Hue, purity and lightness are the elements of color.

Brightness:

The lightness and darkness of a color are called lightness. The change of brightness can be identified by color matching, usually white. You can also check the gray scale test card. However, it cannot be said that a color has low brightness alone, and it can only be judged in the corresponding color. Colors are divided into colored and achromatic colors. The lightness and darkness of each color have corresponding positions on the gray scale test card, and so do achromatic colors.

Tone:

Color is the feeling produced by the reflection of physical light on human visual nerve. Different colors are determined by different wavelengths of light. As hue, it refers to the case of these colors with different wavelengths. The longest wavelength is red and the shortest wavelength is purple. Therefore, the colors of yellow, green and blue between red and purple and the colors of yellow, red, yellow, green, blue and purple between them are all counted as 10 color phase rings.

Purity:

Usually, the brightness or vividness of a color is called purity. All colors have purity values, and the purity value of achromatic colors is 0. Purity varies with hue, even if it is the same hue, purity will vary with lightness.

Color psychology:

Because of the visual stimulation of color, the association of life experience and environmental things in thinking is the psychological feeling of color. In fact, it is the feeling of the color you see. Colors can be divided into warm colors and cool colors. Red, yellow, orange and other colors give people strong visual stimulation, reminiscent of warm sun and fire, and make people feel warm, so they are called warm colors. Cyan and blue make people think of the sky, rivers and cloudy days and feel cold, so they are called cool colors. Warm colors have a sense of excitement and progress, while cool colors have a sense of calmness. In short, it depends on your feelings.