Due to the complexity of processing colour film (see C-41 process) and printing color photographs, and to the rise, first of Polaroid technology and later digital photography, darkrooms are decreasing in popularity.

The darkroom

The darkroom does not have to be completely dark when making black and white prints. Most black and white print papers are only sensitive to blue light, or to blue and green light, so black and white darkrooms feature a specially-made red or amber coloured light, known as a safelight. It enables the photographer to work in the light so they can see what they are doing, without exposing the paper. A low-intensity orange or yellow light can also be used, but these are less common than the red safelight. Colour print paper, on the other hand, is sensitive to all parts of the visible spectrum and therefore must be kept in complete darkness until the prints are properly fixed. There is however a very dim amber safelight that can be used in colour photography, but it is so dim as to be of little use. For both colour or black and white paper, a "paper-safe" -- a light-proof box to safely store photographic paper not in use as opposed to the boxes and light-proof bags that the paper comes packaged in -- can be used.

Another use for a darkroom is to load film in and out of cameras, development spools, or film holders, which requires complete darkness. Lacking a darkroom, a photographer can make use of a changing bag, which is a small bag with sleeved arm holes specially designed to be completely light proof and used to prepare film prior to exposure or developing.

Exposure and Development

Main article Photographic processing

The heart of most darkrooms is the enlarger, an optical apparatus similar to a slide projector that projects the image of a negative down onto a base, and finely controls the focus, amount, and duration of light. On the base, a sheet of photographic paper, typically either Resin-coated or fibre-based paper, is exposed to the enlarged image from the negative.

During exposure, values in the image can be adjusted, most often by "dodging" (reducing the amount of light to a specific area of an image by selectively blocking light to it for part or all of the exposure time) and/or "burning" (giving additional exposure to specific area of an image by exposing only it while blocking light to the rest). Filters, or thin pieces of colored plastic, can be used to increase or decrease an image's contrast, or the difference between dark tones and light tones. After exposure, the photographic printing paper (which still appears blank) is ready to be processed.

Note that some photographers who use large format (usually defined as 4x5" and larger sized film) cameras do not necessarily need to enlarge an image, but are able to produce a same sized print by placing the negative directly on top of the paper, usually pressing it down tight with glass. This is known as a contact print.