# Checkerboard Calibration

Note: If you haven't done the checkerboard calibration, the Focus live feedback will display the Focus Metric, which helps you to determine the best focus score for your image. The closer the score is to the Max value, the closer the focus is to being ideal.

Checkerboard calibration is an optional calibration that is recommended for images with noticeable lens distortion. This is normally the case when using wide angle lenses. It removes distortion from the image and should be executed before recipe features are trained.

Executing the checkerboard calibration can take several minutes, depending on the number of checkers in the fov of the camera and the camera model. Typical execution times are ~1 minute on AS8xx and ~4 minutes on AS2xx.

Checkerboard calibration requires a checkerboard calibration plate with L-shaped calibration fiducial. The fiducial must be fully in the fov of the camera.

Note: When attempting to run checkerboard calibration on an inappropriate image (no checkerboard), this may take a very long time and the HMI can freeze. Even manual power cycle of the camera may be required.

Steps to perform the calibration:

1. Select the camera
2. Bring calibration plate in fov of the camera.
3. Set up exposure for good contrast.
4. Enter checker size in mm
5. Press Calibrate button.
6. A MessageBox will be shown when calibration has finished.

Note: The checkerboard calibration at runtime will add 20…80ms to the cycle time, depending on camera model.