When the Screen Starts Looking Back

The Digital Retina

A digital camera works by allowing light to hit a sensor made up of millions of tiny light-sensitive points. Each point records a small part of the light reaching the sensor, and together these points build an image. A screen works, in a sense, in the opposite direction. It takes digital information and converts it into light that is sent towards our eyes. One technology receives light, the other produces it. That is why the idea is not as strange as it first appears: why should the same surface not be able to do both? A future display could consist of pixels or sensor elements capable of both emitting light and detecting incoming light. It could function as both a display and an optical sensor. This is the idea behind what we might call a digital retina — a surface that no longer simply displays information but also perceives its surroundings.

When the Lens Disappears

Perhaps the most important change is not that the screen can see, but that the camera as a physical symbol disappears. Today, we can still detect many cameras. We can place a piece of tape over the webcam on a laptop or close a physical shutter. At least we know where the sensor is located. But if the entire screen becomes the sensor, there is no small lens to cover. A two-metre-wide advertising display could potentially be as much a camera as an information surface. You could stand in front of it without knowing whether it is simply showing an advertisement or simultaneously analysing how long you look at it, where you are standing, how you move and which part of the image captures your attention. Surveillance then becomes harder to identify because it no longer needs to look like surveillance.

The Advertising Screen That Observes

Imagine walking through a shopping centre and passing a large digital advertising screen. You see a car in the advertisement and stop for a few seconds. Your gaze moves first to the vehicle and then to the price. Then you continue walking. To you, the moment is insignificant. To a future sensor system, the same moment could contain a large amount of information. The system could register that someone entered the area in front of the display, stopped for 3.8 seconds, stood at a certain distance and directed their gaze towards two different areas of the image. It does not initially need to know who that person is. The information could simply be anonymous statistics. Yet it can still reveal a great deal about how people react to the content. For the advertising industry, this would be enormously valuable because companies would no longer only measure how many people pass a display, but how people actually react to what is being shown.

From Anonymous to Identified

The issue becomes more significant when information from different systems is combined. The digital retina does not need to identify a person by itself. The phone in their pocket may provide information. Wi-Fi, Bluetooth, a customer app, memberships, ticketing systems, payments and facial recognition could all add further pieces. Each system may know only a little, but together they could create a highly detailed picture. What begins as “a person looked at the advertisement” could later become “the same person returned two hours later” and eventually “we know who that person is.” When anonymous observational data becomes linked to identity, everything changes. Behaviour can then be followed over time, and profiles can be created in ways that go far beyond traditional camera surveillance.

When the Room Develops a Memory

We often think of surveillance as video recording. A camera records, the footage is stored, and someone can review it later. But future surveillance does not necessarily have to work that way. It could instead record events and patterns. When did the person arrive? How long did they stay? Which route did they take through the building? Which screens did they look at? How often did they return? The system does not need to save every second as video. It can save conclusions instead. In this way, the place develops a kind of memory. The shop remembers you. The office remembers you. The car remembers you. The screen remembers that you stood in front of it. The environment is no longer only physical. It also becomes digitally observant.

The Workplace That Looks Back

Perhaps the most immediate version of this idea can be found in the workplace. Many people spend most of their working day in front of a screen. If that screen can also function as a sensor, it could potentially detect when someone arrives at their desk, when they leave their chair, how close they are sitting to the screen, the angle of their head, how often their gaze moves away and how long they appear to remain active. Many of these functions could be beneficial. They might help improve ergonomics, adjust screen brightness, detect fatigue or make technology more accessible to people with disabilities. But exactly the same information could be used to monitor productivity, attendance and behaviour. How long was the employee actually sitting in front of the computer? How long was lunch? Was the person paying attention during the video meeting? The technology itself makes no moral distinction between these uses. The person or organisation controlling the system decides how the information is used.

The Real Change Is AI

A sensor without intelligence is relatively limited. It records light and movement, but it does not understand what it sees. AI changes the equation. When artificial intelligence is connected to the sensor, the system can begin interpreting what is happening. It can distinguish people from objects, recognise faces, follow movement, identify unusual behaviour and compare current activity with previous observations. This is why the sensor alone does not make future surveillance powerful. The real power lies in the combination of sensor, AI and databases. The sensor sees. AI interprets. The database remembers. Together, they form a system that can operate continuously without a human being sitting in front of monitors.

Surveillance Without a Control Room

The traditional image of surveillance is a control room with a wall of screens and a person trying to follow what is happening. That model is inefficient because humans quickly become tired and miss important details. AI can change this by alerting the operator only when something unusual occurs. A system could follow one person from sensor to sensor, compare movement patterns and detect that the same individual keeps returning to the same location. This could offer major security benefits. It could help detect falls, prevent accidents or identify dangerous situations. But exactly the same capability could also be used to control people. The scale of surveillance becomes far greater because it is no longer limited by how many humans can sit and watch screens.

From CCTV to Ambient Surveillance

We are accustomed to talking about CCTV, camera surveillance in clearly defined places. One camera is located here, another there. But the more important concept in the future may instead be ambient surveillance — surveillance built into the environment itself. The screen can see. The car can detect who is sitting inside it. The door knows who passes through. The phone knows the location. The watch records movement. Glasses can understand what the wearer is looking at. Each device only needs to know one small part. When the data is connected, a much larger picture emerges. There is no longer a single camera that represents the surveillance system. The entire technological environment becomes a network of sensors.

The Screens Are Already Everywhere

This is precisely why screens are so important in this context. We do not need to build an entirely new physical infrastructure to place millions of sensory surfaces around society. Screens are already everywhere — at airports, stations, hospitals, schools, offices, hotels, restaurants and in our homes. They are on our desks and in our pockets. If future displays gain sensor capabilities, the meaning of all these surfaces changes. What was once simply an information channel becomes a two-way relationship. The screen sends information to the person, while the person, consciously or unconsciously, sends information back.

The Positive Potential

It would be too simplistic to describe the digital retina only as a threat. The same technology could create many positive possibilities. Video calls could become far more natural if the camera function were integrated into the entire screen. A person could then look directly at the other person’s face while the system captures their gaze from the same area. Screens could enable gesture control without external cameras. They could allow people who cannot use a keyboard or mouse to control a computer with their eyes. They could detect if an elderly person falls or if a child moves too close to a dangerous area. In medicine, sensors integrated into displays could potentially be used for different forms of optical measurement. The technology itself is therefore not the problem. It could be enormously useful.

The Problem Is Who Controls the Sensor

The decisive question is instead who controls the sensor. If I own the screen, activate the function myself and control the information, that is one situation. If an employer, retailer, authority or advertising platform controls the same system, it is another. The moral meaning of the technology changes depending on the balance of power. Future privacy debates therefore cannot focus only on which sensors exist. They must also ask who has access to them, what data is collected and what decisions can be made based on that data.

A New Kind of Red Light

Perhaps we need to rediscover an old idea. Older video cameras often had a red light clearly showing that recording was taking place. REC meant that the camera was active. In a future where the screen itself can operate as a sensor, we may need an equivalent principle. When a screen is observing people, those people should be able to see that immediately. Not through vague terms and conditions or a tiny icon hidden in an operating system. There should be a physical and technically verifiable indicator showing when the sensor function is active. Perhaps it should even be impossible to activate the sensor without activating the indicator at the same time.

Sensor Off Must Mean Sensor Off

The same principle applies to the possibility of switching the system off. Today, software controls often tell us that a camera has been disabled. But the user has to trust the system. A future privacy standard could require physical disconnection. Sensor off would then not mean “the software says we are not using the sensor.” It would mean “the sensor has no electrical ability to collect information.” The difference may sound technical, but from a privacy perspective it is fundamental.

Consent Becomes More Difficult

The question of consent also becomes more complicated when sensors merge with public environments. We are used to digital services where we click “accept” before using them. But how would this work in a railway station or shopping centre? If you walk past a screen capable of analysing your face and your gaze, you have not actively chosen to use the system. You are simply present in the space. This makes it increasingly unrealistic to solve future privacy problems through long user agreements and small signs. People need to understand when observation is taking place without having to read legal documents.

When the Computer Disappears Into the Environment

There is also a broader technological perspective. The computer began as an obvious object. It stood on a desk. Then it became smaller and moved into the phone, the car, the watch and household appliances. Today, we no longer think about many of the computers surrounding us. They have disappeared into the objects themselves. The same development may happen with sensors. First, we could see the camera. Then the camera became smaller. Then it was hidden behind the screen. The next step may be for the camera to stop existing as a separate object altogether. Instead, the surface itself gains the ability to perceive.

A Digital Nervous System

This is why the concept of a digital retina is so interesting. The retina does not function alone. It is part of a larger system in which the eye detects, the nervous system transports information and the brain interprets what is seen. A future digital environment could function in a similar way. The screen becomes the retina. The network becomes the nervous system. AI becomes the brain. The database becomes the memory. When these parts are connected, we no longer have just a camera. We have a perceptual system capable of seeing, interpreting, comparing and remembering.

When the Building Starts to Know

Take the idea one step further. A building equipped with hundreds of screens and other sensors could understand how people move through it. It could know which rooms are being used, where people gather and which areas remain empty. This could be used for energy efficiency, security and better urban planning. But the building could also begin recognising individuals. When infrastructure becomes intelligent, we move from smart buildings to observing buildings — environments that do not simply respond to crowds but potentially to specific people.

The Question Is Not Whether the Technology Will Arrive

Much of the basic technology already exists in different forms. Sensors are being integrated behind and within displays, optical systems are becoming smaller and AI is becoming increasingly capable of analysing visual information. This makes it less interesting to ask whether the development is possible. The more important question is how it will be used. Historically, we have often built the technology first and discussed the consequences afterwards. With the digital retina, we have an opportunity to do the opposite. We can begin discussing the principles before such systems become invisible parts of everyday life.

The Right to Know When You Are Being Seen

Perhaps there should be a new digital right: the right to know when a machine is observing you. Not merely the right to read a privacy policy, but the right to understand the situation immediately. Is the sensor active? What is being recorded? Is the information anonymous? Is it stored? Is it connected to an identity? Who controls it? Future technological environments will need to answer these questions far more clearly than today’s systems do.

When Everything That Can Display Can Also See

We may be moving towards a strange shift. Throughout the history of the screen, the relationship has been simple. We look at the screen. The screen shows us something. But when display and sensor begin to merge, the relationship changes. The screen can still show us the world, but it can also begin observing our reaction to the world it displays. This creates a new kind of feedback loop in which humans are no longer only recipients of digital information but also a continuous source of information.

The Decisive Boundary

There is therefore a boundary more important than the technology itself. It lies between knowing that you are being observed and no longer being able to know when observation is taking place. As long as the camera has a visible lens, we can at least understand that surveillance is possible. When the sensor becomes an invisible property of the screen, wall or room, that intuitive understanding disappears. Surveillance can then become something that simply exists, like lighting or ventilation.

When the Screen Looks Back

The digital retina could become an extraordinary tool. It could create better communication, smarter assistive technologies, safer environments and entirely new ways of interacting with machines. But it could also create a society in which observation becomes so deeply integrated into everyday life that people no longer know when they are being watched. That is why the discussion must begin long before every screen gains this capability. The question is no longer only what we can see on the screen. The question is what the screen can see in us — and perhaps even more importantly, who is allowed access to what it sees. When every surface can potentially become a sensor, we are no longer the only ones looking into the digital world.

The digital world begins to look back.