvement and interest in the painting by making viewers exercise their own imagination, which is almost limitless. No longer are you just showing the viewer what you, the artist, is thinking about, but you are stimulating them to contribute their own thoughts and images to the work. In this way, the viewer becomes a participant in the experience. If you depict everything as does a camera, you leave nothing up to the imagination of the viewer, who becomes just a spectator of the work, rather than a participant in it.