As smartphone-based authentication becomes a mainstream strategy in anti-counterfeiting, printed security features are frequently positioned as cost-effective, scalable solutions. Techniques such as copy-detection patterns rely on the longstanding principle that copies of detailed prints become blurry and lose detail. However, a critical technical limitation undermines their reliability: Any printed security feature that uses smartphone authentication can be reproduced using widely available home digital printers.

This article provides a science backed analysis to explain in layman terms why printed security features are inherently insecure when paired with smartphone authentication.

Smartphone cameras have made major advances in pixel count over the past decade. However, the actual level of detail they can capture isn’t determined just by how many megapixels they have — it’s limited by basic optical physics, especially diffraction and the size of the lens opening (aperture).

As shown in our recent whitepaper, even high-end smartphones today — with sensors up to 108 megapixels — are physically limited to capture details only down to 20–50 micrometers in size. Mid-range Smartphone Cameras only 40-60 micrometers.

Why this happens:
Smartphone camera lenses have very small physical diameters causing every point of light to spread by diffraction into an airy-disk blur on the sensor. This unavoidable blur limits how much fine detail the camera can resolve—no matter how many megapixels the sensor has.

In practical terms, this means smartphone cameras cannot detect printed features smaller than 20–50 micrometers unless extra equipment like clip on lenses are used. For typical hand-held product authentication using a smartphone, this is a serious limitation.

In contrast to the optical limits of smartphone cameras, digital printing systems are capable of producing micro-features far smaller than a smartphone can resolve.

Even standard desktop printers under €500 can achieve resolutions of 1200–2400 DPI, printing dots as small as 10–20 micrometers—well below the resolution threshold of a smartphone camera.

Figure 2. Printer resolution vs Smartphone Camera

On the left, you see both the original security feature and a copy done by a low-cost desktop printer. The copied security feature looks a bit more blurry and less detailed. On the right, you see how these features appear to be similar when captured by a smartphone camera.

Smartphones increasingly use computational photography techniques such as multi-frame super-resolution and AI-assisted sharpening. While these methods can enhance perceived image quality, they do not overcome the physical diffraction limit.

AI can optimize the available optical information by increasing sampling density and averaging out noise, but it cannot recreate information that has been lost due to the diffraction blur.

This means that no amount of AI or software processing can recognize features smaller than what the optical lens physically delivers to the sensor.

In the current technological landscape, digital printers have outpaced the resolving power of smartphones. Consequently, any printed security feature that a smartphone can read is vulnerable to reproduction by accessible printing technology.

Printed security features, such as copy-detection patterns, are suitable for low-budget scenarios with minimal protection requirements. However, in environments with known counterfeiting risks, these printed features no longer provide sufficient security. Today, sustainable protection via mobile authentication primarily relies on two robust solutions: NFC chips for low-volume, high-value products, and scalable, physically unclonable multi-dimensional features—such as holographic fingerprints—that remain secure under scrutiny and convenient for everyday use.

Authentic Vision welcomes dialogue with brands and solution architects seeking to elevate their security posture beyond what standard printing can support.