Comparison
Line Scan vs Area Scan
The product's motion decides this, not the defect. Continuous surfaces want line scan; discrete parts want area scan.
Direct answer
When is line scan better than area scan?
Line scan is better when the surface is continuous or endless (web, film, coil, extrusion) or when very high resolution is needed across a wide surface, and reliable encoder motion feedback exists. Area scan is better for discrete parts at a station, where a single triggered frame captures the whole inspection and synchronization complexity can be avoided.
Comparison
- Product motion
- Line scan: continuous; Area scan: indexed or spaced parts
- Resolution scaling
- Line scan scales across width cheaply; area scan needs more cameras
- Synchronization
- Line scan requires encoder clocking; area scan needs only a trigger
- Lighting
- Line scan needs intense uniform line light; area scan can strobe
- Integration risk
- Line scan higher; area scan lower
- Data volume
- Line scan continuous stream; area scan bounded per part
Common mistake in both directions
- Using area scan on a continuous web: gaps, stitching artifacts and unreliable defect position.
- Using line scan on discrete parts: unnecessary encoder integration, harder lighting, no benefit.
- Ignoring the encoder quality: a slipping or low-resolution encoder ruins line-scan geometry.
A quick sizing example
A 600 mm wide web requiring 0.1 mm per pixel needs 6,000 pixels across the width — one 8k line-scan camera comfortably covers it. Achieving the same with area-scan cameras at similar resolution would require several cameras plus overlap management, all synchronized, at higher cost and more calibration surface area.
Frequently asked questions
- Can I inspect a cylindrical part with line scan?
- Yes — rotate the part under the sensor with encoder feedback and the sensor effectively unwraps the surface. This is a common approach for bottles, cans and rolls.
Related engineering material