Positive/positive printing is a photographic darkroom process in which a colour transparency - a positive film image - is used directly as the printing original to produce a positive colour print on paper, without the intermediate stage of producing a negative from the transparency that conventional negative/positive printing requires. Because both the original transparency and the final print are positive images, the process is described as positive/positive to distinguish it from the conventional negative/positive printing workflow in which a negative original is used to produce a positive print.
The positive/positive printing process is used when the original photographic material is a colour transparency - such as a 35mm slide, a medium format reversal film original, or a large format colour transparency - rather than a colour negative, and a reflection print on paper is required as the final deliverable. Because colour transparency film is the preferred capture medium of many professional photographers for its rich colour saturation, fine grain, and accurate colour rendering, the ability to produce high quality prints directly from transparencies has historically been an important capability for professional and commercial photography laboratories.
Producing a positive print from a positive transparency requires a different approach from conventional negative/positive printing, as the tonal and colour relationships of the transparency must be preserved rather than reversed in the printing process. Two principal methods have been used to achieve positive/positive colour prints from transparency originals. The first involves the use of specialist reversal colour printing papers - such as Kodak's Ektachrome paper and Fujifilm's Cibachrome, later rebranded as Ilfochrome - that are specifically formulated to produce a positive image when exposed to and processed from a positive transparency original, using an internal image reversal chemistry analogous to the reversal processing used to produce the original transparency.
Ilfochrome - originally developed and marketed by Ciba-Geigy under the Cibachrome name before passing to Ilford - became the most celebrated and widely used positive/positive colour printing material, achieving an outstanding reputation for its extraordinary colour saturation, exceptional sharpness, and remarkable archival stability. Unlike conventional colour printing papers in which the image dyes are formed during development, Ilfochrome uses an azo dye destruction process in which the full complement of image dyes is incorporated into the paper during manufacture and selectively bleached away during processing to reveal the positive image, producing prints with a purity and stability of colour that conventional dye coupler materials cannot match. The brilliance, depth, and longevity of Ilfochrome prints made them the preferred medium for fine art, exhibition, and archival colour printing from transparency originals for many years.
The second method of producing positive/positive prints involves making an internegative - an intermediate colour negative produced by copying the original transparency onto colour negative film - and then printing the internegative onto conventional colour negative printing paper using the standard negative/positive process. While this two stage approach introduces additional generations of image quality loss compared to direct positive/positive printing and requires additional time and expense, it allows the extensive and well established negative/positive printing infrastructure to be used with transparency originals, and can produce results of acceptable quality for many commercial and professional applications.
The widespread adoption of digital scanning and printing has significantly reduced the practical use of wet darkroom positive/positive printing processes, as transparencies can now be scanned to produce high quality digital files that are printed on inkjet or other digital printing systems with results that match or surpass the quality of conventional wet process positive/positive prints in most practical respects. Nevertheless, Ilfochrome printing in particular retains a devoted following among fine art photographers who value its unique visual qualities and archival characteristics.