About colors About colors
The color spectrum, wavelength and color temperature



The spectrum

In 1664, while still a student, Sir Isaac Newton investigated the refraction of light by a glass prism. Developing over a few years a series of increasingly elaborate, refined, and exact experiments, Newton discovered measurable, mathematical patterns in the phenomenon of colour. He found white light to be a mixture of infinitely varied coloured rays (manifest in the rainbow and the spectrum), each ray definable by the angle through which it is refracted on entering or leaving a given transparent medium.
Color spectrum in a rainbow
Color spectrum in a rainbow.


Sir Isaac Newton discovered that ordinary white light consists of an infinite amount of colors; the colors in a rainbow.
Color spectrum of white light falling through a prism
Color spectrum of white light falling through a prism.


The electromagnetic spectrum also contains the cosmic rays, gamma rays, x-rays, ultra violet, shortwave infrared, infrared, radio waves and electromagnetic waves:
Build-up of the electromagnetic Spectrum
Build-up of the electromagnetic Spectrum.


CIE 1931

The Commission Internationale de l’Eclairage (CIE), internationally better known as International Commission on Illumination, is the international authority in the field of light, lightsources, color and colorspace. The CIE has its headquarters in Vienna, Austria. The CIE works together with the ISO orginisation and is seen by ISO as a standardization group.
The CIE 1931 color space chromaticity diagram with wavelengths in nanometers, developed in 1931, is still used today as the standard to define colors, and as a reference for other color spaces. The figure is a two-dimensional display of colors with the same intensity (brightness), according to the standard-CIE-1931-perception that is based on observations of color measurements by humans. A complete display of colors is actually three-dimensional, where the z-axis displays the brightness.
The CIE 1931 color space chromaticity diagram with wavelengths in nanometers
The CIE 1931 color space chromaticity diagram with wavelengths in nanometers.

The three-dimensional image looks like a pyramid. This color space cannot be used to show the difference between the colors. That’s why this system was further developed to the CIELAB-system.
The CIE chromaticity diagram was calculated in Excel, but as far as the colors go it is only an estimation of the true CIE standard.


Color perception

Here the color of a specific wavelength has been calculated to a RGB (Red Green Blue) value that is used by monitors to display “true color”.
Color spectrum, precision perception of color and the corresponding wavelength
Color spectrum, precision perception of color and the corresponding wavelength.

The color yellow that only has one spectral component at 580nm is created on a monitor by using additive color mixing of the colors red and green. These two colors each have their own spectral component at 645nm and 510 nm. Because both wavelengths and light production may vary between monitors the “white balance” should be set correctly.


Color wavelengths and color description
  Color and wavelength overview:

  RED
  700nm deep red - LED: some types, low brightness
  680nm pure red - LED: ultra red, hyper red, deep red
  660nm pure red - LED: ultra red, hyper red, deep red
  655nm red
  650nm red
  645nm bright red - LED: 640-650nm
  640nm bright red
  635nm ’HeNe laser’ orange-red - LED: super red: 635nm
  630nm ’HeNe laser’ orange-red - LED: HE red: 625-630nm
  625nm orange-red - LED: HE red: 625-630nm
  620nm clear orange-red

  ORANGE
  615nm reddish orange - LED: 615-617nm
  610nm pure orange - LED: 609-610-612nm
  605nm orange - LED: 605nm
  600nm amber-orange - LED: 600nm

  YELLOW
  595nm amber (warm yellow, yellow-orange)
  592nm amber (warm yellow, yellow-orange) - LED: 590-592-595nm
  590nm Natrium yellow
  585nm yellow - LED: HE Yellow,
  580nm pure yellow - LED: HE Yellow,
  575nm lemon yellow, become a little greenish

  YELLOW-GREEN
  570nm yellowish green (between yellow and green)
  565nm yellowgreen - LED: early types
  560nm yellowgreen - LED: pure green, 562nm
  555nm yellowish lime green
  550nm yellowish emerald green
  545nm emerald green
  540nm emerald green

  GREEN
  535nm pure emerald green
  530nm pure emerald green
  525nm pure green
  520nm pure green
  515nm green
  510nm greenish turquoise (RGB pure green)

  BLUE-GREEN
  505nm greenishe blue / turquoise
  500nm greenishe cyan
  495nm turquoisish, a little sky-blue

  BLUE
  490nm turquoisish, light sky-blue
  485nm bright, a little azure-blue - LED: 480-485-488nm
  480nm bright, a little azure-blue
  475nm bright, a little greenish azure-blue
  470nm bright blue with a liitle greenishe emphasis
  465nm bright blue with a liitle greenishe emphasis
  460nm bright blue
  455nm bright blue
  450nm pure blue - LED: Royal Blue

  BLUE-VIOLET
  445nm diep blue / violet-blue
  440nm diep blue / violet-blue
  435nm diep blue / violet-blue
  430nm violettish blue - LED: 626-428-430nm
  425nm violettish blue - LED: 626-428-430nm
  420nm deep violettish blue

  VIOLET
  415nm bluish-violet
  410nm violet with bluish emphasis
  405nm pure violet
  400nm deep and more twilight color violet than 405nm

  Nearly-UV
  395nm deep royal purple
  390nm deep royal purple with reddish tint
  385nm twilight purple with deep red blur
  380nm almost no longer visible purple



LED colors
Deep red (660 nm)
Deep red (660 nm)
Bright Red (635 nm)
Bright Red (635 nm)

Orange (610 nm)
Orange (610 nm)
Amber (592 nm)
Amber (592 nm)

Yellow (585 nm)
Yellow (585 nm)
Yellow-Green (565 nm)
Yellow-Green (565 nm)

Green (530 nm)
Green (530 nm)
Turquoise (505 nm)
Turquoise (505 nm)

Long-wavy Blue (470 nm)
Long-wavy Blue (470 nm)
Pure blue (Royal blue) (450 nm)
Pure blue (Royal blue) (450 nm)

Deep blue with violet accent (430 nm)
Deep blue with violet accent (430 nm)
Violet (405 nm)
Violet (405 nm)

Pink (Gan blue-emmiting chip, with a red emitting phosphor layer)
Pink (Gan blue-emmiting chip, with a red emitting phosphor layer)

Warm white (3300 K)
Warm white (3300 K)
Cool white (8000 K)
Cool white (8000 K)
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