We see the world in color, hence the special realism and appeal of color photography, especially since modern digital cameras shooting in color by default make it extremely accessible. Color photography not only provides us with the opportunity to more fully convey the richness of the world around us, but also imposes a great responsibility on us, making us think about the effect of color on our pictures.
How many colors are there?
Countless. The human eye is able to perceive electromagnetic radiation with a wavelength of 380 (violet) to 740 nm (red).
Spectrum visible to humans.
This range can be divided into any number of discrete colors, although any such separation will be quite arbitrary. Personally, it is most convenient for me to think in terms of the three-color scheme – RGB.
The RGB color model implies the existence of three primary colors – red (Red), green (Green) and blue (Blue), the mixture of which in various proportions and gives rise to all the variety of color shades.
This approach is justified physiologically, since the color-sensitive receptors (cones) of the retina of the human eye contain three types of photopsy: LWS (Long Wavelength Sensitive), MWS (Middle Wavelength Sensitive) and SWS (Short Wavelength Sensitive) – sensitive to red, green and blue, respectively.
Like a human eye, a digital sensor equipped with a Bayer filter (and the vast majority of them) also sees the world in three-color, forming an integral color image from red, green and blue channels. Also, the matrix of a computer monitor consists of red, green and blue subpixels.
The RGB model is called additive, because the colors in it are formed by adding primary colors to black. Mixed in equal shares, they form achromatic colors, i.e. various shades of gray. The maximum intensity on all channels gives white, and zero – black, i.e. the absence of any color.
Closing the linear spectrum, you can get a color wheel, which serves to facilitate the presentation of color transitions.
Color wheel Color wheel. Primary and complementary colors.
The color wheel is obtained when the spectrum is closed.
Colors lying against each other on the color wheel, when mixed together, as it were, neutralize each other, forming shades of gray, and are called complementary. Complementary to red is blue (more precisely, blue-green or cyan), to green is purple (raspberry, magenta), and to blue is yellow.
RGB – additive color mixing
Primary colors are mixed in an additive fashion. According to this principle, the sensor of a digital camera, a computer monitor and a person’s eye work.
It should be noted that in color printing, an image is not obtained using light, but with the help of paints applied to a surface capable of reflecting light. In this case, the brightness of the color shades no longer depends on the intensity of the light incident on the image, but on the intensity of the light reflected from it. In this regard, instead of additive mixing of the primary colors, polygraphy uses subtractive mixing of additional colors, subtracting individual spectral components from the white light falling on the paper. Obviously, subtracting the full spectrum gives a black color.
CMYK – subtractive color mixing
When printing, complementary colors are mixed in a subtractive pattern.
Color characteristics and control
The main characteristics of color are: tone (color cast), saturation, and lightness (brightness).
The tone depends, firstly, on the color of lighting, and secondly, on the color of the object itself. In other words, from how long the light waves will fall on the object, and from which of them it will reflect. Using white balance settings, we can, within certain limits, influence the color balance of the scene to achieve maximum reality, or, on the contrary, artificially shift colors to suit our artistic taste.
Control over lightness comes down to control over the amount and intensity of light. The more light, the brighter the colors, the less light, the darker they are. It is far from always possible to influence the nature of the lighting of the scene being shot, but the amount of light entering the camera’s sensor can and should be controlled. The brightness of a photograph depends on the will of the photographer and is determined primarily by exposure.
The hardest thing to control is the color saturation. For the colors in the photo to come out saturated, they must be saturated in life. If the original scene is colorless, you cannot stretch the colors in a RAW converter or Photoshop, unless you paint a dull photo manually. Yes, when the colors are beautiful, there is nothing wrong with further emphasizing their beauty and intensity (within reasonable limits, of course), but faded, boring colors cannot be turned into stunning. They can be improved a little, make them acceptable, but nothing more. Pulling Saturation to the limit, you are more likely to permanently ruin the picture.