Intelligent security systems – Part 4 of 6

How to choose lighting for container recognition systems

Raytec is a world leader in LED lighting for security and safety applications. In this article Callum Ryder, market manager, his views on lighting requirements for a container recognition systems (CRS).

Container recognition systems use an automated system that utilises intelligent image processing to identify, check, and store a series of numbers, letters or barcodes that normally appear on the top, or side, of a container. The system will then store the information and use it to direct operations on-site and control the movement of goods. Some systems also capture the license plate of the vehicle carrying the container.

Container recognition systems operate often 24 hours a day and ambient light alone is not sufficient to provide the camera with high-quality images day and night. Poor, variable and changing weather conditions, which significantly affect the quality of the image that a camera can obtain, is another challenge.

“Unclear and inconsistent images may lead to incorrect data, producing errors within the system. This may result in containers becoming lost, or cause delays,” states Callum Ryder, who also emphasises that lighting helps to ensure highquality, consistent images of the information on the side or top of the container and is a vital cog in the reliability of the entire system.

850nm Infra-Red (IR)

When specifying lighting for a CRS, one of the first considerations is the wavelength of light which will be most suitable for the system.

850nm Infra-Red (IR) is commonly used within container recognition applications. Cameras are most receptive to this wavelength of IR enabling them to support the best night-time images. IR is ideal for capturing the detail of a container number or barcode. Being semi-covert, an 850nm illuminator gives off a slight red glow, but this is only visible up close, or when looking directly into the light, and generally is not a cause of concern when used for container recognition.


While 850nm IR may provide the best results for capturing the container number or barcode, many systems may have other lighting goals, which require colour images to be captured and damage identified. Then use of White-Light can provide a greater level of detail and increase the performance of the analytics software used to identify issues.


For systems which are also looking to illuminate inside the vehicle carrying the container, 730nm provides the best results for seeing through a vehicle’s windscreen and supports driver and passenger recognition which may be running in tandem with the container recognition system.

“However, we’d only recommend the use of 730nm if there’s a need for the illuminator to provide a dual use of container recognition and driver recognition,” comments Callum Ryder.

Constant vs. Pulsed

Specifiers must also decide between using either constant or pulsed illumination. Constant Illumination means that the light is switched on 100% of the time. It is generally used when the vehicle is stationary or moving at lower speeds. While each application should be judged on an individual basis, it is less common for container recognition systems to encounter issues with motion blur, or other challenges associated with capturing images with higher-speed applications. One of the benefits of using constant light is the easier set-up compared to pulsed.

Pulsed Illumination

Pulsed (or strobe) illumination is used to provide on-demand lighting to accurately record images of fast-moving objects. A pulsed illuminator is designed to sync directly with the camera’s shutter via a digital input. The increase in power that pulsed illumination provides can also help overcome issues such as challenging weather conditions and glare.

Avoiding Overexposure

Many applications suffer from overexposure to the container number or barcode. It generally occurs when the camera and illuminator are too close to the object or area in question. This generally causes a large white spot on the image. If the code is unclear, the system cannot work effectively and would likely lead to errors or inefficiencies.

Harsh Environments

Container storage sites are generally located in coastal areas where high levels of wind and rain are commonplace. This poses a challenge to capturing high-quality images, which means that the environmental protection of the illuminator is of highly importance. Raytec’s Vario2 Extreme illuminators are rated (IP67 and IK09) for use in the harshest environments and operating conditions. Their extreme salinity and humidity protection, make them an ideal lighting solution for marine applications.


It also important to consider how the illuminator in a CRS can be controlled, and how it can communicate with the system’s other devices. In many systems, the lighting is only activated during vehicle passage, helping to create smart, situational dependent lighting, which is far more efficient. For this reason, specifying an illuminator that is IP enabled so it can be connected to other devices via an ethernet connection is always a good option.


A good quality image for a container recognition system includes sharpness, spatial resolution and high contrast of the characters, as well as good positioning and an optimal viewing angle. Testing the final solution is extremely important. “The more testing that can be done before full deployment the greater chance of achieving highquality, reliable images”, concludes Callum Ryder.

Note: This editorial article has primarily been produced for the security trade magazine Detektor in collaboration with

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