OCR-A font

OCR-A

Category	Sans-serif
Designer(s)	American Type Founders
Commissioned by	American National Standards Institute
Date released	1968[1]
Variations	OCR-A Extended

In the early days of computer optical character recognition, there was a need for a font that could be recognized by the computers of that day, and by humans.^[2] The resulting compromise was the OCR-A font, which used simple, thick strokes to form recognizable characters^[3]. The font is monospaced (fixed-width), with the printer required to place glyphs 0.254 cm (0.10 inch) apart, and the reader required to accept any spacing between 0.2286 cm (0.09 inch) and 0.4572 cm (0.18 inch).

Standardization

The OCR-A font was standardized by the American National Standards Institute (ANSI) as X3.4-1977. X3.4 has since become the INCITS and the OCR-A standard is now called ISO 1073-1:1976. There is also a German standard for OCR-A called DIN 66008.

Implementations

In 1968, American Type Founders produced OCR-A, one of the first optical character recognition typefaces to meet the criteria set by the U.S. Bureau of Standards. The design is simple so that it can be easily read by a machine, but it is more difficult for the human eye to read.^[4][5]

As metal type gave way to computer-based typesetting, Tor Lillqvist used MetaFont to describe the OCR-A font. That definition was subsequently improved by Richard B. Wales. Their work is available from CTAN.^[6]

To make the free version of the font more accessible to users of Microsoft Windows, John Sauter converted the MetaFont definitions to TrueType using potrace and FontForge in 2004.^[7] In 2007, Gürkan Sengün^[8] created a Debian package from this implementation.^[9]

In 2008. Luc Devroye corrected the vertical positioning in John Sauter's implementation, and fixed the name of lower case z.^[10]

Independently, Matthew Skala used mftrace^[11] to convert the Metafont definitions to TrueType format in 2006. In 2011 he released a new version created by rewriting the Metafont definitions to work with METATYPE1, generating outlines directly without an intermediate tracing step.^[12]

In addition to these free implementations of OCR-A, there are also implementations sold by several vendors.

Use

Although optical character recognition technology has advanced to the point where such simple fonts are no longer necessary, the OCR-A font has remained in use. Some lockbox companies still insist that the account number and amount owed on a bill return form be printed in OCR-A. In addition, some people prefer its unique style.

Code points

A font is a set of character shapes, or glyphs. For a computer to use a font then each glyph must be assigned a code point in a character set. When OCR-A was being standardized the usual character coding was the American Standard Code for Information Interchange or ASCII. Not all of the glyphs of OCR-A fit into ASCII, and for five of the characters there were alternate glyphs, which might have suggested the need for a second font. However, for convenience and efficiency all of the glyphs were expected to be accessible in a single font using ASCII coding, with the additional characters placed at coding points that would otherwise have been unused.

The modern descendant of ASCII is Unicode, also known as ISO 10646. Unicode contains ASCII and has special provisions for OCR characters, so some implementations of OCR-A have looked to Unicode for guidance on character code assignments.

Space, digits, and unaccented letters

OCR-A digits

OCR-A unaccented capital letters

OCR-A unaccented small letters

All TrueType implementations of OCR-A use U+0020 for space, U+0030 through U+0039 for the decimal digits, U+0041 through U+005A for the unaccented upper case letters, and U+0061 through U+007A for the unaccented lower case letters.

Regular characters

In addition to the digits and unaccented letters, many of the characters of OCR-A have obvious code points in ASCII. Of those that do not, most, including all of OCR-A's accented letters, have obvious code points in Unicode.

Additional OCR-A code points based on ASCII and Unicode

Name	Glyph	Unicode
Exclamation Mark		U+0021
Quotation Mark		U+0022
Number Sign		U+0023
Dollar Sign		U+0024
Percent Sign		U+0025
Ampersand		U+0026
Apostrophe		U+0027
Left Parenthesis		U+0028
Right Parenthesis		U+0029
Asterisk		U+002A
Plus Sign		U+002B
Comma		U+002C
Hyphen-Minus		U+002D
Full Stop (Period)		U+002E
Solidus (Slash)		U+002F
Colon		U+003A
Semicolon		U+003B
Less-Than Sign		U+003C
Equals Sign		U+003D
Greater-Than Sign		U+003E
Question Mark		U+003F
Commercial At		U+0040
Left Square Bracket		U+005B
Reverse Solidus (Backslash)		U+005C
Right Square Bracket		U+005D
Circumflex Accent		U+005E
Low Line		U+005F
Grave Accent		U+0060
Left Curly Bracket		U+007B
Vertical Line		U+007C
Right Curly Bracket		U+007D
Tilde		U+007E
Pound Sign (Sterling)		U+00A3
Yen Sign		U+00A5
Latin Capital Letter A with Dieresis		U+00C4
Latin Capital Letter A with Ring Above		U+00C5
Latin Capital Letter AE		U+00C6
Latin Capital Letter N with Tilde		U+00D1
Latin Capital Letter O with Stroke		U+00D8
Latin Small Letter O with Dieresis		U+00F6
Latin Small Letter U with Dieresis		U+00FC
OCR Hook		U+2440
OCR Chair		U+2441
OCR Fork		U+2442

Remaining Characters

John Sauter coded the remaining characters of OCR-A as follows:

Additional OCR-A Characters

Name	Glyph	Unicode	Unicode Name
Character Erase		U+007F	Delete
Long Vertical Mark		U+00A6	Broken Bar
Alternate Hyphen		U+00AD	Soft Hyphen
Alternate Apostrophe		U+00B4	Acute Accent
Alternate Period		U+00B7	Middle Dot
Alternate Comma		U+00B8	Cedilla
Alternate Question Mark		U+00BF	Inverted Question Mark

Exceptions

Some implementations do not use the above code point assignments for some characters.

PrecisionID

The PrecisionID implementation of OCR-A has the following non-standard code points:^[13]

• OCR Hook at U+007E
• OCR Chair at U+00C1
• OCR Fork at U+00C2
• Euro Sign at U+0080

Barcodesoft

The Barcodesoft implementation of OCR-A has the following non-standard code points:^[14]

• OCR Hook at U+0060
• OCR Chair at U+007E
• OCR Fork at U+005F
• OCR Belt Buckle at U+00DD

Moravia

The Moravia implementation of OCR-A has the following non-standard code points:^[15]

• OCR Hook at U+007E
• OCR Chair at U+00F0
• OCR Fork at U+005F
• Vertical Line at U+007C

IDAutomation

The IDAutomation implementation of OCR-A has the following non-standard code points:^[16]

• OCR Hook at U+007E
• OCR Chair at U+00C1
• OCR Fork at U+00C2
• OCR Belt Buckle at U+00C3

In addition, the IDAutomation implementation of OCR-A includes the Euro Sign character. The IDAutomation documentation does not specify the code point for the Euro Sign character. Since the code points for OCR Hook, OCR Chair and OCR Fork match those of PrecisionID, the IDAutomation OCR-A font may be a clone of the PrecisionID OCR-A font, in which case the Euro Sign would be coded as U+0080. The standard code point for Euro Sign is U+20AC.

OCR-A Extended

OCR-A Extended is an expanded version of the OCR-A font with 251 glyphs, 62 of which are composite glyphs, supporting the following languages in addition to English^{[citation needed]}:

• French
• German
• Italian
• Portuguese
• Dutch
• Spanish
• Icelandic
• Norwegian
• Danish
• Finnish
• Swedish
• Albanian

Sellers of font standards

• Hardcopy of ISO 1073-1:1976, distributed through ANSI, from Amazon.com
• ISO 1073-1 is also available from Techstreet, who distributes standards for ANSI and ISO

See also

• MICR
• Optical character recognition
• Westminster (typeface), another typeface designed to be machine-readable.
• OCR-B

Notes

1. ^ Background information about OCR-A from Linotype
2. ^ Motivation for OCR-A from Monotype and Linotype
3. ^ Background on OCR from Embedded Software Engineering
4. ^ Background on OCR-A from Adobe
5. ^ Some history of OCR fonts
6. ^ The MetaFont sources for OCR-A from CTAN
7. ^ John Sauter's 2004 OCR-A font from those MetaFont sources
8. ^ Gürkan Sengün's home page in Launchpad
9. ^ The ttf-ocr-a Debian package, based on John Sauter's SourceForge project
10. ^ Luc Devroye's font page, search for Sauter
11. ^ The mftrace Debian package
12. ^ Matthew Skala's 2011 OCR-A font from the MetaFont sources
13. ^ PrecisionID User Guide for the PrecisionID implementation of the OCR-A font
14. ^ Information page for the Barcode implementation of the OCR-A font
15. ^ Information page for the Moravia implementation of the OCR-A font
16. ^ Information page for the IDAutomation implementation of the OCR-A and OCR-B fonts

External links

• Information page of linotype.com OCR-A
• Introductory article about OCR fonts
• Link standard ANSI INCITS 17-1981 (R2002)
• Background on ISO work involving OCR-A
• Unicode code charts
• Debian package ttf-ocr-a
• Web-page where possible to download a free version of OCR-A