What is "negative over, positive under" in photography? Can you explain what is a negative and what is a positive.

A negative film is an image obtained after exposure and development. Its light and shade are opposite to the subject, and its color is the complementary color of the subject. It needs to be printed on the photo before it can be restored to the positive image. .

Color positives are used to print color projection copies (movies, slide shows). The characteristics are: high contrast, low haze, high definition, and low sensitivity (and the slides and actual effects are mirrored left and right)

The above is taken from Baidu Encyclopedia, forgive me for being lazy.

.

The characteristics of negative film and positive film are opposite. The longer the negative film is exposed, the darker the color, while the longer the positive film is exposed, the lighter the color.

The negative film is overexposed. If it is a little, the color will be thicker, and it is easier for the printing shop to adjust the color. But in the actual photo you get, you may not be able to see much difference, or even not at all. If the positive photo is underexposed by half a stop, there will be a very obvious difference. Not only will the color be darker, The thicker the image, the details will be clearer. But the dark parts will be slightly sacrificed.

Over refers to overexposure, and under refers to underexposure.