Absolute Beginner's Guide to Digital Photography

Three Image Layers Create Color

Images

A color photograph begins as three superimposed

layers of light-sensitive silver halide emulsion cap-

turing the image. The layers are like the emulsions

in black-and-white film, except that each layer

responds only to one primary color: red, green, or

blue. Additional layers are added to improve the

color response of the three basic layers.

Film Development Process

The two most popular forms of film are slide film

and color negative film. Both forms of film rely on

the subtractive process to create a reproduction of

an image. This subtractive process comes into play

during development, which occurs in several steps.

Slide film and color negative film are sensitive to

red, green, and blue, but the end product is their

complementary colors cyan, magenta, and yellow.

The following steps walk through this transforma-

tion process during the development of color negative film:

1. Color negative film contains three layers of emulsion. Each layer is sensitive
   to one color: red, green, or blue. During exposure, an invisible latent image
   forms in each layer where light strikes the film.


2. When a color negative is developed, the exposed light-sensitive silver halides
   in each layer are converted into a metallic silver negative. At the same time,
   the developer oxidizes and combines with the dye-forming chemicals built

CHAPTER 20 COLOR THEORY 295

FIGURE 20.3
Subtractive
process.

Cyan

Magenta

Ye llow

Color films are either

positive (reversal) or nega-

tive. Reversal films create images

that can be viewed directly, such

as color slides. The images in neg-

ative films (color and black-and-

white) must be printed to be

viewed. Almost all reversal films

are developed with Kodak’s E-6

process. Color negative films are

developed with Kodak’s C-41

process.