What is the basic unit of an image?

The basic unit of an image is the lens.

1. Image is a photographic term.

1 refers to the object image formed by optical instruments such as lenses. There are real images, virtual images, positive images and inverted images. This optical image can only be fixed by photosensitive development of photosensitive materials.

2. It refers to the photosensitive substance produced by throat light, and the blood after development is basically similar to the subject. The image of black and white silver salt photosensitive material is composed of silver with different densities. Pigments are composed of various dyes. Non-silver materials are composed of various non-silver photosensitive materials with different densities or optical properties. Generally, it is quite stable and can be preserved for a long time. ?

Second, the separation of light and shade is a darkroom processing technology.

The operator can compress the continuous tone of Cafu on the black-and-white photo screen into three or four discontinuous tones. Usually, photos are made into three levels: black, medium gray and door. The production method is to copy Gao Fancha film repeatedly to obtain black and white shadow levels; Gray tone is obtained by low density exposure method, and then superimposed.

Thirdly, the contrast between light and shade is a technique of photographic modeling.

The gap between the strong light and the light on the photo screen and the number of changing stages form a contrast effect. Contains two base types.

1, tone contrast, that is, tone contrast, such as black and white contrast.

2. The contrast of tonal areas, that is, the contrast of different areas occupied by various tones in the scene. The application of tone contrast can form a strong contrast, thus highlighting the main body or a certain part of the main body of the picture. And it is easy to make the picture show intense thoughts and feelings.

Fourthly, tone compression is a darkroom processing technology.

A processing method of changing the original negative with three tones of black, white and gray continuously into pure black and pure white tones. The basic process of film reduction is: using high reflection positive film (such as positive film for printing and plate making, film positive film), contact printing and repeated copying until the middle gray adjustment part disappears.

Finally, the ratio of black and white stripes on the negative. Finally, the negative is printed on hard paper, and the photos with positive and negative tones can be obtained. According to the degree of compression, photos can show artistic effects such as woodcut and lithograph, and have the characteristics of clear white and strong contrast.