What Are the Disadvantages of MICR?

MICR characters are used at the bottom of bank checks.

Magnetic ink character recognition (MICR, pronounced my-kur or micker) is a technology which allows numerical characters to be read by high-speed scanners through the use of iron oxide ink. It is most commonly used on bank checks in the United States, Great Britain and many European countries.

The Facts

MICR characters are written with a specially formulated laser printer toner cartridge, which has been infused with iron oxide particles. Iron oxide (which in large quantities is usually known as rust) is the same substance used to store information on computer hard drives. When the document is run through a scanner equipped for MICR, the MICR characters are magnetically charged and read off of the page.

History

MICR was formalized by the International Organization for Standardization (known by its French initials, ISO) in 1983 in its publication ISO 2033: "Information processing--Coding of machine readable characters (MICR and OCR)."

Character Set Limitations

MICR characters are limited to the ten numbers 0 through 9, and four special characters which do not correspond to alphanumeric characters; these are used to mark the beginning and end of database fields, such as account numbers and bank routing information.

Considerations

The primary limitations of MICR are use of a single font, restrictions to only numeric information within that font and the operating cost of MICR printers and scanners. As of November 2009, a single toner cartridge for a MICR printer cost $580, far higher than the cost of equivalent plain ink toner cartridges. Compare this with standard optical character recognition (OCR), which digitizes characters off a printed page by recognizing the contrast between the ink and paper; OCR can recognize a wide variety of fonts and the full character set of each font, and does not require special magnetic ink. However, OCR has a higher error rate than MICR, so MICR is used in financial applications where the error rate must be minimized, even at high cost.

Misconceptions

Many third-party developers have released MICR-style fonts for use on home and business computers; these mimic the appearance of true ISO 2033 characters, and extend the font to include a full alphabetic range of characters. However, these should not be considered true MICR, which is solely defined by the ISO 2033 specification. Of course, even if the font matches MICR, if it is not printed in magnetic ink, it will not be readable by an MICR scanner.

References

• Input devices: identification and use
• Information processing -- Coding of machine readable characters
• Source Technologies ST9530 printer

Resources

• MICR fonts