Simultaneous contrast
The simultaneous contrast (from Latin simul: at the same time, together, simultaneously; latin contra and stare: preclude) describes a phenomenon in which the human visual system in the vicinity of a color automatically performs the complementary color. This virtual color is purely physiological and has the purpose of being able to distinguish between objects more clearly even under unfavorable conditions. Other terms for the simultaneous contrast are Chevreul illusion , color illusion , contrast illusion or simultaneous contrast effect .
definition
Simultaneous contrast is a term used in physiology (biology / medicine), optics (physics) and art theory. It is a phenomenon in which our visual organ perceives the complementary color at the same time (= simultaneously!) When looking at a color in the environment . It is a purely physiological process to perceive contrasts more clearly.
The simultaneous contrast is not to be confused with the successive contrast (also after-effect or after-image). This is a phenomenon in which our visual organ, when looking at a color, gradually (= successively!) Creates an afterimage of this color in the same place on the retina in the complementary color.
description
The simultaneous contrast means that colors lying next to each other influence each other simultaneously and reciprocally. It brings about a contrast enhancement in terms of color brightness , hue and / or color saturation (color purity, color cloudiness). The strongest contrast arises when the differently colored surfaces are colored as evenly as possible (free of grain) and they are in direct contact with one another. If the color brightness changes, one speaks of light-dark simultaneous contrast, if the color tone changes, one speaks of colored simultaneous contrast. The colored simultaneous contrast is strongest when the brightness is the same. If there are differences in brightness, it weakens and disappears completely if there are greater differences in brightness. Because of this knowledge, the Impressionist painters, for example, avoided all differences in brightness, especially all strong shading, in order to preserve the luminosity of the colors. The luminosity (color saturation) increases most when complementary colors are next to each other. Conversely, there is no change in the vicinity of gray if the adjacent color is equally bright. That is why a color is placed on an equally light gray surface in order to perceive the color tone unadulterated.
Explanation
The human eye is not an optical-physical measuring instrument that objectively measures the given frequency and amount of light. Because not every rod (light-dark-perceiving receptor) or cone (color-sensitive receptor) in the retina has a separate nerve line to the brain. Rather, there are several layers of nerve cells in the retina, the fibers of which are connected to one another and to the receptors and the brain. The same (physically objectively measurable) color stimulus, i.e. the same sensation-triggering electromagnetic wave, can lead to completely different color sensations on the part of the viewer. This is a purely physiological correction process of the visual organ. The color that appears to be mixed in is a virtual color, an induced color that is not objectively present. The purpose of this process is to more clearly distinguish neighboring colored areas from one another. This is why one speaks of a contrast illusion. As a rule, it is more important to perceive contours clearly than slow intensity gradients. The boundaries of objects should be optimally detected even under unfavorable environmental conditions. For example, it is much more important for survival to distinguish a lion in the middle of the savannah than to recognize two identical shades of yellow.
Essentially, the contrast enhancement is due to the fact that each receptor in the retina does not transmit its color perception to our brain in isolation, but rather suppresses the perception of its neighboring receptors and thus creates the impression of complementary color there. In other words: "If a horizontal cell is excited by a rod or cone, it also excites neighboring receptor cells, but also inhibits bipolar cells that are further away . This mechanism causes a point of light to appear brighter than it actually is and the surroundings to be darker processing as lateral inhibition ( "lateral inhibition") is referred to, the edges of the perceived objects to be tightened and amplifies the contrast. "
Examples from color theory
Probably the simplest simultaneous contrast is the Hering contrast . It is a light-dark simultaneous contrast (also: simultaneous light-dark contrast, lightness contrast or light illusion), which only affects the lightness of colors or gray tones. The gray square appears darker in white surroundings and lighter in black, although it is the same shade of gray. The German physiologist Ewald Hering first described this contrast.
Another light-dark simultaneous contrast is called Machsche Stripes (also: Mach stripes, Mach bands, Chevreul-Mach bands, Mach contrast). Ernst Mach was an Austrian sensory physiologist. He designed a picture of stripes that get lighter and lighter from black to various shades of gray. And although every gray stripe has a homogeneous shade of gray, every shade of gray appears darker on the border to the lighter gray and lighter on the border to the darker gray. This phenomenon is also called "groove effect" or "fluted effect", as it is reminiscent of the surface of fluted Doric columns .
In addition to the light-dark simultaneous contrast, there is the colored simultaneous contrast (also: simultaneous color contrast, color contrast or color illusion). The exclusive change in color only occurs when the neighboring colors are equally bright. So a gray appears reddish in an equally lighter green environment. And a red looks particularly intense and luminous next to a green. This shows the fact that complementary colors increase each other to extreme luminosity. Usually mixed forms of hue, lightness and saturation contrasts are the rule. For example, a red next to an orange appears bluish, darker, and cloudy (less saturated). A gray appears blue-greenish and lighter in a red (darker) environment. A green appears bluish, darker and cloudy next to a yellow and lighter and more luminous (more saturated) next to a black.
Another example is intended to illustrate the mutual effect of simultaneous contrast - but in a greatly exaggerated form. The four squares in the colors red, white, black and green influence each other in the edge area. The red induces green in its surroundings. So the white at the edge appears light green and the black dark green. The white creates a black sensory impression in its surroundings. So the red at the edge becomes dark red and the green dark green.
The Bezold effect is a special form of simultaneous contrast . Normally, the gray band plaited through the colorful stripes should appear greenish on the left, since the surroundings are red. In fact, it appears reddish in color compared to the right gray band. The German professor for meteorology, Wilhelm von Bezold discovered that a color assimilates its neighboring color if small areas of color are interspersed.
Examples from everyday life
snowflakes
When the snow drifts in winter, it can be observed that the flakes in front of a milky white sky do not fall from the sky as white, but as dirty gray spots. And only in front of a dark house wall do they turn into white snow. The color change occurs suddenly and is a consequence of the simultaneous light-dark contrast.
Paints
When painting, the phenomenon often occurs that a mixture of colors looks completely different on the palette than on the canvas. In addition to a changed size, surface / structure and shape, this is primarily due to the different colored surroundings, ie the simultaneous contrast.
Complexion
The northern European complexion is often pale and not very saturated. "If a person whose skin undertone turns bluish wears, for example, an orange-colored piece of clothing, the orange pushes the color of the face into a bluish simultaneous contrast. This can create an unhealthy impression of the color of the face .... A strong blue piece of clothing would be Shift the color of the face towards orange and thus look much more beneficial. The person's charisma would be relaxed and vital. "
Tie fabric
Johannes Itten describes an incident that illustrates the effects of simultaneous contrast. "A few years ago the owner of a tie weaving mill showed me desperately a few hundred meters of the most expensive tie fabric, which was not removed because a black stripe woven on a red background did not look black but green and gave the fabric a restless vibration. This simultaneous effect was so strong that the customer claimed that the weaver had woven green thread instead of black thread. " The weaver should have used a reddish, i.e. brown-black thread to neutralize the greenish effect. Then the great financial loss would not have occurred.
Examples in art
Georges Seurat , a pointillist artist, depicts the changed colors directly due to the simultaneous contrast. For example, in his painting "A Sunday afternoon on the island of La Grande Jatte" he suddenly painted a brown tree trunk in front of the blue water in orange. The frame also receives red dots next to the green meadow and blue dots next to the orange sand. In the summer of 1885, Seurat visited Grandcamp in Normandy. There he painted the beak-like rock "Le Bec du Hoc". This was a spectacular geological feature that was greatly reduced by the bombing during World War II. In the picture you can see that the ledge on the right is shaded in dark purple. That is why Seurat painted the sea next to it lighter and slightly yellowish, although objectively it should be evenly blue. Here he illustrated the halo effect ("halo" around a dark surface), a special case of simultaneous contrast.
Josef Albers is famous for his series of images "Hommage to the Square! - Homage to the Square". All these pictures consist of three or four seemingly superimposed color squares shifted a little downwards. Despite the title, Albers was less concerned with the squares than with the effect of the colors. In addition to the seemingly relief-like spatial structure and the apparent transparency of the colored surfaces, the simultaneous contrast plays an essential role. At each color edge, the colors shift towards the complementary color. The area surrounding the red square is lighter and slightly green. The red square itself appears darker in the edge area due to the neighboring lighter red-brown. In addition, the red comes to the fore because it is particularly bright, and the reddish brown seems to be transparent over the umber brown.
history
Simultaneous contrast has been known as a phenomenon for centuries. Many artists take it into account in their painting. It was already described in more detail by Leonardo da Vinci around 1500. Exact studies followed the pure descriptions only in the 19th century. Scientifically exact investigations of the physiological relationships of the organ of vision followed. Due to the complexity of our visual organ and the diversity of the simultaneous contrast, the exact processes in humans have not yet been fully clarified.
In 1810, Johann Wolfgang von Goethe described simultaneous colored contrast. "But if you put white paper on a yellow wall, you will see it covered with a purple tone." And "he who walks on meadows with a medium brightness of the sky and sees nothing but green in front of him, [sees] often the tree trunks and paths shine with a reddish glow." Goethe describes the phenomenon as a "legal requirement" of our eyes. "If a colored picture is drawn on one part of the retina, the remaining part is immediately in a disposition to produce the [opposite] ... colors."
The French Michel Eugène Chevreul was a chemist and founder of the modern theory of colors. His work "De la Loi du Contraste Simultané des Couleurs" (On the law of the simultaneous contrast of colors) from 1839 is considered one of the most important works on color theory. Through observation, experimentation, and color demonstrations, Chevreul developed his basic law.
From 1865 the Austrian sensory physiologist Ernst Mach investigated the contrast phenomena at the borders of differently bright fields (e.g. Mach stripes, see above) and interpreted them through a spatial interaction in the retina. In 1878, the German physiologist Ewald Hering described the simultaneous color contrast. He interpreted the contrast phenomena as physiological interactions in the retina. His opponent, the German physiologist and physicist Hermann von Helmholtz, preferred a psychological interpretation as a "deception of judgment". Hering's theory could only be confirmed in our days.
The German neurophysiologist Günter Baumgartner placed microelectrodes in cats' optic nerve and recorded the electrical currents. In 1949 he realized that there are two types of ganglia cells . The ON center ganglion cells react particularly strongly when the inner area is stimulated in the receptive field, but the outer area is not. In the case of OFF-center ganglion cells, it is the other way round. The fact that signals from the edges of the receptive field can influence the information in the middle is known as lateral inhibition. The American physiologist Haidian Keffer Hartline (1903-1983) studied in 1959 the eyes of horseshoe crabs (Limulus). "Lighter on-center neurons [ON-center ganglion cells] show increased activation in lighter areas of the contrast border as a result of the lateral inhibition. 'Darker' reporting off-center neurons [OFF-center ganglion cells] become, however laterally activated at the border of the darker field by reduced central inhibition. " This neural interaction explains the simultaneous light-dark contrast.
A particular difficulty in research on simultaneous contrast (and color vision in general ) lies in the fact that the human nerve cells in the organ of vision are extremely small (just under a ten-thousandth of a centimeter). And the connecting nerve fibers are even smaller. So far there are no such fine electrodes that could be inserted as probes. Studies on animals with larger nerve cells and nerve fibers can only be transferred to humans to a limited extent due to the lack of or controversial color vision of many animals.
literature
- Günter Baumgartner among others: Seeing (sensory physiology III) . In: Human Physiology . 1st edition. Volume 13. Urban and Schwarzenberg, Munich, Vienna, Baltimore 1978.
- John P. Frisby: Vision, optical illusions, brain functions, image memory . 1st edition. Heinz Moos Verlag, Munich 1983.
- Johann Wolfgang von Goethe: On the theory of colors, the main work of 1810 . In: Goethe: Color theory . Scientific book club e. V., Tübingen 1953.
- Johannes Itten, Art of Color, Subjective Experience and Objective Recognition as Paths to Art . 4th edition. Otto Maier Verlag, Ravensburg 1961.
- Wolfgang Metzger: Laws of seeing, the doctrine of seeing the forms and things of space and movement . 3. Edition. Waldemar Kramer, Frankfurt am Main 1975.
- Friederike Wiegand: The art of seeing. A guide to image viewing . 2nd Edition. Daedalus Verlag Joachim Herbst, Münster 2019, ISBN 978-3-89126-283-2 .
Individual evidence
- ↑ Brockhaus Encyclopedia in 24 volumes . 19th edition. tape 12 and 20. PA Brockhaus, Mannheim 1993, ISBN 3-7653-1100-6 , p. 315 (volume 12) and p. 302 (volume 20) .
- ↑ For example B. Josef Albers in his book "Interaction of Color - Basics of a Didaktik des Sehens" wrongly equates the simultaneous contrast with the afterimage / successive contrast (Verlag M. DuMont Schauberg Cologne 1970, p. 48).
- ↑ See: What is simultaneous contrast. Retrieved June 25, 2019 .
- ↑ Cf. Friederike Wiegand: The art of seeing. A guide to image viewing . 2nd Edition. Daedalus Verlag Joachim Herbst, Münster 2019, ISBN 978-3-89126-283-2 , p. 148 .
- ↑ Neil A. Campbell / Jane B. Reece: Biology . 6th edition. Spectrum Academic Publishing House, Heidelberg / Berlin 2003, p. 1276 .
- ↑ See Hans Joachim Albrecht: Color as Language - Robert Delaunay - Josef Albers - Richard Paul Lohse . Verlag M. DuMont, Schauberg 1976, p. 90 u. 95 .
- ↑ The simultaneous contrast. Marks Design, accessed June 5, 2019 .
- ↑ Johannes Itten: Art of Color, Subjective Experience and Objective Recognition as Paths to Art . 4th edition. Otto Maier Verlag, Ravensburg 1961, ISBN 3-473-61550-1 , p. 88 .
- ↑ See Hans Joachim Albrecht: Color as Language - Robert Delaunay - Josef Albers - Richard Paul Lohse . Verlag M. DuMont, Schauberg 1976, p. 89 .
- ↑ Johann Wolfgang von Goethe: On the theory of colors, The main work of 1810, No. 56 and No. 59 . In: Goethe: Color theory . Scientific book club e. V., Tübingen 1953, p. 193 .
- ↑ Johann Wolfgang von Goethe: On the theory of colors, The main work of 1810, No. 56 . In: Goethe: Color theory . 1st edition. Scientific book club e. V., Tübingen 1953, p. 192 .
- ↑ Günter Baumgartner among others: Seeing (sensory physiology III) . In: OH Gauer, K. Kramer, R. Jung (Hrsg.): Physiologie des Menschen . 1st edition. tape 13 . Urban and Schwarzenberg, Munich, Vienna, Baltimore 1978, pp. 309 .