Red is the color of love, of the revolution, of myth, of royalty, of the deities, of hell, of the ban, of danger, of Christmas! Its symbolic meaning and its evocative function, have accompanied the history of man and continue to tell it!

But it's easy to say red! What are we referring to when we talk about this color?

Recall that the color of an object is determined by the wavelength of the light that is reflected from its surface. When light radiation hits an object, some wavelengths can be absorbed by the electrons of the material of which the object is made, while those not absorbed, constitute the particular color of the object. Therefore color is not a characteristic of an object, but an interpretation of our brain, of what is detected by the three types of photoreceptors, said cones, focus on the retina of the human eye.

Red is classified as “warm color”. Among the visible colors, it is the one with the lowest frequency and the longest wavelength (between 625 and 740 about nanometers). Even lower frequencies fall into the infrared.

Given that the colors depend on our perception and that this can vary from one subject to another, over time various methods have been created to make the classification objective, to define colors based on coordinates, with standardized light. In the major graphics software there are chromatic coordinates (HEX, RGB, CMYK e HSV) that allow us to better orient ourselves.
In the case of red, eg, we can distinguish: magenta, the scarlet, the vermilion, the cinnabar, the red lead, coral, cadmium, the crèmisi, il pompeiano, the purple, the carmine, amaranth, the grenade, it burgundy, the cherry, the terracotta, the Venetian, the Titian, the Valentino, the Ferrari and others.

CURIOSITY':

🔴 Red also appears in the most ancient cave paintings of about 20 thousand years ago. In the walls of the caves, animals were represented using minerals such as iron oxides and hydroxides for yellow and red and other minerals for black and white.

🔴 In the plant world, red may indicate the presence of lycopene. Examples of vegetables and red fruits are red chard, strawberries, the cherries, blood oranges, tomato.

🔴 A classification system widely used worldwide is that of Pantone. Each color has a unique identification code. Pantone recently classified the Red Period color, as part of a campaign to end the stigma associated with menstruation.

🔴The bull is unable to distinguish red because its eyes lack cones. He throws himself against the bullfighter's cloak by instinct and by the movement of the target.

🔴 Cochineal is used to produce part of the red dyes used in the food industry (the food additive E 120 is an aluminum salt of carminic acid) and, to a lesser extent, in the dyeing of fabrics. It is obtained from the carapace of the insect of the same name.

🔴 The legendary figure of Santa Claus is thought to be related to that of Saint Nicholas, bishop dressed in red. According to other stories, Santa Claus was originally dressed in green. Certainly CocaCola helped create the image of the modern Santa Claus, smiling, chubby and with a white beard! But as for the dress, before their advertising campaign, he had already been drawn in a red suit (in particular by the famous political cartoonist Thomas Nast and in a Christmas card printed by Louis Prang).

And you, what red you are?

Sources:

https://www.lescienze.it/news/2016/04/07/news/visione_colori_penombra_cellule_gangliari_bastoncelli-3043349/

https://www.iapb.it/fotorecettori-coni-e-bastoncelli/