Page "Film stock" Paragraph 25

Development chemicals applied to an appropriate film can produce either a positive ( showing the same densities and colors as the subject ) or negative image ( with dark highlights, light shadows, and, in principle, complementary colors ).

The first films were darkened by light: negative films.

Later films that produce a positive image became known as reversal films ; processed transparent film of this type can be projected onto a screen.

Negative images need to be transferred onto photographic paper or other substrate which reverses the image again, producing a final positive image.

Creating a positive image from a negative film can also be done by scanning the negative to create a computer file which can then be reversed by software.