Optical mark recognition (OMR) collects data from people by identifying markings on a paper.

OMR enables the hourly processing of hundreds or even thousands of documents. A common application of this technology is used in exams, where students mark cells as their answers. This allows for very fast automated grading of exam sheets.

Background

thumb|OMR tests form, with registration marks and drop-out colors, designed to be scanned by dedicated OMR device

Many OMR devices have a scanner that shines a light onto a form. The device then looks at the contrasting reflectivity of the light at certain positions on the form. It will detect the black marks because they reflect less light than the blank areas on the form.

Some OMR devices use forms that are printed on transoptic paper. The device can then measure the amount of light that passes through the paper. It will pick up any black marks on either side of the paper because they reduce the amount of light passing through.

In contrast to the dedicated OMR device, desktop OMR software allows a user to create their own forms in a word processor or computer and print them on a laser printer. The OMR software then works with a common desktop image scanner with a document feeder to process the forms once filled out.

OMR is generally distinguished from optical character recognition (OCR) by the fact that a complicated pattern recognition engine is not required. That is, the marks are constructed in such a way that there is little chance that the OMR device will not read them correctly. This does require the image to have high contrast and an easily recognizable or irrelevant shape. A related field to OMR and OCR is the recognition of barcodes, such as the UPC bar code found on product packaging.

One of the most familiar applications of OMR is the use of #2 pencil (HB in Europe) bubble optical answer sheets in multiple choice question examinations. Students mark their answers, or other personal information, by darkening circles on a forms. The sheet is then graded by a scanning machine.

  • In the United States and most European countries, a horizontal or vertical "tick" in a rectangular "lozenge" is the most commonly used type of OMR form;
  • The most familiar form in the United Kingdom is the UK National lottery form.

Lozenge marks represent a later technology that is easier to mark and easier to erase. The large "bubble" marks are legacy technology from very early OMR machines that were so insensitive a large mark was required for reliability. In most Asian countries, a special marker is used to fill in an optical answer sheet. Students, likewise, mark answers or other information by darkening circles marked on a pre-printed sheet. Then the sheet is automatically graded by a scanning machine.

Many of today's OMR applications involve people filling in specialized forms. These forms are optimized for computer scanning, with careful registration in the printing, and careful design so that ambiguity is reduced to the minimum possible. Due to its extremely low error rate, low cost and ease-of-use, OMR is a popular method of tallying votes.

OMR marks are also added to items of printed mail so folder inserter equipment can be used. The marks are added to each (normally facing/odd) page of a mail document and consist of a sequence of black dashes that folder inserter equipment scans in order to determine when the mail should be folded then inserted in an envelope.

Optical answer sheet

thumb|350x350px|A response to an [[SAT math question marked on an optical answer sheet]]

An optical answer sheet or bubble sheet is a special type of form used in multiple choice question examinations. OMR is used to detect answers. The Scantron Corporation creates many optical answer sheets, although certain uses require their own customized system.

Optical answer sheets usually have a set of blank ovals or boxes that correspond to each question, often on separate sheets of paper. Bar codes may mark the sheet for automatic processing, and each series of ovals filled will return a certain value when read. In this way students' answers can be digitally recorded, or identity given.

Reading

The first optical answer sheets were read by shining a light through the sheet and measuring how much of the light was blocked using phototubes on the opposite side. As some phototubes are mostly sensitive to the blue end of the visible spectrum, blue pens could not be used, as blue inks reflect and transmit blue light. Because of this, number two pencils had to be used to fill in the bubbles—graphite is a very opaque substance which absorbs or reflects most of the light which hits it. In contrast, OMR software users design their own mark-sense forms with a word processor or built-in form editor, print them locally on a printer, and can save thousands of dollars on large numbers of forms.

Identifying optical marks within a form, such as for processing census forms, has been offered by many forms-processing (Batch Transaction Capture) companies since the late 1980s. Mostly this is based on a bitonal image and pixel count with minimum and maximum pixel counts to eliminate extraneous marks, such as those erased with a dirty eraser that when converted into a black-and-white image (bitonal) can look like a legitimate mark. So this method can cause problems when a user changes their mind, and so some products started to use grayscale to better identify the intent of the marker—internally scantron and NCS scanners used grayscale.

OMR software is also used for adding OMR marks to mail documents so they can be scanned by folder inserter equipment. An example of OMR software is Mail Markup from UK developer Funasset Limited. This software allows the user to configure and select an OMR sequence then apply the OMR marks to mail documents prior to printing.

History

Optical mark recognition (OMR) is the scanning of paper to detect the presence or absence of a mark in a predetermined position. With modern OMR, where the presence of a pencil filled in bubble is recognized, the recognition is done via an optical scanner.

The first mark sense scanner was the IBM 805 Test Scoring Machine; this read marks by sensing the electrical conductivity of graphite pencil lead using pairs of wire brushes that scanned the page. In the 1930s, Richard Warren at IBM experimented with optical mark sense systems for test scoring, as documented in US Patents 2,150,256 (filed in 1932, granted in 1939) and 2,010,653 (filed in 1933, granted in 1935). The first successful optical mark-sense scanner was developed by Everett Franklin Lindquist as documented in US Patent 3,050,248 (filed in 1955, granted in 1962). Lindquist had developed numerous standardized educational tests, and needed a better test scoring machine than the then-standard IBM 805. The rights to Lindquist's patents were held by the Measurement Research Center until 1968, when the University of Iowa sold the operation to Westinghouse Corporation.

During the same period, IBM also developed a successful optical mark-sense test-scoring machine, as documented in US Patent 2,944,734 (filed in 1957, granted in 1960). IBM commercialized this as the IBM 1230 Optical mark scoring reader in 1962. This and a variety of related machines allowed IBM to migrate a wide variety of applications developed for its mark sense machines to the new optical technology. These applications included a variety of inventory management and trouble reporting forms, most of which had the dimensions of a standard punched card.

While the other players in the educational testing arena focused on selling scanning services, Scantron Corporation, founded in 1972, had a different model; it would distribute inexpensive scanners to schools and make profits from selling the test forms. As a result, many people came to think of all mark-sense forms (whether optically sensed or not) as scantron forms.

In 1983, Westinghouse Learning Corporation was acquired by National Computer Systems (NCS). In 2000, NCS was acquired by Pearson Education, where the OMR technology formed the core of Pearson's Data Management group. In February 2008, M&F Worldwide purchased the Data Management group from Pearson; the group is now part of the Scantron brand.

OMR has been used in many situations as mentioned below. The use of OMR in inventory systems was a transition between punch cards and bar codes and is not used as much for this purpose.

Applications

thumb|OMR betting form used in [[Japan Racing Association Fukushima Racecourse, Japan.]]

thumb|Betting ticket using this form.

There are many other applications for OMR, for examples:

  • In the process of institutional research
  • Community surveys
  • Consumer surveys
  • Tests and assessments
  • Evaluations and feedback
  • Data compilation
  • Product evaluation
  • Time sheets and inventory counts
  • Membership subscription forms
  • Lotteries and voting
  • Geocoding (e.g. postal codes)
  • Mortgage loan, banking, and insurance applications

Field types

OMR has different fields to provide the format the questioner desires. These fields include:

  • Multiple, where there are several options but only one is chosen. For example, the form might ask for one of the options ABCDE; 12345; completely disagree, disagree, indifferent, agree, completely agree; or similar.
  • Grid: the bubbles or lines are set up in a grid format for the user to fill in a phone number, name, ID number and so on.
  • Add, total the answers to a single value
  • Boolean, answering yes or no to all that apply
  • Binary, answering yes or no to only one
  • Dotted lines fields, developed by Smartshoot OMR, allow border dropping like traditional color dropping.

Capabilities/requirements

In the past and presently, some OMR systems require special paper, special ink and a special input reader (Bergeron, 1998). This restricts the types of questions that can be asked and does not allow for much variability when the form is being input. Progress in OMR now allows users to create and print their own forms and use a scanner (preferably with a document feeder) to read the information. The user is able to arrange questions in a format that suits their needs while still being able to easily input the data. OMR systems approach one hundred percent accuracy and only take 5 milliseconds on average to recognize marks. There is also the possibility of missing data in the scanning process, and incorrectly or unnumbered pages can lead to their being scanned in the wrong order. Also, unless safeguards are in place, a page could be rescanned, providing duplicate data and skewing the data.