Method of calibrating image scanning apparatus of a photographic film scanner
US6462772B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 23, 1998 |
| Grant date | Oct 8, 2002 |
| Priority date | — |
| Expiry date | Dec 23, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4076
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a photographic film digital image scanner, long term adverse effects on image scanning system response are compensated for by establishing an initial gain calibration profile in advance of commencing image scanning operation. A reference Dmin value is established at the same time, preferably from film Dmin regions associated with the bar code pattern located in the leader portion of the film. When image scanning operation is commenced, an updated Dmin value is established for the frame being scanned and the initial gain calibration profile is adjusted by multiplying the pixel-by-pixel values in the profile by the ratio of the reference Dmin over the up-dated frame-specific Dmin value. Preferably, the same image sensor photosites used to establish the reference Dmin value are used for establishing the frame-specific Dmin value and the readings are taken from Dmin regions of the film associated the bar code pattern adjacent the frame to be scanned.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.