The Camera Behind the Screen: How Under-Display Sensors Chase a Bezel-Free Phone

01 Why the Front Camera Is the Last Bezel

The smartphone face has been collapsing for a decade. Side bezels shrank to slivers, the fingerprint reader migrated under the glass, and the earpiece hid behind a slit or the speaker itself. The one component that refused to disappear was the front camera, because unlike a speaker or a sensor, a camera needs unobstructed photons. The notch, the teardrop, and the punch-hole are all the same confession printed on the front panel: somewhere on this slab there must be a hole for light.

Mechanical workarounds tried to buy that real estate back. Motorized pop-up cameras appeared on several 2019 flagships, and slider designs hid the sensor inside the body, delivering a genuinely uninterrupted screen — at the cost of moving parts, ingress risk, and a failure mode no one missed when the trend faded. The industry learned the lesson quickly: a hole-free panel could not depend on a motor.

The under-display camera is the strategy that remains. Leave the panel completely intact and put the camera behind it. No hole, no motor, no compromise in industrial design — only physics, which turns out to be a much harder negotiation than any supplier.

02 How an Under-Display Camera Works

An under-display camera sits beneath a region of the display engineered to be porous to light. The pixels above the sensor are spread farther apart than elsewhere on the panel, deliberately reducing pixel density in a small patch. The wiring that would normally run densely between subpixels is rerouted through more transparent conductors, so a larger share of the area between pixels is optically open. Light falls through that lattice onto an otherwise conventional camera module.

The rest of the panel behaves normally. From typical viewing distance the eye fills in the sparse region and mostly perceives a continuous image, though a faint texture can be visible on light backgrounds at certain angles — the display equivalent of a watermark. Manufacturers accept that small blemish as the price of a hole-free front.

The teardown view makes the arrangement concrete. Peel the display assembly apart and the camera module appears behind the panel, staring up through a lattice of pixels and wiring, catching whatever light the gaps let fall. Nothing about the sensor itself is exotic; it is the screen above it that has been rebuilt to tolerate being looked through.

03 The Physics Problem: What the Screen Does to Incoming Light

A display is designed to emit light, and nearly everything that makes it good at emitting makes it bad at transmitting. The organic layers, the metal wiring, and the pixel structures all absorb part of the incoming light on its way down to the sensor. What does get through is shaped by the regular lattice of pixels, which diffracts it like a weak grating and smears fine detail. Color filters and uneven subpixel transmission shift the color balance on the way through.

The practical results are haze, softness, and low contrast: a camera that sees the world through a screen sees it dimmer, blurrier, and tinted. Because the sensor also receives light through only a small aperture fraction, less total signal arrives, which raises noise in anything less than bright conditions. Video calls in dim bedrooms are exactly the situation the hardware handles worst.

This is the central trade, stated plainly: every improvement in display quality over the camera region — denser pixels, fuller wiring coverage — makes the captured image worse, and every concession to the camera makes the display worse. There is no free parameter in the pile of materials between the lens and the outside world.

04 The Software Fix: Reconstructing What the Screen Removed

Since the hardware cannot pass clean light, manufacturers correct in software. Because the diffraction pattern of a fixed pixel lattice is predictable, the degradation is to a meaningful extent a known transformation: photograph a test chart through the panel, record what the lattice does to it, and learn the inverse of that operation.

In practice this means computational reconstruction — deconvolution to undo the diffraction blur, gain correction to compensate for the absorbed light, and white-balance correction to remove the color shift. Published vendor descriptions and teardown analyses suggest implementations trained on pairs of images captured with and without the screen in the optical path, letting a learned model restore much of the missing contrast.

The fix works within limits. Algorithms can restore plausibility to a face on a video call at social-platform compression, which is the dominant use case for a front camera. They cannot manufacture detail that never reached the sensor, and aggressive correction over-smooths skin into plastic. The gap between the marketing promise of a bezel-free flagship and the selfies it actually produces is where most of the disappointment lives.

05 The Commercial History: From the Axon 20 to the Fold Line

The ZTE Axon 20, released in 2020, is generally credited as the first mass-market phone with an under-display camera. It proved the concept could ship at retail, and it also itemized the bill: reviews of the era found selfies soft and the display region detectable. First is not the same as finished.

Samsung's turn came with the Galaxy Z Fold 3 in 2021, which introduced the company's Eco2 OLED display technology to hide the camera behind a foldable's expansive interior screen. The Fold line then iterated through 2022 and 2023, each generation refining the pixel arrangement over the sensor and the correction pipeline behind it. Competitors kept shipping under-display cameras in niche flagships, while most of the industry settled comfortably for the cheaper punch-hole.

The pattern is a familiar one in consumer hardware: a Chinese vendor ships the first engineering proof, a Korean giant industrializes a more polished version on a premium line, and the mass market waits — potentially for years — for the trade-offs to close.

06 The Trade-Off Triangle: Image Quality, Display Quality, Cost

Under-display camera design is a triangle with three vertices: image quality, display quality, and cost. Improving any one tends to tax the others. Spacing pixels farther apart improves the image and visibly degrades the display patch. Keeping pixel density high protects the display and starves the sensor. More sophisticated correction software costs compute, per-panel calibration, and tuning time on the production line.

The punch-hole wins because it sits at a corner of the triangle consumers already accept: near-perfect display quality, near-perfect image quality, and pennies of incremental cost. For the under-display camera to displace it, the entire triangle has to migrate toward that corner simultaneously — which is why progress arrives in increments rather than in leaps.

Foldables change the economics. A device that already commands a premium price can absorb the cost of an under-display camera on its inner screen, where a large panel makes a punch-hole especially distracting. That is why the Fold line, not a mid-range slab, has been the proving ground for the technology — the customer base is already paying for the privilege of fewer compromises.

07 Where the Technology Stands in 2026

Six years in, under-display cameras exist but have not taken over. Samsung's foldables continue to iterate, Chinese vendors continue shipping their versions, and the majority of mainstream phones still ship a punch-hole. The notch era ended; the punch-hole era has not.

The teardown evidence explains why. The screen in front of the sensor is not going away, and neither is the physics of what it does to incoming light. The advances are real — more transparent cathode materials, smarter pixel layouts, better learned reconstruction — but each gain is an increment against a fixed structural problem rather than a leap toward parity with an unobstructed lens.

The reasonable forecast is a slow merge rather than a victory. Under-display cameras become good enough for the way front cameras are actually used — video calls, and selfies destined for social-platform compression — and spread down from foldables as costs fall. Whether the front panel ever becomes truly nothing but pixels is less a question of if than of how long the physics keeps negotiating.