UV vs MG vs IR vs CIS: Counterfeit Detection Technologies Explained

Modern banknotes incorporate an array of sophisticated security features designed to make counterfeiting as difficult as possible. Watermarks, security threads, color-shifting ink, microprinting, and holographic elements all serve as layers of defense. But relying on the human eye alone to verify these features is slow, inconsistent, and increasingly inadequate as counterfeit quality improves.

Automated counterfeit detection in bill counters and currency sorters uses four main technologies: UV (ultraviolet), MG (magnetic), IR (infrared), and CIS (contact image sensor). Each catches different types of counterfeit attempts, and the best protection comes from combining them. This guide explains what each technology does, how it works, and what happens when a counterfeit note encounters it.

UV Detection: The First Line of Defense

How It Works

UV detection relies on the fluorescent properties of genuine banknote paper. Central banks incorporate fluorescent fibers or threads into the paper substrate during manufacturing. These fibers glow in specific colors under ultraviolet light (typically 365 nm wavelength). Additionally, certain design elements on genuine notes are printed with fluorescent inks that only become visible under UV illumination.

In a bill counter, UV LEDs illuminate each note as it passes through the transport path. Photodiodes or phototransistors on the opposite side measure the fluorescent response across multiple spectral bands. The machine compares the measured response against expected values for the genuine note.

What UV Catches

• Basic paper counterfeits: Standard office paper contains optical brighteners that glow brightly under UV, while genuine banknote paper typically has little or no brightener response. A note made from common paper will fluoresce intensely and be rejected immediately.
• Inkjet/laser counterfeits: Consumer-grade printed notes often lack fluorescent features entirely, or the counterfeit printer uses inks that fluoresce differently than genuine currency inks.
• Bleached notes: Criminals sometimes bleach genuine low-value notes and reprint them as higher denominations. UV detection can catch these when the bleaching process damages the original fluorescent fibers.

What UV Misses

• Professional offset counterfeits: Well-equipped counterfeit operations use paper that closely mimics the fluorescent properties of genuine currency.
• Partial counterfeits (genuine paper, overprinted): A genuine note that has been skillfully altered may retain its correct UV fluorescence while still being fraudulent.
• Currency with minimal fluorescence: Some banknote series use very low levels of fluorescent material, making UV detection less discriminating.

MG (Magnetic) Detection: Reading the Ink

How It Works

Genuine banknotes use magnetic ink containing iron oxide particles in specific regions of the note. The portrait area, denomination numerals, and certain design elements are typically printed with magnetic ink. Each note has a unique magnetic signature pattern based on which elements use magnetic ink and the magnetic field strength of those elements.

Magnetic sensors in a bill counter are typically placed above and below the transport path. As a note passes, the sensors detect the presence, intensity, and distribution pattern of magnetic material. The machine compares this pattern against the stored profile for the genuine note.

What MG Catches

• Notes without magnetic ink: Most basic counterfeits are printed with standard (non-magnetic) inks and will show zero magnetic response.
• Wrong magnetic pattern: A counterfeit that uses some magnetic ink but in the wrong locations or wrong intensity will fail pattern matching.
• Altered notes: When numbers or other magnetic elements are physically altered, the magnetic pattern changes in detectable ways.

What MG Misses

• Sophisticated magnetic reproductions: Some professional counterfeiters source magnetic inks with properties very close to genuine currency inks and apply them in the correct patterns.
• Magnetic material degradation: Well-circulated genuine notes can lose magnetic properties over time due to wear and folding, causing false positives (genuine notes flagged as suspect).

IR (Infrared) Detection: Seeing Through the Surface

How It Works

Infrared detection exploits a fundamental property of banknote security: certain inks used on genuine currency are transparent to infrared light at specific wavelengths, while other inks absorb IR. This creates a pattern that is invisible to the naked eye but distinct under IR illumination.

When an IR sensor shines infrared light (typically 850–940 nm) onto a passing note, some regions of the note absorb the IR light (appearing dark to the sensor) while other regions allow it to pass through or reflect it (appearing light). The pattern of dark and light regions is unique to each denomination and series.

This property is extremely difficult for counterfeiters to reproduce because they would need to source inks with the exact same IR transmission characteristics as the central bank's proprietary ink formulations.

What IR Catches

• Most commercial counterfeits: Standard printing inks (toner, inkjet, offset) have very different IR properties than genuine currency inks. A note printed with ordinary inks will produce an IR pattern that looks nothing like the genuine note.
• High-quality counterfeits that pass UV and MG: IR provides a third independent layer of verification that catches notes that fooled the first two.

What IR Misses

• Very sophisticated counterfeits using custom inks: Extremely rare but possible at the most professional level.
• Notes with physical damage: Patches, tape, or heavy soiling can alter IR absorption patterns and cause false positives.

CIS (Contact Image Sensor): The Gold Standard

How It Works

A Contact Image Sensor is fundamentally different from UV, MG, and IR sensors. Instead of measuring one or two specific physical properties, CIS captures a complete image of the note and performs full visual verification. The CIS module consists of a linear array of light-sensitive cells (typically 200–300 DPI resolution) combined with RGB and IR LED light sources.

As the note passes over the sensor, the CIS module sequentially illuminates it with red, green, blue, and infrared light, capturing separate images at each wavelength. This produces a multi-spectral image set of each note. The machine then analyzes this image set to verify dozens of security features simultaneously:

• Overall dimensions (length and width, which vary by denomination)
• Watermark position and shape
• Security thread position, width, and magnetic properties
• Portrait alignment and feature positions
• Microprinting legibility
• Color accuracy across multiple regions of the note
• IR transmission patterns at high resolution

CIS-based detection is the technology used in mixed denomination counters, where the machine must not only verify authenticity but also determine the note's value.

What CIS Catches

• All of the above: Because CIS combines image analysis with spectral analysis, it catches everything UV, MG, and IR catch individually, plus many more subtle indicators.
• Partial counterfeits: A genuine note with a fraudulent overprint, a note assembled from two genuine halves of different values, or a note with a altered denomination numeral.
• Series mismatches: If a note claims to be a 2017 series but its security features match the 2004 series profile, CIS catches the discrepancy.
• Worn genuine notes that look counterfeit: Counterintuitively, CIS can reduce false positives compared to individual UV/MG/IR tests because it uses the full image context rather than isolated feature measurements.

Why Multi-Layer Detection Matters

No single detection technology is foolproof. Each has known weaknesses that sophisticated counterfeiters can exploit. The principle of multi-layer detection is that a counterfeit must fail all tests simultaneously to pass verification, which is exponentially more difficult than defeating any single test.

For low-value transactions in low-risk environments, UV-only detection may be adequate. For banks, casinos, and high-value retail, minimum UV+MG+IR is recommended. For cash processing centers, central banks, and any operation handling large volumes of mixed currency, CIS-based detection is the appropriate standard.

Detection Levels in FEELTECK Products

FEELTECK bill counters are available at every detection level:

• UV-only: Entry-level models like the FT-501 for basic counting tasks
• UV+MG: Mid-range models for retail and small business use
• UV+MG+IR: Professional-grade counters like the FT-2040 for banks
• CIS (full multi-spectral): The FT-8288, FT-7100, FT-900, and FT-910 for complete verification and mixed denomination sorting

For portable on-the-spot verification, the FT-D300 and FT-V30 cash detectors combine UV, MG, and IR detection in a compact handheld form factor ideal for retail counters and teller stations.

Frequently Asked Questions

Can a counterfeit pass all four detection methods?

Theoretically, yes — an exceedingly well-produced counterfeit that uses the correct paper, magnetic inks with the right pattern, IR-matching inks, and visually identical printing could pass all four. Such notes are extremely rare and are typically the work of state-sponsored or highly organized criminal operations. Multi-layer detection raises the bar high enough that 99.9%+ of counterfeit attempts are caught.

Do counterfeit detection sensors need calibration?

Yes. UV lamps dim over time. MG sensors accumulate dust. IR LED output degrades. Most professional machines include self-diagnostic routines. FEELTECK recommends a full sensor calibration check every 6 months for high-volume operations.

How often are counterfeit detection databases updated?

Whenever a new banknote series is released. FEELTECK provides free database updates for 24 months from purchase. After that, annual update subscriptions are available.

Which detection method is most important for retail?

For most retail environments, UV+MG provides adequate protection. The most important factor is actually consistent use — a machine that is bypassed because it is slow or inconvenient provides zero protection. Choose a machine fast enough that staff will use it on every transaction.