Blue
Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal mixture of red and green light. On a colour wheel based on traditional colour theory (RYB), the complementary colour to blue is considered to be orange (based on the Munsell colour wheel).[2] The English language commonly uses “blue” to refer to any colour from navy blue to cyan. The word itself is derived from the Old French word bleu.

Bleu
Le bleu est une des trois couleurs primaires.
Il a une longueur d’onde comprise approximativement entre 446 et 520 nm.
Elle varie en luminosité du cyan à une teinte plus sombre comme le bleu de Prusse (ou bleu de minuit).
Le bleu est la couleur du ciel et de la mer.
Bleu vient de l’ancien haut-allemand « blao » = brillant.

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