Additive synthesis

The additive synthesis is the operation consisting in combining the Lumière several transmitting sources coloured in order to obtain a news Couleur.

In additive synthesis, the primary colors generally used are three: the red , the Green and the Blue (RVB or RGB).

  • the addition of these three colors gives Blanc.
  • the absence of color gives Noir.
  • the addition two to two of these primary colors makes it possible to obtain the secondary Couleurs:
    • the red and the green give the Jaune.
    • the red and blue give the magenta .
    • blue and the green give the Cyan.

These secondary colors constitute the primary colors of the subtractive Synthèse used in printing works.

History

The law of the trichromatic synthesis said that it is possible to reproduce an unspecified feeling coloured by mixing the three primary colors. This law suggests the existence in the retina of three kinds of cells photoréceptrices sensitive to the Rouge, the Vert and the Bleu. Since 1802, Young then Helmholtz has advanced this assumption, confirmed later by various physiological and biochemical analyzes.

The additive synthesis is thus made possible by the way in which the human eye detects the color; it is not an intrinsic property of the light . Indeed, there is a great physical difference between a yellow light, wavelength 580 Nm, and a mixture of lights red and green. However, these two phenomena stimulate the cells of the eye of way similar, with the result that one does not perceive the difference.

On this subject, to also see: Three-color process, colors métamères.

Use

The additive synthesis is the principle of composition of the colors used in particular in the cathode screens, the screens LCD and the vidéoprojecteurs tri-tubes.

Certain advanced techniques of posting as the ClearType use the geometrical characteristics of the pixels to improve returned texts with the screen.

The Autochrome S of the brothers Lumière realized as of the end of the 19th century used pigments (subtractive) to recreate the light by addition of their colors. These pigments acted like coloured filters which, the catch of sight made it possible to impress a significant surface black and white only with one of the 3 primary colors, and with the examination of the photograph, to restore the color of this point of the image. The image color was thus restored by additive synthesis.

In the Years 1990, Polaroïd proposed slides colors with instantaneous development according to a similar process.

See too

Related articles

External bonds

  • Some elements of colorimetry

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