One of the great art forms in photography is the Duotone.
A Duotone is a half-tone reproduction of an image, using the superimposition of one contrasting colour halftone, (traditionally black), over another colour half-tone. This is most often used to highlight middle tones and image highlights. The most common colors used are blue, yellow, browns and reds.
Duotones evolved from Cyanotypes. A Cyanotype is a photographic process that results in a cyan blue print. The process was popular in engineering circles well into the 20th century. This simple and low-cost process enabled engineers to produce large-scale copies of their work, referred to as blueprints.
The English scientist and astronomer, Sir John Herschel discovered this procedure in 1842. Herschel was credited with the discovery of the Cyanotype process, but the use of the technique in photography was attributed to Anna Atkins. She created a limited series of Cyanotype books that documented ferns and other plant life. By using this process, Anna Atkins is regarded as the first female photographer.
In a typical procedure, equal volumes of an 8% (w/v) solution of potassium ferricyanide and a 20% solution of ferric ammonium citrate are mixed. This mildly photosensitive solution is then applied to a receptive surface (such as paper or cloth) and allowed to dry in a dark place. Cyanotypes can be printed on any surface capable of soaking up the iron solution.
Although watercolour paper is a preferred medium, cotton, wool and even gelatin sizing on non porous surfaces have been used. Care should be taken to avoid alkaline-buffered papers which will cause degradation of the image over time.
I created this Duotone in Photoshop which is a lot quicker and easier. To create my Blue Marilyn, I used Duotone colour mode in Adobe’s Photoshop and applied blue as a second colour over a black & white image. The imaging process computes the highlights and middle tones in the black and white image and superimposes the blue.
I have put the image in a frame to try and bring out the flavour of the Duotone. This image had very strong blacks so the blue may not be as prevalent as a proper Duotone but I like the subtle use of black and blue tones.
If you have any comments on the image or the article, please let me know. My name is Steve Howard. You have been reading the digital circus.