How to use contrast color in color matching of painting and photography?

For the convenience of the following description, RGB and CMY represent red, green, blue and cyan respectively.

The problem is that the red, green and blue of pigment are not the red, green and blue in color light. RGB mode is completely based on the eye's sensitivity to electromagnetic waves, and its basis is the frequency of light waves and electromagnetic waves. RGB and its mixed colors can correspond to a certain frequency and can be quantized. You can understand the definitions of black body and color temperature.

And RGB in art is a vague concept and a perceptual description. R is not pure red but contains a little blue, similar to rose red, while B is actually similar to indigo, containing green and so on, because pigment is a chemical substance, and its essence is atoms of various similar objects. The absorption spectrum of materials is determined by the energy levels of electrons, which are quantized, not continuous, so pigments can't be completely mixed with colors corresponding to colored light. Therefore, the complementary color of pigment and the complementary color of color light cannot be confused at all. As for the essence of complementary color mentioned in art, I have not studied it professionally, and it should belong to contrast color. It's just that the contrast between two different colors is a kind of perceptual cognition, and it's impossible to quantify modeling.

You should know that the color of the pigment and the object itself does not emit light, so its color is actually reflected by absorbing some electromagnetic waves from the light source, and then mixed with other "unwanted" electromagnetic waves and injected into the eyes or cameras (electrons jump and energy is converted after atoms absorb electromagnetic energy). Therefore, the mixing method of pigments is subtraction, and the eyes and camera are addition. In PS, two slides are inserted in front of the lens of the slide projector, and the light emitted by the light bulb is absorbed twice and projected onto the screen. This mode is subtraction. Color filtering is a method of adding color by simulating the overlapping of two films projected by two slide projectors on the screen.

In RGB additive mode, the complementary color of R is C, and C=G+B, so the complementary color of R is actually a mixture of the other two colors, and so are other relations. Different combinations of RGB produce three mixed colors of CMY. Because it is additive mode, complementary colors become white when mixed together.

Mixed mode of PS: color filter analog addition mode

In the pigment subtraction mode, the white full-spectrum electromagnetic wave is absorbed by the material, and the remaining color light is mixed to form color. The three primary colors of art are not RGB, but CMY. Although they are not true color light CMY, they can only be said to be close, as discussed earlier. In addition, due to the different processes of different manufacturers, the colors of pigments are slightly different, but for the convenience of discussion, we will assume that their proportions are idealized.

Cyan pigment is because it absorbs R, reflects G and B, and is expressed by the formula C=RGB-R=GB.

The color of pigment is because it absorbs G, reflects R and B, and is expressed by the formula M=RGB-G=RB.

Yellow pigment is because it absorbs B, reflects R and G, and is expressed by the formula Y=RGB-B=RG.

Therefore, we can see that the color of pigment is the result of additive method after subtractive method, and the complementary colors of pigment will turn black when mixed together. Because the pigment can't reach the standard color in reality, the mixed black is impure, but close to dark brown, so the printing and printing neighborhood use CMYK mode, and K stands for black pigment. And RGB in the pigment is a mixed color.

Mixed mode of PS: negative stack analog subtraction mode

It can be seen that the three primary colors in the two modes are just complementary, because their working modes are just the opposite. In additive method, RGB is mixed with CMY, while in subtractive method (pigment), CMY is mixed with RGB. Therefore, if strictly speaking, complementary colors are consistent, they are all described according to the color wheel. In photography, YB axis is called color temperature axis and GM axis is called hue axis. In fact, both ends of the axis passing through the central white point on the color wheel are complementary colors, as long as the color difference is 180 degrees.

Whether it is color light or pigment, the description of complementary colors should be unified. The red-green complementarity you mentioned should belong to the artistic contrast color, and the complementary color is the most extreme color contrast with quantifiable attributes. As for color matching, it is entirely a psychological factor. Different people don't have a fixed pattern, otherwise it is not called art. The same photo, different color matching feels completely different. You can't say which is better. It's totally subjective. It still depends on what you want.