At the beginning of photography, many beginners, like young children, are often attracted by bright colors, but the color in photography really only raises the contrast and adjusts the saturation to the highest point. Is it so simple? When you want to do post-processing, you often see RGB, sRGB, CMYK but don't know which color mode to use. The following sections will briefly describe what the three primary colors and color spaces are, and then delve into the use of hue, lightness, and saturation in photography. With the basic concept, no matter who is playing color (photo) master!
Three primary colors and color space RGB & Color Space
Sunshine is actually a mixture of different colors of light, if Think of these shades as a systematic organization. The color space is a positioning system that describes the position of different colors in the organization. It is also a good helper for color management.
The seemingly white sun is actually a mixture of different colors, we can describe it with different color spaces.
When you use DSLR, have you ever found a color management menu? RGB and sRGB options, it looks very simple, but it is not clear what its role? When using Adobe Photoshop and other image processing software for post-production, you have been RGB, CMYK, etc. in the image & rarr; mode The strange words are scared to surrender the white flag? In fact, these nouns are different ways of describing and using color. After understanding them, you will be more familiar with the color principle behind the image!
RGB
First, we To explain “primary color”. The primary color refers to the "basic color" that cannot be obtained by blending other colors. It is not a physical concept, but rather based on the physiological effects of the human eye on light. There are two types of visual sensory cells in our eyes: cone cells and rod cells. There are three kinds of vertebral cells, which detect red, green and blue light of different wavelengths. The brain mixes and compares these three kinds of information, and then interprets them into various colors we feel; but when the night light is weak The vertebral cells will rest and change to the rod-shaped cells. The rod-shaped cells can only distinguish between light and dark, so we can't see the color. Although the vertebral cells are not the most sensitive to the red, green and blue colors, the vertebral cells of the naked eye have the largest bandwidth for the three light frequencies, and can independently stimulate the light receptors of the three colors. These three colors are considered primary colors.
RGB superimposed system schematic
CMYK
However, because the pigment uses another set of Subtractive Color System, the system is against us. It is easier to understand. In traditional pigment technology, red, yellow and blue are generally used as primary colors. When these three colors are mixed with each other, other colors are also produced. For example, yellow plus blue is equal to green, blue plus red is equal to purple and the like. The same as RGB, when the three primary colors are added together in equal proportions, it will turn gray; if the saturation of the three primary colors is adjusted to the maximum and the same amount of mixing, it will theoretically appear black, but the actual The turbid brown color appears on the top. Therefore, in the printing industry, we have added a fourth "primary color" & " — black to compensate for the lack of three primary colors; this system is called CMYK Color Space, which is Cyan ), magenta (Magenta), yellow (Yellow) and black (Black) and other four colors. We can add white to this system, but only change its saturation without changing the hue.
CMYK Declining System Schematic
HSB
Although it is rarely used in modern color management, HSB is a color space that is more in line with human physiological visual models. This mode is the Hue, Saturation, and Brightness we mentioned earlier, also known as HSL (L is Lightness, Brightness) or HSV (V is Value, Hue). HSL and HSV are transformed from RGB, both of which describe the color as a point in the cylinder. The center axis is black at the bottom, white at the top, and gray at the center. Different angles on the cylinder correspond to different hues. The distance from the surface to the axis corresponds to saturation, and the vertical distance corresponds to brightness, hue or lightness.
HSL System Schematic