A developable photographic latent image forms when crystals of silver halide in an emulsion layer are exposed to light.

These are essentially the same as colour negative films in that they consist of three emulsion layers, each sensitive to red, green and blue light.

When light strikes an emulsion layer, it blocks the complementary dye below it.

In these films, a single emulsion layer has panchromatic sensitivity.

Layers of dye are coated between emulsion layers to act as optical filters.

The major difference is that black-and-white film has a single emulsion layer, while most color film has three.

In addition to multiple emulsion layers, real films have other layers that are not sensitive to light.

Each emulsion layer, in addition to the light-sensitive components, contain chemicals called dye couplers.

The developer develops the silver in the emulsion layers.

This "monopack" structure is made up of three separate emulsion layers, one sensitive to red light, one to green and one to blue.