Direct positive process
In photography , the direct positive process is a process in which a positive is generated without going through a negative .
With direct positive, the effect of light leads to a lightening of the photo material. In the classic negative process, however, the effect of light leads to a blackening of the film material.
Direct positives represent unique items .
Sham positive
In contrast to the direct positive, the positive image effect is achieved with a false positive by applying the negative to a dark background. Due to the dark field principle , the negative appears as a positive against a dark background .
Procedure
The first direct positive process was described by Hippolyte Bayard as early as 1840 . His process worked with silver salts. The pellet process, a further development of the cyanotype , works on the basis of iron salts.
Some of today's processes such as the Ilfochrome Classic are also referred to as direct positive processes; they serve the making of prints from transparencies and reflective originals ; A colored and positive image of the original is created with special photo material. A black and white direct positive paper has also been available from Ilford since 2010.
Sham positive process
The most important classic sham positive procedures are:
Direct positive process
The most important direct positive procedures are: