When an artist creates an impression of space within a painting, the picture plane is the transparent division between this fictive internal space and the real space outside, in which the viewer is placed. In traditional illusionistic painting using perspective, the picture plane can be thought of as the glass of the notional window through which the viewer looks into the representation of reality that lies beyond.

The picture plane helps the viewer to break the image before him into shapes in order to recreate it in his mind as well as view, appreciate and evaluate it in an orderly, efficient and pleasurable manner. In practice, the picture plane is the same as the actual physical surface of the painting.