OpenVPCal Plugin - Best Practice

This page provides best practices to achieve optimal colour calibration results with the OpenVPCal Plugin. Following these recommendations will help you avoid common issues and ensure reliable, high-quality calibration results.

Hardware Setup

Proper hardware setup is critical for achieving accurate colour calibration results. The calibration process uses the camera as a colourimeter, so precise configuration of both camera and LED wall settings is essential for reliable calibration data.

LED Wall Configuration

1. Warm up LED panels - Display a flat grey colour for 20-40 minutes before capture and note physical temperature (most Image Processors should provide this figure).
2. Set LED processor to PQ (ST2084) - Strongly recommended over sRGB for better calibration accuracy.
3. Configure custom gamut settings on LED processor to match wall primaries if using custom target gamut. Make sure this is reflected in the Add Custom Gamut section of the Settings Tab.
4. Check Legal vs Full range settings - Ensure consistent video data range throughout the pipeline. Use the Data Range Verification SPG pattern to verify. See Data Range Verification for the complete instructions.
5. Set LED panels to maximum gain allowed by the image processor calibration (do not override).
6. Turn off unused LED sections to avoid flare from panels not directly in front of the camera. Remove any additional potential disturbances/occlusions.

Camera Configuration

To ensure the best camera configuration, follow these instructions aided by those provided on the first generated patch.

1. Use the production camera - Use the same camera model and firmware that will be used in final production to avoid any discrepancies after calibration.
2. Set exposure to 18% using the camera’s false colour tool - the centre grey square should hit 18% of camera sensitivity. Use the 17% and 19% reference patches to fine-tune.

3. White balance settings:
   • Auto white balance if Auto WB Source is enabled in the plugin settings.
   • Otherwise set to 6500K (LED wall white point) or manual white balance to the centre grey square.
   • No tint adjustment - keep tint settings neutral.
4. Use no additional exposure adjustments - If your camera has additional exposure controls aside from the traditional ones, ensure they are zeroed before proceeding.
5. Use a clean prime lens (35-65mm focal length recommended).
6. Defocus slightly to prevent moiré - focus just in front of the panel (rather than behind), just enough to blur the edge lines of the centre square.
7. Use an appropriate t-stop (T4-T8 range) matching production requirements.

Capture Setup

1. Position camera flat to wall - Ensure centre grey square covers 60-70% of vertical camera field of view.
2. Centre camera on wall using first patch alignment guides.