Sunday, April 19, 2009

Photographic Printing

Check SpellingPhotographic printing is the process of producing a final image for viewing on paper, using chemically sensitized paper. The paper is exposed to either a negative, a transparency or slide, or a digital image file.
Photographs can be printed on color or black and white paper. Printing on black and white paper consists of four major steps, performed in a dark room or with a printing machine:
1. The image is exposed onto the paper using a contact printer or enlarger.
2. 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
3. After fixing, the photograph is cleansed using a hypo clearing agent to remove any fixer that could damage the print.
4. Prints are then chemically toned or hand colored after processing.Printing on colored paper requires the use of processing with certain propriety chemicals. The two main processes are RA-4, which is used for printing color negatives, and lifochrome, which is for printing color transparencies.
RA-4 prints are color negatives printed on RA-4 paper and produce a type-c print. They consist of three emulsion layers, each sensitive to red, green, and blue light. During processing, couplers produce cyan, magenta, and yellow dyes, to represent the true colors of the subject. The combination of all of these colors is what give a photograph its final look.
Lifochrome prints use a specialized Lifochrome paper that use the dye destruction process to produce prints from positive transparencies. The color dyes are induced onto the paper and are bleached during processing.
Aside from printing an image in a dark room using chemicals, photographers can also print photographers from a digital computer file. The artist can view his or her photographs on the computer and edit them before they decide whether or not to print them. They can then be printed using Ink jet printers or specialized photo printers. Image files can also be taken in to labs so that professionals can develop your images for you.

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