The use of omr is not limited only to the grading of

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Unformatted text preview: ake advantage of the fact that when we read a handwritten document, we have a good idea of its context (what the topic is). Hence we can often read a handwritten document even if we can decipher only a few letters in each word. But teaching a computer to perform the same task is really difficult. Optical Mark Reader (OMR) These scanners are capable of recognizing a pre-specified type of mark made by pencil or pen. For example, many students might have appeared in objective type tests where they had to mark their answers to questions on a special pre-printed test scoring sheet by darkening a small square, circular or oval shaped box by a pencil to indicate their correct choice out of the various given options (see Figure 9.12). These answer sheets are directly fed to a computer for grading with the use of an optical mark reader. The actual technique used by an OMR device for recognition of marks involves focusing a light on the page being scanned and detecting the reflected light pattern from the marks. Pencil marks made with a soft lead pencil (high graphite content) reflect the light enabling the reader to determine which responses are marked. Note that OMR devices require that the pre-printed forms use good quality paper and the boxes to be marked on them are accurately aligned for correct interpretation of input data. Furthermore, the pre-printed forms should not be folded so that the marks can be read correctly. The use of OMR is not limited only to the grading of objective type tests. In fact, any input data that is of a choice or selection nature can be recorded for OMR input. Thus OMR is very useful for grading tests with objective type questions in which a large number of students appear and for researchers who need to tabulate responses to large surveys where responses can be restricted to one or more out of a few possibilities. Bar-Code Reader Data coded in the form of small lines (known as bars) are known as bar codes. Bar codes represent alphanumeric data by a combination of adjacent vertical lines (bars) by varying their width and the spacing between them. They are particula...
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This document was uploaded on 04/07/2014.

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