Lighting for video surveillance

A camera can only record what light shows it. The most common reasons night footage is useless are not the camera itself but the lighting: faces in shadow, bright lights behind the subject, glare into the lens, dark gaps between fixtures and infrared that does not reach far enough. Designing the lighting and the cameras together fixes most of these before they happen.

Why cameras struggle with poor light

A camera sensor turns light into an image. When there is too little light, the camera compensates by amplifying the signal, which adds grainy noise, and by keeping its shutter open longer, which blurs anything that moves. The result is footage where a person is visible but their face, clothing details or a licence plate are not. Compression makes this worse: noisy images use more storage and the encoder throws away detail to keep up.

Lighting that looks fine to a person can still be poor for a camera. Our eyes adapt over minutes and handle a wide range of brightness in one scene; cameras handle a narrower range and adapt in fractions of a second, often badly. So the questions are not only how much light there is, but where it comes from, how even it is and what else is in the picture.

Backlighting and glare

The single most common problem is a bright background behind the subject. A camera inside a lobby looking out through glass doors in daylight, or a camera at night facing a lit parking lot from a dark corridor, sets its exposure for the bright area and turns everyone in front of it into a silhouette.

Light the face, not the background. On the left, the camera looks towards bright glass, sets its exposure for it and leaves the person in silhouette. On the right, light comes from near the camera's side and falls on the face, with a darker background behind.

The fixes, roughly in order of effectiveness:

Position cameras so they look away from bright windows, doors and fixtures, for example looking into a building entrance from outside rather than out through it.
Add light on the subject's side so faces are lit from the front, with vertical light at face height rather than only downlights from directly above.
Keep fixtures out of the camera's view, and especially out of its line of sight at night, when a single bright fixture can flare across the image.
Use cameras with wide dynamic range for scenes that cannot be avoided, accepting that it reduces the problem rather than removing it.

Even light and vertical light

Cameras need the same thing people need from site lighting: even coverage without deep shadows. A camera covering a parking lot with bright pools under each pole and dark gaps between them will lose people in the gaps, and its exposure will hunt as they walk in and out of the light. Our guide on exterior and security lighting covers how to achieve even coverage.

For identification, light on vertical surfaces matters more than light on the ground. A lighting design that meets its target on the pavement can still leave faces dark. Where cameras are meant to identify people, at entrances, reception counters, cash areas and gates, specify vertical light at face height in the direction the camera looks. Our guide to camera placement and pixel density explains how identification zones are planned.

Infrared illumination

Many cameras include infrared illuminators, invisible to people, and switch to a black-and-white mode at night. Infrared is useful where visible light is unwanted or impractical, but it has limits that are easy to miss:

Built-in illuminators have a limited range, so the far part of the field of view can be dark even when the near part is bright.
Nearby surfaces, such as a soffit, wall or the camera's own housing, can reflect infrared back into the lens and wash out the image.
Insects and spider webs near the lens glow in infrared and can trigger motion detection all night.
Infrared images do not show colour, so clothing and vehicle colour cannot be recorded.

Where infrared runs out. The camera's built-in infrared lights only the nearer part of its view, leaving a dark band beyond it. A pool of site lighting further out fills the far area, while the gap between them stays too dark to use.

Separate infrared illuminators can extend range and are mounted away from the camera to reduce reflection and insect problems. On sites where white light is acceptable, ordinary lighting designed with the cameras in mind is usually more useful, because it also helps people on site and gives colour images.

Day, night and colour

Most cameras switch from colour to black and white when light falls below a threshold. Whether that happens depends heavily on the site lighting.

Colour at night depends on the lighting. Without enough site light, the camera switches to black-and-white infrared at dusk. With lighting designed for it, the same camera can keep recording in colour, which preserves clothing and vehicle colours.

Colour rendering also matters. Sources with poor colour rendering, such as older high-pressure sodium lighting, make colours hard to tell apart even when there is plenty of light. Modern LED fixtures with good colour rendering help, and keeping a consistent colour temperature across an area avoids colour shifts as people move between fixtures.

Flicker and controls

Some LED drivers flicker at a rate the eye cannot see but a camera can, producing rolling bands or pulsing in the image. Specify low-flicker drivers for areas covered by cameras and check footage during commissioning. Lighting controls also need coordinating: lights dimmed to a low overnight level, or switched by motion sensors, can drop below what the camera needs, and a motion-triggered light that comes on only when someone is already close may be too late to capture their approach.

A night walk test

The only reliable check is to look at live footage at night with someone walking through the scene. A simple procedure:

Choose the night conditions you care about: lights at their overnight level, after closing, with and without snow if possible.
Have a person walk set routes through each camera's view, stopping at identification points such as doors and gates.
Watch the live image and the recording, since compression can hide detail visible on the live view.
Record for each camera whether the person can be detected, recognised and identified at each point, and note glare, dark gaps, noise and infrared reflections.
Agree fixes, such as re-aiming, added fixtures, shields or camera changes, and repeat the walk after they are done.

How ehZee can help

We design site and building lighting with the camera plan in mind, review night footage and lighting on existing sites, and coordinate lighting, controls and camera choices so they work together. Drawings for permit are sealed by a licensed professional engineer where required, and installation is done by licensed electrical contractors under permit. See our lighting design and controls service, and video surveillance design for the camera side.

Common questions

Can a better camera fix poor lighting?

Partly. Cameras with larger sensors, better low-light performance and wide dynamic range help, but they cannot create detail that the light does not reveal. Fixing the lighting usually improves every camera on the site at once.

Should we use infrared or white light?

Where light pollution, neighbours or covert monitoring matter, infrared is useful. Where people also use the area at night, white light designed for the cameras is usually the better investment, because it helps people and gives colour images.

When should lighting and camera design be coordinated?

As early as possible, ideally when fixture and camera positions are first laid out. Moving a pole or adding a wall fixture on paper is cheap; doing it after the parking lot is paved is not.