Method to extend the linear range of images captured on film
US5134573A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1991 |
| Grant date | Jul 28, 1992 |
| Priority date | — |
| Expiry date | Nov 12, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4072
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
This invention relates to a method for increasing the range of values representing a color image which exhibit a linear response. To increase the linear range, look-up tables are formed which straighten the toe and shoulder regions of film's three density vs log exposure curves up to a prescribed limit. The values of the minimum densities for the piece of film containing the image are determined. The representative values of the image are then aligned with the input values of the look-up tables by a relative shift of the image values and the table values so that the minimum density values of the image equal the minimum density values in the look-up tables. The color density image is then processed through the look-up tables to increase its linear range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.