Magnetic ink consists of standard ink plus additional iron oxide particles. These particles can be magnetized by an outer magnetic field to be analysed and read out. Therefore magnetic ink combines the visibility of ordinary ink with electronic processing and readout cabability as well as fraud protection of magnetic particles. Mostly used in the U.S. for cheque-transfer protection and processing the MICR - Magnetic Ink Character Recognition - is read out by using Hall probes in order to detect the unique waveform pattern of MICRs fontset standardized by ISO 1004:1995.

By using magneto-optical systems as the cmos-magview the huge advantage of MICR code - well printed MICR documents‘ "can't read"-rate is usually less than 1% while the substitution rate (misread rate) is in the order of 1 per 100,000 characters which is by far a smaller error rate as when using optical recognition systems - can be extended due to magneto-optical systems can be applied everywhere in real time.

Due to magneto-optical method‘s results are optical inspectable and processable, a time consuming computerized analysis of the magnetic field intensities (in order to assign each character‘s unique definied intensity pattern with the measured intensity pattern of the single cheque) is not neccesary. Magneto-optical visualizations of MICR-compatible fonts can be evaluated and processed by comparison to the standard ink characters.