[Photography Course] Color Basis (II): Principle of Mixed Color

From the last tutorial, Photography Course Color Basis (1): Photography and color, we can know that color is actually a visual phenomenon in which light is reflected to the human eye, so color mixing is of course inseparable from light. So if you are good at physics and understand the basic principles and characteristics of light, then the principle of color mixing is easy to understand. However, most people should have lost their junior high school physics long ago, so I will talk about it in three parts. The first part mainly supplements some basic knowledge, the second part writes the principle of color and light mixing, and the third part writes the principle of pigment mixing. If you have a general understanding of the principle of color mixing, you can jump directly to the last part of the article to see my key summary.

We have probably all done prism experiments in junior high school physics class. After the white light passes through the prism, it is decomposed into chromatographic bands with gradual transition of various colors, and the colors are red, orange, yellow, green, cyan, blue and purple in turn, which is the visible spectrum. Yes, the rainbow is the dispersion phenomenon of light.

The reason why we see green leaves is that after sunlight hits the surface of leaves, green leaves absorb most of the energy of other colors, only green is reflected, and human eyes can only receive green light, so we feel green. It is the same principle to see that apples are red, because they absorb white light of other colors and reflect red light.

Now that you know the dispersion of light, it's hard to think about what would happen if you superimposed the dispersed light back. Yes, after the dispersive light is superimposed, it turns white again. When the two main monochromatic lights after dispersion (that is, the three primary colors) are superimposed, other colors of light will be produced. As you know, we see the color of pigment because some colored light in white light is absorbed. In this way, in order to facilitate understanding, I divide the light received by human eyes into three categories: reflected light, emitted light and transmitted light.

Based on these three modes, we can divide color mixing into additive mixing (color-light mixing) and subtractive mixing (pigment mixing).

Three primary colors: Also known as three primary colors, it means that none of these three colors can be mixed with the other two primary colors, while other colors can be mixed with these three colors in a certain proportion. In chromatics, these three independent colors are called three primary colors.

Three-color principle: Any color can be made by mixing three colors in different proportions. The principle of three primary colors can be explained as follows:

Classification of three primary colors: three primary colors can be divided into three primary colors of color light and three primary colors of pigment.

Intermittent color, also known as "secondary color", is a mixture of two of the three primary colors.

Complementary color The so-called complementary color of one primary color is the sum color of the other two primary colors. Among the three primary colors of color and light, the sum of red and green is yellow, the sum of green and blue is blue, and the sum of red and blue is product.

Composite color is also called "three primary colors", and the color mixed by any two intermediate colors or three primary colors is called composite color.

Color-light mixing is also called additive mixing, because any color in the formula can be generated by adding and mixing the three primary colors (red, green and blue) in different proportions, and the color and light add up to become brighter.

The three primary colors of color and light: red (R), green (G) and blue (B).

Red, green and blue light cannot be decomposed, so they are called "three primary colors", so red (R), green (G) and blue (B) are regarded as the three primary colors of colored light. Most of the colors in the visible spectrum can be composed of three primary colors in different proportions, and the three primary colors of color light are widely used in TV sets, displays and other products that emit light actively.

If red, green and blue light are mixed according to different energy ratios, we can get various colors of light, which will make human eyes have various colors of vision. If we mix red, green and blue light with the same energy, we can get white light, which is the white metamerism with continuous spectrum. This is the case with color synthesis of color TV pictures.

Color-light mixing formula:

Pigment mixing is also called subtractive mixing, because subtractive mixing forms different colors by absorbing different proportions of three primary colors, and the pigments add up to darken.

The three primary colors of pigments: cyan, magenta and yellow.

Because the pigment itself does not emit light, we see that the color of the pigment is a part of the colored light reflected by the pigment after the light source irradiates it. Therefore, the three primary colors of pigment are the extension of the principle of color-light mixing and the subtraction of color-light, so it is also called subtraction of three primary colors. Cyan, magenta and yellow pigments can produce other colors when mixed in pairs, so cyan, magenta and yellow are called the three primary colors of pigments. The mixing of three primary colors of pigments has been widely used in painting and printing.

We can explain the principle of pigment mixing from the above picture I made:

Pigment mixing formula:

Since it is the key point, it should be streamlined! I want to summarize this part with the following picture I made:

Tell you quietly, you don't have to remember so many formulas and theories. Remember the picture below, and the principle of color mixing is OK.

In the picture above, the color and light are mixed on the left. I made the mixed background of color and light black because of the mixed color and light, so you can imagine it as the effect of three beams of light (red, green and blue) shining on the wall in a dark room. The picture on the right shows pigment mixing, not subtractive mixing. You can imagine that it is produced by painting on white paper with three kinds of paint pens (cyan, yellow and magenta).

The color of each circle in the picture represents the primary color, the color where two circles intersect is the middle color, and the color opposite to the color of the circle is its complementary color.

The reason why the principle of color mixing is the second part of the basic course of color is because these two articles can be understood without knowing Photoshop at all. If you know Photoshop, you can practice the principle of color matching by yourself. By the way, in Photoshop, the color-light mixing mode is superposition, and the pigment mixing mode is positive superposition. The picture below is a picture of the layer and overlay mode made by ps.