Film noise reduction by application of bayes theorem to positive/negative film
US4977521A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 25, 1988 |
| Grant date | Dec 11, 1990 |
| Priority date | — |
| Expiry date | Jul 25, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4097
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
At least one frame of a strip of photographic film is exposed to an image, and, prior to being developed, six (or so) calibration strips in a specially reserved frame on the same film are individually exposed to six predetermined calibration light sources producing six progressively increasing exposure levels spanning the exposure latitude of the film. A film layer develops a positive image in one color and a negative image in another color using positive and negative dyes, respectively. The film is scanned to determine the positive and negative dye amounts, D.sub.p and D.sub.n at each scanner pixel. The likeliest exposure value E as a function of D.sub.n and D.sub.p is determined probabilistically from six histograms obtained by scanning the six calibration patches on the film, all of the E's thus obtained being stored in a look-up table addressed by the corresponding values of D.sub.p and D.sub.n. The images recorded on the film are then scanned pixel-by-pixel, the D.sub.p and D.sub.n of each pixel addressing the look-up table to obtain the likeliest exposure value E for that pixel, which is then furnished to a printer. By thus combining the positive and negative images on the fi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.