Gray scale optical mark reader
US6970267B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 8, 2002 |
| Grant date | Nov 29, 2005 |
| Priority date | — |
| Expiry date | Nov 15, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V10/225
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a broad aspect of the invention, the master printed form is scanned and processed according to a forms definition program to produce a virtual form file comprising a virtual layout of the significant regions such as bubble targets of printed material on the form, on a virtual coordinate system. Production forms that have been marked by subjects (e.g., students, voters, survey respondents, etc.), are then scanned to produce a marked form file of gray scale darkness values for each marked form. The marked form file and the virtual form file, are compared and processed to determine the location and spatial relationships of the marks on the marked form, in relation to the virtual coordinate system of the virtual form. The raw scan of each marked form is also processed to determine whether darkened areas on the marked form image should be interpreted as intentional responses from the subject, at the virtual coordinates where targets are located on the virtual form.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.