The term 'figure and ground' simply refers to:
- The figure - the subject of interest, usually in the foreground
- The ground - the context in which the subject is located, usually the background.
We understand naturally that objects have their settings, and are able to distinguish foreground objects from background objects. Perceptual mechanisms for distinguishing which items are advancing and which others are receding include:
- Gestalt perception's 'Principle of Area'
- Gestalt perception's 'Principle of Symmetry'
- Gestalt perception's 'Principle of Segregation'
- Colour perspective
- Tonal perspective
- Perspectival sharpness
Understanding how these perceptual mechanisms work allows a compositor to play with the viewer's sense of depth, creating ambiguity through figure-ground inversions. This involves minimising the levels of realistic detail in the foreground, and increasing the activity of negative space. In practice,
- the image should be just bi-tonal - commonly, one is the black of deep shadow;
- the areas of the two tones should be as equal as possible (negating the 'Principle of Area');
- reducing foreground/background cues such as comparative brightness (tonal perspective);
- emphasising regular silhouettes towards the background / de-emphasising regular silhouettes of the foreground.
Figure-ground ambiguity is an approach to creating optical tension, increasing interest, and, to a lesser extent, delay through a degree of abstraction.
