Line Scan vs Area Scan Camera: Differences and When to Use Each
A roll of plastic film runs continuously through an inspection station, with no stops and no individual “parts” to photograph. A beverage can needs its label checked around the full circumference. A glass panel is longer than any single camera’s field of view. Problems like these start to stretch an ordinary camera, and that is usually when a line scan camera appears in the quote. This guide explains the difference between a line scan vs area scan camera, which applications suit each, what a line scan system needs to work well, and includes a worked example and a checklist to help you choose.
If you are new to machine vision, start with What is machine vision? for an overview of the components in a vision system. This article focuses on one specific choice within the camera itself.
What is an area scan camera?
An area scan camera uses a two-dimensional sensor array and captures the whole frame in a single exposure, much like a photo camera. It is the most common camera type in machine vision and sits at almost every inspection station for discrete parts.
With a global shutter sensor, where every pixel is exposed at the same moment, an area scan camera can image a moving part without distortion. The Basler ace 2 family is a typical example; see our industrial cameras page or the Basler a2A4012 model.
When area scan is the default choice
- Discrete parts with a defined size: components, circuit boards, bottles, boxes, machined parts.
- Stop-and-go or slow lines: the part stops, or passes the imaging position slowly enough not to blur.
- Several inspection regions in one image: checking a label, reading a code and measuring a distance in the same frame.
- Robot guidance, presence checks and assembly verification.
Its biggest advantage is simple integration: standard lenses, lights and mounts, with no need to synchronize to conveyor speed.
What is a line scan camera?
A line scan camera uses a sensor made of a single row of pixels, or just a few rows. Each time it is triggered, the camera captures one very thin line. As the object moves past the camera, thousands of consecutive lines are stitched together into a two-dimensional image. In other words, the second dimension of the image comes from the object’s own motion.
Because there is only one row, a line scan camera can pack a very large number of pixels into each line, giving high resolution across the width, while the image length is practically unlimited. The Basler racer family is an example, with models such as the raL6144-16gm and raL12288-8gm (the first number in the model name is the number of pixels per line). Browse the line scan cameras that BeeVision supplies.
When a line scan camera makes sense
- Continuous web materials (web inspection): paper, film, foil, textiles and nonwovens.
- Long or very wide objects: glass panels, metal sheets and plates, solar panels, large circuit boards.
- Cylindrical surfaces that need full-circumference inspection: cans, bottles, pipes and rollers. The part rotates in front of the camera and the image “unrolls” the curved surface into a flat one.
- High resolution over a wide area that an area scan setup could only match by splitting the view across several cameras.
- High line speeds where an area scan camera struggles to capture a sharp image without very powerful strobe lighting.
Line scan vs area scan camera: side by side
| Criterion | Area scan camera | Line scan camera |
|---|---|---|
| Sensor | 2D array, captures a full frame | One or a few pixel rows, stitched line by line |
| Motion | Not required | Continuous relative motion is required |
| Synchronization | Trigger from a sensor or PLC | Usually an encoder to match conveyor speed |
| Lighting | Ring, dome, backlight, low-angle and more | Line lights, bright and uniform |
| Field of view | Limited by the sensor | Practically unlimited along the direction of motion |
| Integration | Simple, standard components | More involved: mechanics, encoder, lighting, data bandwidth |
| Typical fit | Discrete parts, multiple regions, robot guidance | Webs, long parts, cylinders, wide high-resolution areas |
For most discrete-part inspection stations, an area scan camera is still the sensible starting point. A line scan camera is worth considering when the application shows at least one of the signs in the right-hand column.
What does a line scan system need?
Line scan cameras are powerful, but they only deliver good images when the whole system is designed together. These four factors usually decide success or failure:
1. Encoder and line rate
The camera has to capture each line exactly when the object has moved by one pixel’s worth of distance. If the conveyor speeds up or slows down while the camera keeps a fixed rhythm, the image gets stretched or squashed. That is why line scan systems typically use an encoder, a rotary sensor mounted on the conveyor shaft, to trigger lines by distance travelled rather than by time.
2. Bright line lighting
Each line has a very short exposure time, so line scan needs more light than area scan. A line light concentrates illumination onto the narrow strip the camera sees, and it must be uniform across the full width. Manufacturers such as OPT Machine Vision offer line lights and other specialized lighting; see our OPT Machine Vision page.
3. Stable mechanics
The material must pass the camera smoothly, without vibrating or drifting out of the focal plane. For cylindrical parts, the object needs to rotate evenly through exactly one turn while it is imaged.
4. Bandwidth and processing
High-resolution line scan cameras produce a very large, continuous data stream. Plan the interface (GigE, CoaXPress, Camera Link and so on), the frame grabber and the processing power early, which usually means a PC-based vision system. Our article Smart camera vs PC-based vision explains why.
A quick worked example: a film line
Suppose you need to inspect a film web 500 mm wide running at 60 m/min, and you want each pixel to cover about 0.1 mm on the material. The figures below only illustrate how the calculation works.
- Pixels per line: 500 mm ÷ 0.1 mm = 5,000 pixels. A camera with around 6,000 pixels per line, such as the raL6144, is enough and leaves margin at the edges.
- Conveyor speed: 60 m/min = 1,000 mm per second.
- Required line rate: 1,000 mm/s ÷ 0.1 mm = 10,000 lines per second, or 10 kHz. The camera must reach this rate, and the encoder must deliver pulses fine enough to trigger each line.
Note that a 0.1 mm pixel does not mean you can detect a 0.1 mm defect. In practice a defect usually needs to span several pixels and show enough contrast under the chosen lighting. That is why the calculation is only a starting point, and the conclusion has to come from testing real samples.
Checklist: which camera fits your application?
- Is the product made of discrete parts, or is it continuous material? Discrete leans towards area scan; continuous leans towards line scan.
- Is the object longer or wider than a sensible field of view for one area scan camera?
- Do you need to inspect the full circumference of a cylindrical part?
- Does the line stop at the imaging position, or run continuously at high speed?
- Can you fit an encoder and keep the material moving steadily past the camera?
- Do you need to look at several different regions on a part, or scan one large surface evenly?
If most answers point to “discrete parts, stopping or slow, several inspection regions”, an area scan camera is the simple and effective choice. If they point to “continuous, long, wide, cylindrical”, evaluate a line scan camera.
How BeeVision helps you choose
BeeVision is an authorized distributor of both area scan and line scan cameras from Basler, together with OPT Machine Vision lighting and lenses, industrial PCs and software. For line scan applications, our engineering team designs the camera, line lighting, encoder and processing system as one package, and BeeVision’s in-house R&D/AI team can tailor the BeeVision Studio software to your line and connect it to your PLC, MES and ERP.
The surest way to decide is still to test on real samples: send us a length of material or a few parts with real defects, and our engineers will build a trial setup and tell you which camera and lighting can catch your defects. BeeVision engineers provide on-site support across Vietnam, in both Vietnamese and English. For a manufacturer’s perspective, Cognex has a useful article on line scan vs area scan.
Key takeaways
An area scan camera captures the whole frame at once, is simple to integrate, and is the default choice for discrete parts. A line scan camera builds the image line by line as the object moves, and excels with webs, long parts, cylindrical surfaces and wide areas that need high resolution, but it requires an encoder, line lighting, stable mechanics and enough processing power. Choosing the right camera type from the start helps you avoid projects that capture images but still miss the defects.
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Send us your samples: we test on real parts before you invest. We will tell you whether an area scan or a line scan camera is the better fit for your line, based on real test results.
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