Optical scan voting system

An optical scan voting system is an electronic voting system and uses an optical scanner to read marked paper ballots and tally the results.

While mark sense technology dates back to the 1930s and optical mark recognition dates to the 1950s, these technologies were first explored in the context of standardized tests such as college entrance exams. The first suggestion to use mark sense technology to count ballots came in 1953, but practical optical scanners did not emerge until the 1960s. The Norden Electronic Vote Tallying System was the first to be deployed, but it required the use of special ink to mark the ballot. The Votronic, from 1965, was the first optical mark vote tabulator able to sense marks made with a graphite pencil.

The oldest optical-scan voting systems scan ballots using optical mark recognition scanners. Voters mark their choice in a voting response location, usually filling a rectangle, circle or oval, or by completing an arrow. Various mark-sense voting systems have used a variety of different approaches to determining what marks are counted as votes. Early systems, such as the Votronic, introduced in 1965, had a single photosensor per column of marks on the ballot. Most such tabulators used analog comparators that counted all marks darker than a fixed threshold as being votes. The Optech line of scanners developed by Business Records Corporation and sold by both Election Systems & Software and Sequoia Voting Systems is a current example of this technology.

The use of digital imaging technology to view the ballot does not necessarily imply more sophisticated mark recognition. For example, the Avante Vote-Trakker simply counts the number of dark and light pixels in each marking area to determine if the mark counts as a vote. More sophisticated mark recognition algorithms are sensitive to the shape of the mark as well as the total overall darkness, as illustrated by the ES&S Model 100, introduced in the mid 1990s.

...
Wikipedia