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Acceptance rate
The acceptance rate -
- Of the OCR machine is defined as the percentage of addresses on letters the OCR was able to successfully recognise out of a given number of letters;
- is influenced by a number of parameters, one of which is the type of font used;
- depends largely on the fonts used on letters to be processed by the OCR.
Reason
The computer controlling the reader electronics of the OCR has to decide where to sort a letter within a limited time.
Result
When the computer cannot reach a decision after applying all character recognition methods within a certain time, the letter is sent to the reject stacker of the machine and has to be hand sorted. Hand sorting may delay the delivery of the letter for up to one day and is more costly.
Why is the computer unable to reach a decision in a certain time?
The computer is programmed to recognise pure ASCII characters as the basis of all printed fonts When confronted with certain variations of type of font, it may not reach a decision within a specific time.
All other font characters have to be compared with these ASCII characters. The comparison process obviously takes time and the possibility exists that the time available for comparing may run out. The letter will then be rejected.
Most acceptable fonts
The most acceptable fonts in order of the highest acceptance rate are:
- Standard ASCII characters (uniform character spacing)
- All non-proportionally spaced fonta such as Courier-type fonts
- Simple serif fonts such as Times New Roman (on a word processor use the expanded option) - see section on font sizes)
- Simple sans-serif fonts such as Arial
Any font that allows characters to touch each other or to be too close to each other is not acceptable.
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