Direct positive silver halide photographic material and method for forming high contrast positive image using the same
US5362621A · kind A · utility
4Cited by
2References
36Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1993 |
| Grant date | Nov 8, 1994 |
| Priority date | — |
| Expiry date | Aug 18, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C1/48523
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A direct positive silver halide photographic material and a method for forming a high contrast image using the same are disclosed, in which a pre-fogged direct positive silver halide emulsion layer contains a salt of a nitrogen-containing compound having at least one pyridine nucleus and at least one pyridinium nucleus. The photographic material, after imagewise exposure, is developed with an alkaline developer containing a developing agent, preferably a reductance compound. The photographic material provides high contrast characteristics having a gamma exceeding 10.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.