Photographic printing

Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper. The paper is exposed to a photographic negative, a positive transparency (or slide), or a digital image file projected using an enlarger or digital exposure unit such as a LightJet or Minilab printer. Alternatively, the negative or transparency may be placed atop the paper and directly exposed, creating a contact print. Digital photographs are commonly printed on plain paper, for example by a color printer, but this is not considered "photographic printing". Following exposure, the paper is processed to reveal and make permanent the latent image.

The process consists of four major steps, performed in a photographic darkroom or within an automated photo printing machine. These steps are:


 * Exposure of the image onto the sensitized paper using a contact printer or enlarger;
 * Processing of the latent image using the following chemical process:
 * Development of the exposed image reduces the silver halide in the latent image to metallic silver;
 * Stopping development by neutralising, diluting or removing the developing chemicals;
 * Fixing the image by dissolving undeveloped silver halide from the light-sensitive emulsion:
 * Washing thoroughly to remove processing chemicals protects the finished print from fading and deterioration.

Optionally, after fixing, the print is treated with a hypo clearing agent to ensure complete removal of the fixer, which would otherwise compromise the long term stability of the image. Prints can be chemically toned or hand coloured after processing.