METHOD AND APPARATUS FOR OPTICALLY READING PRE-PRINTED SURVEY PAGES

摘要

METHOD AND APPARATUS FOR OPTICALLY READING PRE-PRINTEDSURVEY PAGESABSTRACT OF THE DISCLOSUREApparatus is provided whereby a template for a pre-printed survey page is developed and captured as a computerdata file, so that a number of pre-printed pages having thesame form may be analysed to determine the presence orabsence of a mark in each response position found on thatform. The forms are analysed by feeding them, seriatim, to areading station where a digital image of each form iscaptured using one or more video cameras. The same stationis used to set up the template in the first instance, wherebydata determining reference frame lines, landmark andwhitemark positions within the reference frame, and responsepositions, may all be pre-determined. A plurality of camerasmay be used for each pre-printed page, each camera viewingonly a small portion of the page, with the fields of thecameras overlapping to some extent. By establishing spacedapart landmarks, and establishing the absolute values forlandmarks which are printed on the page and whitemarks whereno mark is expected on the page, the limits of greyscale maybe determined for the page whereby the presence or absence ofa mark in an expected response position may then bedetermined. If necessary, algorithms may be changed forbroader searches at each response position to determinewhether or not a response is made at that position.