Have you noticed? Images captured by machine vision systems sometimes exhibit subtle deviations from the actual objects— incorrect dimensions, misaligned positions, or distorted shapes. The culprit behind these issues is likely lens distortion. It operates silently yet directly impacts the efficiency and accuracy of industrial vision systems.

What is lens distortion?

Lens distortion refers to the discrepancy between the captured image and the actual object. It is most pronounced at the edges of the image, where object boundaries may appear stretched or compressed, with shapes distorted.

In industrial applications, such distortion can introduce errors in automated inspection, robotic grasping, and even object recognition tasks. Therefore, understanding and correcting it is a critical challenge for every industrial vision engineer.

What are the types of lens distortion?

Industrial lens distortion primarily falls into two categories: pillow-shaped distortion and barrel-shaped distortion.

Pincushion distortion

Manifestation: The four corners of the image converge toward the center, with concave edges resembling a pillow.

Commonly found in telephoto lenses, especially the zoom telephoto end.

Impact: Object edges appear smaller, and edge detection accuracy decreases.

Barrel Distortion

Performance: The image corners bulge outward, resulting in a barrel distortion.

Commonly found in: wide-angle lenses or wide-angle zoom lenses.

Impact: Object edges become stretched, making it easier to misjudge position and shape.

How does distortion affect industrial vision?

inaccurate dimensions: deformation of object edges increases measurement errors.

Position deviation: An error occurs during the grasping or positioning task, affecting operational accuracy.

Shape distortion: Detection results based on shape recognition may be unreliable.

In short: Distortion compromises the accuracy of originally precise machine vision systems.

How to correct lens distortion?

1. Use a high-quality lens

High-quality industrial lenses address distortion issues during the design phase. This is particularly true for wide-angle and telephoto lenses; products with optimized designs naturally exhibit minimal distortion.

2. Software Correction

Modern machine vision systems are typically equipped with distortion correction algorithms. By analyzing lens characteristics, the software can automatically or manually adjust images to approximate the actual shape and position of objects.

3. Reasonably adjust the focal length and shooting angle

Avoid extreme focal lengths, especially at wide-angle or telephoto ends. A minor adjustment can significantly reduce the impact of distortion on high-precision detection.