Why is yellow the most visible color


The subject of "colors" concerns both physics (electromagnetic spectrum) and chemistry (VIS spectroscopy, dyes, pigments). Visible light covers the spectral range from approx. 380 nm (violet) to 780 nm (dark red), in the narrower sense 400 - 700 nm, since the sensitivity of the human eye decreases sharply towards the edges. The highest sensitivity is around 550 nm (yellow-green).

A representation of the light spectrum in the range from 430 nm to 681 nm using RGB values ​​can be found on the website "The color spectrum in sRGB" (CIECAM02), an interactive website for building RGB colors is e.g. the "ColorPicker".

On websites you can display RGB colors e.g. in td elements of table lines using the attribute "bgcolor".

<td bgcolor="#ff0000">&nbsp;</td><td>#ff0000 (rot)</td>
colourRGB valueComplementary colorRGB value
 # ff0000 (red)# 00ffff (cyan, turquoise)
 # 00ff00 (light green)# ff00ff (magenta, fuchsin)
 # 0000ff (blue)# ffff00 (yellow)
 # 8000ff (purple)# 80ff00 (yellow-green)
 # 6f00ff (indigo)# 90ff00 (yellow-green)
 # ff8000 (orange)# 007fff (azure blue)
 # 00ff80 (teal)# ff0080 (purple)

Spectral colors

Prism spectrum

CD spectrum; the effect can only be explained by quantum electrodynamics (QED)

For reasons of number symbolism, one often speaks of seven spectral colors: violet, indigo, blue, green, yellow, orange, red. The highlighting of "indigo" seems a bit arbitrary, one could just as well include green-blue, cyan (turquoise), blue-green and yellow-green. All spectral colors are standardized to maximum brightness, i.e. at least one RGB component must have the value 255 (0xff). The ring closure to the color wheel is interesting: the shades of the shortest-wave purple and the longest-wave red (purple) are very similar.

Spectral colors: names, sRGB values ​​and wavelengths (CIECAM02)

coloursRGB valuewavelengthColor name
 # 8700ff430.0 nmviolet
 # 0000ff454.2 nmblue
 # 007fff459.3 nmazure
 # 00ffff490.4 nmturquoise
 # 00ff80524.6 nmturquoise green
 # 00ff00542.3 nmgreen
 # 80ff00550.9 nmyellow-green
 # ffff00571.0 nmyellow
 # ff8000597.2 nmorange
 # ff0000630.5 nmred
 # ff0028681.0 nmpurple


colourRGB valuewavelengthColor name
 # ff000c633.7 nmred
 # ff9c00590.1 nmyellow (orange)
 # 00ff9f515.2 nmgreen
 # 0080ff459.4 nmblue

Among other things, due to the lack of luminosity and the lack of contrast, the LED colors appear too dark and falsified here. In reality, red, green and blue LEDs give subjectively pure color light, yellow LEDs appear orange-yellow (and not brownish as on the screen).

Complementary colors

Complementary colors are obtained by subtracting the RGB values ​​of the colors from the maximum value 255 (0xff). Color plus complementary color as well as the mixture of red, green and blue results in white light additive Color mixing.

Non-spectral colors (mixed colors)

In principle, there are an infinite number of different colors or shades. Only part of it can be observed in the spectrum (prism spectrum, grating spectrum or rainbow). Typical non-spectral colors (mixed colors) are purple, lavender, pink and brown. From a physical point of view, white, gray and black are not colors (achromatic areas).

colourRGB valueColor name
 # ff00ffmagenta, fuchsia
 #800080purple (web color: purple)
 # 9932ccpurple, lilac-colored (web color: DarkOrchid)
 # ffc0cbpink (web color: pink)
 # a52a2abrown (web color: Brown)
 #808000olive (color: olive)
 #000080navy blue (web color: navy)
 #ffffffwhite (web color: white)
 #808080gray (web color: gray)
 #00000black (web color: Black)

Emission (spectral lines), transmission, fluorescence and remission

From a chemical point of view, colors are observed in emission (spectral lines of atoms, but also fluorescence and phosphorescence), in transmission (transmitted light) after light has passed through a colored solution or colored transparent material (glass, plastic) or in remission (reflection) Reflecting light through a colored surface (colored paper, colored textiles, leaves, flowers or fruits).

The transmission light of a colored solution or a colored transparent material shows the Complementary color of the absorption spectrum. This can approximately also be the case with the remission spectrum, but there are also special solid-state and surface effects.

Printing inks

The CMYK colors, i.e. cyan, magenta, yellow and black, are typically used as printing inks. Theoretically, the subtractive color mixture of cyan, magenta and yellow results in black, but in practice this is only "dirty".

Note: The color "cyan" was originally defined as the color of Berlin blue (Prussian blue, Turnbulls blue: iron (III) hexacyanoferrate (II)), a dark gray blue. "Magenta" was originally the name given to the color of the dye fuchsine.

colourRGB valueColor name
 # 00b7ebCyan (print cyan)
 # ff0090Magenta (print magenta)
 # ffe700Yellow (process yellow)

Opaque paints (Pelikan ink box)

The specified RGB values ​​are self-determined approximate values.

colourRGB valueColor name
 # dacb3cLemon
 # dcb923yellow
 # f1913eIndian yellow
 # c38b3aOcher yellow
 # ed7c3forange
 # d45a42Vermilion dark
 # c24f40Carmine
 # ca5179Magenta
 # af6447Brothers Siena
 # 695a3eUmber nat.
 # 7a8a3aolive green
 # 69cd66Yellow-green
 # 33ab77French green
 # 419a7fBlue green
 # 2789a0Turquoise blue
 # 4581d6Cobalt blue
 # 2d80b1Cyan blue
 # 445ba7Ultramarine blue
 #335484Prussian blue
 # 8460aeviolet
 # 3d3e3cblack
 # dcb29eFlesh color
 # d1d6d4silver
 # dbb967gold

Remarks: The color tone recorded in the digital photo is heavily dependent on the lighting conditions. "Yellow green" is actually "light green", "violet" is more purple, and "black" is dark gray. The metallic luster of the two metal colors silver and gold is hardly visible in the photo and is not present in the analyzed color (light gray or golden yellow).

Additive and subtractive color mixing

Additive color mixtures are obtained by superimposing light of different wavelengths and intensities. In principle, the three basic colors red, green and blue (RGB) are sufficient for this (color television, colored computer screens). Their RGB values ​​are obtained by adding the RGB values ​​of the components and, if necessary, normalizing them; the maximum value of a component must not exceed 255 (0xff). The RGB components may have to be scaled down proportionally.

Subtractive color mixtures are created by mixing opaque colors (pigments), e.g. in an ink box or on a palette. Red, green and blue or cyan, magenta and yellow make black.

Some subtractive color mixes

Color 1Color 2Mixed colorExplanation
   yellow and red give orange
   yellow and blue gives green *)
   red and green gives brown
   red and blue gives purple

*) Theoretically, pure blue and pure "complementary blue" (yellow as a mixed color) result in black when mixed with subtractive colors. In practice, e.g. with an ink box, you get a dirty green.

- BKi