Contrast vision is the visual process of perceiving the difference in brightness (luminance) or colour between two objects, or between an object and its surroundings. To be able to see an object, it needs a sufficiently high contrast to its surroundings. This should ideally be at least 2:1. The lower the contrast, the more difficult it is to distinguish between two shapes.
Contrast vision is a function of vision closely related to visual acuity. Both functions, however, are not identical: contrast vision allows us to distinguish objects from each other to perceive them. Visual acuity on the other hand refers to how well we can recognize contours and details.
Significant differentiation can be recognized with a brightness contrast of 1:10 between the surroundings and the accenting. A very dramatic atmosphere is thus created. Light and shadow characterize this intense accent lighting.
The differentiation can no longer be clearly recognized if the brightness contrast between the surroundings and accenting is approximately 1:5. The attention of the observer is no longer so high.
No hierarchy can be recognized anymore with a 1:2 difference in brightness between the surroundings and the object. The room thus looks monotonous.
The objects and the wall are given general lighting by wallwashers. Beams from individual spotlights add emphasis to the objects. A higher brightness contrast increases the level of accentuation.
When the brightness contrast of the ambient surroundings to the object is 1:2, a contrast can hardly be noticed. When the ratio is 1:5, a minimum brightness contrast is established between primary and secondary points of interest. A contrast of 1:10 brings out the difference very well. A brightness contrast of 1:100 detaches the object very strongly from its ambient surroundings but an unintentional dissection of the wall can arise.
Danubiana Meulensteen Art Museum, Bratislava
The Feuerle Collection, Berlin
CEA Design Showroom, Milan
Shanghai Bund
Milan Cathedral
| Type of visual task | Contrast rendering | CRF level | CRF mean value | CRF minimum |
|---|---|---|---|---|
| mainly glossy materials, e.g. with graphic works | high | 1 | 1.0 < CRF | > 0.95 |
| Satin matt materials, e.g. in offices and schools |
medium | 2 | 0.85 < CRF < 1.0 | > 0.7 |
| Work with matt material | low | 2 | 0.7 < CRF < 0.85 | > 0.5 |
Winter sports people, especially skiers, are familiar with whiteout and they colloquially call it 'snow blindness'. Ground covered in snow, a bright horizon or snowfall can make it difficult or impossible to see your own surroundings. This is where contrast vision no longer functions.
