| 摘要 |
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 may be changed for broader searches at each response position to determine whether or not a response is made at that position.
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