Line Scan Cameras

A line scan camera is an industrial imaging device that captures images one line of pixels at a time instead of acquiring a full frame in a single exposure. A line scan camera uses a single line of pixel data to build up a two-dimensional image, which allows detection of small defects at high speed.

A line scan camera is ideal for continuous inspection and high-speed industrial imaging applications, including web inspection, conveyor-based inspection, semiconductor inspection, electronics inspection, and surface inspection. It is widely used for paper, plastic film, and metal sheet inspection, as well as food sorting, wafer inspection, PCB inspection, and print defect detection. Line scan cameras also excel at identifying coating irregularities and surface flaws and are well suited for high-resolution imaging of large objects such as wood panels and solar panels.

The line scan camera continuously captures individual lines of pixel data, which can either be analyzed in real time as they are acquired or reconstructed by software into a complete 2D image for further processing.

To form this full image, relative motion between the camera and the object is required. This is typically achieved by moving products on a conveyor belt or rotating them on a stage. As the object passes the sensor, the camera records sequential lines that are combined to create a two-dimensional image.

Color line scan cameras create full-color images by capturing separate red, green, and blue channel data using one of three technologies: bilinear, trilinear, or prism-based designs.
Bilinear and trilinear cameras use color filters directly on the sensor lines to capture RGB information. Bilinear models use two lines and reconstruct color through interpolation, while trilinear models use three dedicated lines (R, G, and B) that are digitally aligned as the object moves.
Prism-based cameras, in contrast, use a beam-splitting prism to optically separate incoming light into red, green, and blue components before directing them to three aligned sensors. This enables simultaneous color capture at the same spatial position and delivers the highest color accuracy.

Line scan cameras are most effective when you need to inspect long, continuous items, or a variety of items that have many different lengths or sizes. When the object does not have a well-defined start, end, or even size to it, a line scan camera is most suitable for your application. Because they operate continuously, line scan cameras have a vertical resolution that is effectively “unlimited” and can easily construct two dimensional images with much greater total resolution. 

An area scan camera, on the other hand, is typically used when the items that are being inspected, sorted, or analyzed have definite shapes or boundaries. 

For a more detailed explanation and side-by-side examples, see our line scan vs. area scan camera comparison.

From the earliest line scan imaging systems to today’s high-speed, high-resolution cameras, a lot has changed. Discover the key milestones and technologies that shaped the evolution of line scan imaging.