In visual perception, contrast is the difference in visual properties that makes an object (or its representation in an image) distinguishable from other objects and the background.

• In visual perception of the real world, contrast is determined by the difference in the color and brightness of the light reflected or emitted by an object and other objects within the same field of view.
• In imaging, contrast depends additionally on the image source, the medium, and the ambient lighting.

For example, in the case of graphical computer displays, contrast depends on the properties of the picture source or file and the properties of the computer display, including its variable settings. For some screens the angle between the screen surface and the observer's line of sight is also important.

In telecommunication, the term contrast has the following meanings:

1. In display systems, the relation between (a) the intensity of color, brightness, or shading of an area occupied by a display element, display group, or display image on the display surface of a display device and (b) the intensity of an area not occupied by a display elements, a display group, or a display image. Deprecated synonym: brightness ratio.
2. In optical character recognition, the difference between the color or shading of the printed material on a document and the background on which it is printed.

Source: from Federal Standard 1037C

• In music and musical form, procedures of contrast include stratification, juxtaposition, and interpolation. Procedures of connection include gradation, amalgamation, and dissolution .