Method and apparatus for optically reading pre-printed survey pages
US5101447A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 1990 |
| Grant date | Mar 31, 1992 |
| Priority date | — |
| Expiry date | Jul 6, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K17/0032
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Apparatus is provided whereby a template for a pre-printed survey page is developed and captured as a computer data file, so that a number of pre-printed pages having the same form may be analysed to determine the presence or absence of a mark in each response position found on that form. The forms are analysed by feeding them, seriatim, to a reading station where a digital image of each form is captured using one or more video cameras. The same station is used to set up the template in the first instance, whereby data determining reference frame lines, landmark and whitemark positions within the reference frame, and response positions, may all be pre-determined. A plurality of cameras may be used for each pre-printed page, each camera viewing only a small portion of the page, with the fields of the cameras overlapping to some extent. By establishing spaced apart landmarks, and establishing the absolute values for landmarks which are printed on the page and whitemarks where no mark is expected on the page, the limits of greyscale may be determined for the page whereby the presence or absence of a mark in an expected response position may then be determined. If necessary, algorithms…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.