In high-speed textile inspection, maintaining image quality while dealing with fluctuating material speeds is a major challenge. One of our clients recently shared a detailed case using the LEO 8192G-L14gc line scan camera, highlighting the complexity of synchronizing line rate with encoder feedback in real-world production.
Real-World Challenge:
The customer's requirement was straightforward—but technically demanding:
Allow the line scan camera to dynamically adjust its line rate based on the real-time speed from an encoder, without manual intervention.
Currently, the line rate is manually set on the camera, making it unsuitable for variable-speed environments. The challenge is to make the camera “listen” to the encoder and react accordingly.
Hardware Setup:
Camera: LEO 8192G-L14gc (8192 px, GigE)
Encoder:
- Supply: 4.75–30V DC
- Output: Differential A/B/Z channels, push-pull
- Resolution: 250 PPR
- Measurement wheel: 250 mm (1 mm = 1 pulse)
- Max frequency: 200 kHz
- Encoder’s A+/A– and B+/B– channels are wired directly to the camera’s IO lines, but powered independently.
Calibration Procedure & Issues Faced:
Initial Steps:
- A white paper was placed over the textile material within the camera’s field of view.Automatic PRNUC (Photo Response Non-Uniformity Correction) and white balance calibration were performed
- Camera illumination was aligned to the brightest region of the textile surface.
Problems Encountered:
Despite calibration, the team encountered persistent visual artifacts
Vertical Stripes: Seen in both preview (6-pixel line mode) and full captures, these artifacts were consistent across mono and color modes.
Color Fringing: Especially at fabric color transitions, red-blue halos appeared. While tuning line rate reduced horizontal striping, vertical fringing remained.
Possible Cause:
- Paper used for PRNUC didn’t fully cover the field of view—green axis lines (machine parts) remained visible during calibration.
- The partial coverage potentially corrupted the PRNUC result, leading to artifacts.
- Misalignment between encoder and camera timing may also contribute.
Next Steps & Recommendations
- A new sample is being prepared to shoot a standardized PRNUC video tutorial for the client.
- Client was advised to perform a factory reset calibration or ship the camera back for tuning if artifacts persist.
- Long-term solution: Enable real-time encoder-to-line rate synchronization, either via firmware updates or through external trigger-based acquisition.
Conclusion
- This case underscores the critical need for dynamic line rate adjustment in textile inspection systems. While the LEO 8192G-L14gc excels in resolution and frame quality, unlocking full encoder-based synchronization remains key for fast-moving, variable-speed inspection lines.
- If you’ve encountered similar challenges or want help integrating encoder-based control into your vision system, get in touch—we’re happy to support.