Opponent process
The opponent color theory (or the theory of colors ) also Opponententheorie is a historical theory for the perception of color in the human eye. It was published in 1874 or 1878 by Ewald Hering ( 1834-1918 ) as an alternative to the three-color theory of Thomas Young and Hermann von Helmholtz.
Herring was based on the observation that one can color impressions such as " yellowish blue ," or " reddish green " not imagine ( mutual exclusion of yellow and blue and green and red ). That's why he suspected three separate chemical processes in the retina, each with two opposite colors, each with a inhibiting and excitatory proportion who strive for a balance. The other pairs of colors are blue-yellow, red-green and black and white.
At the present state of knowledge, see color perception.
Emergence of the pairs of opposites
The knowledge of the above-mentioned pairs of opposites based on the following observations:
- In consideration of all tones appear for most people, the four colors red, green, yellow and blue as a particularly pure. Herring called these colors as unique hues. Other notes one feels always as a mixture.
- During prolonged viewing of a colored surface and subsequent observation of a neutral, light surface afterimages arise in the respective opposite color. This process is called successive contrast nowadays. The successive contrast ( successively = "successive" ) declared herring follows: In the black and white process have a perceived as a white stimulus an inhibitory effect. However, since a balance will be sought, would remain after switching the stimulus ( white), a black afterimage is caused by the dominance of the now predominant excitatory component of the process.
Look about 30 seconds exactly on the center of the square with four colors. Look then click the field with the small dot in the middle. What do you notice?
You see an afterimage of the object in complementary colors. This phenomenon could not be explained by the three-color theory.
- Colored surfaces affect the appearance of adjacent surfaces in the direction of their own complementary color (simultaneous contrast). The simultaneous contrast ( simultaneously at the same time = ) arises after herring as follows: A stimulus stimulates not only the area, which he relates, but also the neighboring regions, but in the opposite direction. Thus, for example, a very light or white area can be an object in the center of which appear black.
- One can not imagine mixing colors " yellowish blue ," or " reddish green ".
- Disturbances of color vision manifest themselves often in a loss of the ability to distinguish between blue-yellow and red - green.
Confirmation of the opponent colors theory
Although Hering's ideas were simplistic, these three processes could actually be proven. Since 1966 confirm neurophysiological research results show that there are four basic color sensations.
Three different types of cones in the eye, each for short ( blue) -, medium ( green) - and long-wavelength (red) light rays are sensitive to supply pulses to the downstream neural color channels. On the neural level, the color stimuli " connected ": red and green are subtracted, the difference is transmitted in red-green- channel; the addition of red and green on the other hand results in the perception of yellow; these impulses are relayed from subtracts blue and yellow - blue channel. All colors are also weighed against each other and combined into one signal in black and white channel (see interconnection model ). This results, as well as herring has meant three feeling dimensions: 1 Brightness, 2 yellow-blue component, 3 red-green component, from which several thousand kinds of colors can be distinguished.
Color systems based on opponent colors theory
The Hering's opponent color theory forms the basis for the " Natural Color System " used in more recent times (NCS ). Furthermore, the model of the Lab color space is based inter alia on the opponent color theory of Hering.