About complementary colors in an image

Quick answer：

Complementary colors are pairs of colors that, when combined, cancel each other out to form a grayscale color. In the context of an image, complementary colors are often used to create contrast or emphasize certain elements. This concept is based on the color wheel, where opposite colors are placed directly across from each other. Examples of complementary color pairs include red and green, blue and orange, and yellow and purple.