Optical Mark Recognition (OMR): Working Principle and Pros and Cons

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Optical Mark Recognition (OMR): Working Principle and Pros and Cons

Optical Mark Recognition, as a technology, has been used in our daily lives whether we are aware of it or not. To learn more about the working of OMR, and its pros and cons, go through this Techspirited article.

The Nigerian Army used optical mark recognition to recruit its candidates based on merit.

Optical Mark Recognition is a technology that uses a special device called Optical Mark Reader to detect the presence or absence of marks on a specially printed paper called OMR form. This technology is usually used if bulks of data, especially answers to MCQ (Multiple Choice Questions), are to be gathered and processed in a short period of time. For instance, when the answer sheets of competitive exams held on a larger scale, need to be a evaluated within a few days’ time, OMR technology comes to help. In this Techspirited article, we will discuss what this technology is all about, along with its applications, and its pros and cons.

What is an Optical Mark Recognition?
It is the process of reading data from specialized forms and storing it into the computer system. The data to be interpreted is in the form of markings such as dashes, dots, ticks, darkened circles, etc. An OMR form is passed through an OMR reader, which identifies the marked areas, extracts the information, and stores it in separate files.

What is an Optical Mark Reader and How Does it Work?
Optical Mark Reader (OMR scanner) is a special scanning device used for the purpose of reading pencil marks made on pre-defined positions on the OMR form.

The working principle of optical mark recognition is based on the ‘Law of Reflection’, which states that ‘all reflected light obeys the relationship that the angle of incidence equals the angle of reflection’. This means that a lighter surface reflects more light than a darker one. Accordingly, the OMR scanner uses its sensors to detect the dark pencil-marked areas on the OMR form because they are less reflective than the unmarked areas. There are around 48 sensors which do this job. If the scanner senses a half-filled form, it’ll return an error or mark it as false (or wrong), else the information is converted into a computer data file.

What is an OMR Form?
An OMR form is a specialized form created specifically for the OMR system by special form-design software. The form comprises multiple-choice questions which are placed such that the circles provided for answers and the sensors on the scanner are in exact alignment. The number of columns on the form is equal to the number of sensors, i.e., 48, whereas the number of rows may vary from 53 to 80. One important feature of an OMR form is that it has timing tracks on one side of the form. A timing track is a rectangular block which acts as a pointer to a row on the form. The purpose of this block is to inform the scanner where to read for pencil marks.

Pros and Cons of Optical Mark Recognition

OMR is accurate in collecting data and interpreting on a simple Yes/No answer.

It eliminates the need for manual entry of data, and thereby minimizes the risk of human error.

It decreases the investment cost since only a single computer is needed to store the data.

OMR forms are easy to read since they are marked with a pencil. The simplicity aids in saving time and effort.

If a mark is too light, the optical mark reader would be unable to read it.

The OMR reader needs the answers on the forms to be identical to each other.

The answer sheet can’t be torn or folded in any way. It should be clean or devoid of any dirt or marks. If the answer is incomplete, the scanner won’t be able to read it.

Optical Mark Recognition (OMR) is used in applications consisting of large amounts of data. It is used extensively to process competitive exam results, or responses to feedback forms, survey forms, and questionnaires. It is also used at the state level to determine the election results. The areas where OMR is used are discussed below:

Consumer surveys
Consumer surveys are often conducted for market research by various companies. Since large volumes of data need to be collected and processed in this regard, the OMR technology is used.

Census Data Processing
OMR is used to scan geocodes to match any of the geocodes available in the master census geocode file. A geocode is a geographical co-ordinate that maps to a physical address, for instance, a postal code.

Test Sheets
Examination sheets used for competitive exams like SAT and GMAT are scanned using OMR technology. The results are calculated based on the markings on the sheet and compiled into a database.

Election Poll Results
OMR is also used to count votes in general elections. This helps curtail cheating methods of rigging the election and vote counting.

Inventory Count
Recent developments have introduced the concept of two-dimensional codes called bar codes. Warehouses and supermarkets use OMR technology to keep track of the products using these bar codes.

It’s used to mark numbers for reading the lucky lottery numbers.

These are some of the ways in which optical mark recognition makes our life easier. OMR technology was prevalent in the form of punch cards, but has retained its existence in the form of scanners. This just goes to prove that technology doesn’t fizzle out but evolves with us.

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