Color wheel and color stereo based color conversion method

The colors on the color wheel that are 180 degrees apart are complementary colors, also called complementary colors. That is, each color on the color wheel has a color that is in a complementary relationship with it on the opposite side of the color wheel. Their connection lines pass through the center of the color wheel.

Inverting means changing a color to its complementary color. There are many colors on an image. Each color is converted to its own complementary color. This is equivalent to rotating the hue of the image 180 degrees. The original black color turns white. The original green color turns purple. Negative photography works on this principle.

The color has its own brightness property. For black-and-white film, under certain intensity of light, the high-bright color reflects strong light. This light hits the film and causes a strong chemical reaction, and the film is black. On the contrary, the lightness of the color is low. The light is weak and the chemical reaction on the film is weak and the film is whiter. The process of photoreduction of film negatives is equivalent to the process of reversing nature.

The film is reverted to normal black and white photos by printing paper, which is another process of film reversal. When a certain intensity of light passes through the film, the surface layer of the paper prints a corresponding chemical reaction, and the bright part of the film has a strong light transmittance. The chemical reaction on the paper is strong and this area is bright; on the other hand, the film is dark. The local light transmittance is small, the chemical reaction on the photo paper is weak, this place is dark, the different brightness on the negative film determines the different chemical reaction intensity on the photo paper, and also get different brightness, these brightness differences in shooting There is a one-to-one correspondence between the brightness of the scenes in the photo, so the landscape from nature is seen on photo paper.

Color Photo Sensitization - The restoration process is similar to black and white photographs. The difference is that the color negative film first forms the complementary color of the received light color on the negative film, and is restored through the printing phase to obtain the color that is in accordance with the nature.

Source: Photoshop Column