Saturday, March 9, 2013

Document Readers

Document Readers

A document reader is a device which can read data straight from forms. Examples of documents read by document readers

1 A card on which pencil marks are made by hand.

2 A multiple choice question paper with pencil marks to show the candidate's choices.

3 A bank cheque with numbers along the bottom in magnetic ink .

4 A slip filled in by a gas board meter reader (see Fig 3). The customer's address and account number are printed by a line printer. The meter reading has been filled in pencil.

Types of data read by document readers

1 Marks

Short lines made by hand-they are usually in pencil on cards or documents.

2 Handwritten characters

When documents are to be filled in by hand they are preprinted with spaces provided. The characters have to be written carefully in the right places.

3 Printed lines

The most common of these is the bar code.

4 Printed characters

Examples are:

(a) Numbers which have been output on to documents by a line printer. (b) Magnetic ink characters on bank cheques.

MARK READING

Document Readers

Methods of reading marks

1 Mark sensing

Small electrical 'brushes' touch the surface of the document or card. When they contact a penciJ mark a circuit is completed. The marks must be in a soft pencil as this contains graphite, which conducts electricity.

2 Optical mark reading (OMR)

A beam of light is directed on to the surface of the card or document. The beam is reflected from the surface to a light sensor. When a mark passes under the beam less light is reflected back and the presence of the mark is registered.

Advantages

Of OMR compared with mark sensing

The sensitivity of optical readers can be altered to allow for different surfaces and different pencils or inks.

Of marks compared with handwritten characters

There are fewer recognition failures.

Of marks and characters compared with keyboard preparation

1 Data can be prepared at the place where it originates.

2 No machines are required for the preparation.

Disadvantages

Of marks compared with characters

Documents for mark readers are more complicated. If an item has several values then a mark space has to be allocated for each value.

Of marks compared with data prepared using a keyboard

1 Input of data to the computer is slow. For example a marked card reader is far slower than a disc unit.

2 It is difficult to verify marked data.

3 Documents for a mark reader are difficult to understand and to fill in.

4 A document reader has to be reprogrammed for each new design of document.

Uses of mark reading

In situations where:

1 The data to be input is simple.

2 The volume of data is large enough to justify designing special documents for it.

Examples of uses

1 For multiple choice examination papers.

2 For data collected 'in the field' by research workers.

3 For market research questionnaires.

4 In supermarkets for reordering stock.

CHARACTER RECOGNITION

Description

The document reader recognizes characters which have been printed by machine or by hand. The shape of each character is analysed by the document reader and compared with a set of known shapes, and either the character is recognized or the document is rejected to be dealt with in another way.

Methods of inputting characters

1 Optical character recognition (OCR)

The character shapes are recognized by sensing light reflected from the paper and from the ink (as with OMR) but the reader has to have a memory and a processing capability in order to work out what the characters are.

A font is a character set of a particular size and style. Practically all OCR document readers recognize at least one of two fonts known as OCRA and OCRB. Many also recognize other typed or printed fonts. Some cope with hand-printed characters (sometimes only numbers) provided that they are done carefully to copy a standard font.

2 Magnetic ink character recognition (MICR)

Characters are printed using an ink containing iron oxide. As the document passes into the reader the ink is magnetized, so that the character shapes can then be recognized electrically.

Readers usually read a font known as font E13B (at least in this country) (Figs 5 and 6).

This contains only 14 characters- the digits 0 to 9 and four special symbols.

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Fig 5 A bank cheque showing characters in font EI3B (By kind permission of Lloyds Bank)

Fig 6 the font E13B character set

Advantages

Of MICR over OCR

1 it is difficult to forge.

2 Documents can still be read when folded, written on, etc.

Of OCR over MICR

More different fonts can be used, including sometimes handprinting and normal type.

Of characters compared with marks Design of forms is less complicated.

Of characters over other media

Data can be read by other people.

Disadvantages

Of MICR compared with other media

1 Readers are very expensive.

2 Only certain fonts are acceptable.

Of hand-printed characters

There is a high rejection rate (perhaps 5 per cent).

Of printed characters

A high standard of printing is needed.

Uses

Of MICR

Where printed numbers in a standard format are to he read in large volume. For example the major British hanks all use MICR to encode along the bottom of cheques the following information: (a) cheque number (h) branch number of the bank (c) the customer's account number (d) (after the cheque has been banked) the amount of money.

Of OCR

1 Situations where data has been typed or printed for people to read. If OCR is used the data does not need to be retyped for entry to a computer.

2 It is particularly useful for turnaround documents , where some characters are printed by a computer printer and others are added later by hand.

For example, in the case of a charity fund, where names and addresses of prospective donors are preprinted on donation forms, each donor sends back a form with some money. The date and amount given are carefully hand printed on the form by an operator.