high contrast image of good resolution. This type
of developer can be used in automated processing
machines with replenishment.
Lith films are processed in lith developers (e.g.,
Kodak D–85), consisting of hydroquinone as the
sole developing agent, a small amount of free
sulfite, a bromide, and an alkaline agent. The
free sulfite level is often maintained by a sodium
formaldehyde bisulfite system. In lith developers,
well exposed grains in the emulsion are developed
first. Chemical reaction products of this develop-
ment influence the subsequent development of
nearby grains in two ways: the products enhance
development of well exposed grains, and they sup-
press that of poorly exposed grains. This autoca-
talytic mechanism enhances the image contrast
and contributes to the very sharply edged halftone
dots, called hard dots. One peculiarity of lith
development is that, unlike conventional develop-
ment, the contrast peaks at certain development
times and further development will lower contrast
and degrade the dot quality. Also, lith develop-
ment tends to render fine clear lines to be filled in,
and for black lines to be broadened, distorting
fine details of the originals, thereby making it
unsuitable for line type applications.
One major shortcoming of the classic lith
development is the instability and short life of
the working developer solution. Development is
manually performed in trays, and factors such as
agitation can significantly alter the results. There-
fore, newer generations of lith films were de-
signed for new types of lith developers. They use
nucleating agents and nucleating accelerators in
films and developers so that extremely high con-
trasts and lith effects are obtained with more
stable processing chemistry. In this type of sys-
tem, interaction between neighboring grains are
stronger than in classic lith development in the
sense that the development products can render
unexposed nearby grains developable, called
infectious development.
Another kind of high contrast photography is
used for scientific imaging such as microscope
photography. Techniques vary widely among re-
searchers, from high contrast technical films
developed in medium contrast developers (e.g.,
Kodak Technical Pan processed in HC-110) to
low contrast pictorial films developed in high
contrast developers (e.g., Ilford HP5 Plus pro-
cessed in D–19). Higher contrast is desired in
these applications because the original speci-
mens are often of low contrasts. The resulting
images are of continuous tone nature with
enhanced details.
Some photographers use high contrast technical
or document films to record continuous tone pic-
torial images. Such films are developed in ex-
tremely low contrast developers (such as Kodak
Technidol Liquid and POTA formula) to produce
negatives of pictorial quality. These techniques
offer higher resolution but often with inferior
tonal rendition than those obtained with pictorial
materials, especially with subjects of wide lumi-
nance ranges. As described above, there are many
different products for high contrast imaging. Such
a range of products attain desired contrasts and
other photographic properties by a variety of tech-
niques in formulation of emulsion and the proces-
sing chemicals. The photographic properties of
these films vary greatly when processed in low
contrast developers for pictorial applications.
RYUJISUZUKI
Seealso:Camera: An Overview: Developing Pro-
cesses; FilmFurther Reading
Bruno, M. H. ‘‘Imaging for graphic arts.’’ InImaging Pro-
cesses and Materials. Edited by Sturge, J., Walworth, V.,
and Shepp, A. New York: Van Nostrand Reinhold,
1989.
Haist, G.Modern Photographic Processing. vol. 1, New
York: John Wiley and Sons, 1979; 484–507.
Lazaridis, C. N. ‘‘Hydroquinone oxidation in lithographic
developers.’’Photographic Science and Engineering 20
(1976) 20–23.
Yamada, K., Kawato, K., Hirano, S. and Katoh, K. ‘‘The
development of new nucleating agents for the low-pH
graphic arts system.’’Journal of Imaging Science and
Technology43 (1999) 103–110.
Yule, J. A. C. ‘‘Formaldehyde-hydroquinone developers
and infectious development.’’Journal of the Franklin
Institute239 (1945) 221–230.
Zwicky, H. ‘‘The mechanism of lith development.’’The
Journal of Photographic Science33 (1985) 36–40.FILM: HIGH-CONTRAST