Photographic print toning
In photography, toning is a method of altering the color of black-and-white photographs. In analog photography, it is a chemical process carried out on metal salt-based prints, such as silver prints, iron-based prints, or platinum or palladium prints. This darkroom process cannot be performed with a color photograph. The effects of this process can be emulated with software in digital photography. Sepia is considered a form of black-and-white or monochrome photography.
Color image
Grayscale image
Sepia-toned image
Color photograph
The cyanotype is a slow-reacting, economical photographic printing formulation sensitive to a limited near ultraviolet and blue light spectrum, the range 300 nm to 400 nm known as UVA radiation. It produces a monochrome, blue coloured print on a range of supports, often used for art, and for reprography in the form of blueprints. For any purpose, the process usually uses two chemicals: ferric ammonium citrate or ferric ammonium oxalate, and potassium ferricyanide, and only water to develop and fix. Announced in 1842, it is still in use.
A cyanotype of algae by 19th century botanist Anna Atkins
Sir John Herschel (1842) Experimental cyanotype of an unidentified engraving of a lady with a harp, Museum of the History of Science
Architectural drawing blueprint, Canada, 1936
Cyanotype postcard, Racine, Wis., c. 1910