What is the spectrum of colors and what are the three primary colors?

The spectrum color is the color of the colored light in the spectrum, that is, the red light, orange light, yellow light, green light, cyan light, blue light, purple light and other colors that are decomposed by the sun using a prism (with dispersion effect). The so-called spectrum is a continuous spectrum composed of visible light red, orange, yellow, green, cyan, blue, and purple according to their different wavelengths from the longest (760 nanometers) to the shortest (380 nanometers). Spectral color is the purest and most vivid color, and it is the reference color for color measurement. The colors of the reflected light from the scene are not spectral colors. The color of the image displayed by the color film and photo paper used in contemporary photography is far less pure and bright than the spectral color, and both contain traces of ash.

Three primary colors, also known as three primary colors. Add equal amounts to become three kinds of white. This refers to the three light colors of red, green and blue in the spectral colors. Because the three colors of red, green and blue are mixed in different proportions, other colors in the spectrum can be obtained, so red, green and blue are called the three primary colors. One of the three primary colors cannot be synthesized from the other two. The theory of three primary colors of vision is the theoretical basis of color photography, color film, and color television.

In color photography, the three primary colors of red, green, and blue are called R, G, and B respectively. The two primary colors are added to form a secondary color. For example, red and green are mixed into yellow in equal amounts, and different amounts are mixed into orange (more red and less green). In the spectrum, orange light and yellow light are between red light and green light, cyan light is between green light and blue light, and violet light is between blue light and red light, so orange, yellow, cyan, and purple are called "intermediate colors". 

Any two of the three primary colors can be mixed into countless colors in different proportions. The two colors add up to become a complex color. Any two of the countless kinds of colors can be mixed into countless kinds of complex colors in different proportions. The sum of primary colors, secondary colors and complex colors constitute the colors of nature.

The three primary colors add up equally to become white. In the field of photography, the three primary colors of color light are red, green, and blue; in the field of painting, the three primary colors of color materials are red, yellow, and blue.