Perspective cropping in Photopea¶

As one of the final preprocessing steps, you'd want to crop the photo such that it only has the relevant contents of the photoquadrat, removing the quadrat itself and anything outside it. You'd typically do this as the last step of preprocessing, after color correction and lens correction.

This page describes perspective cropping, which is the most accurate. Another way to crop is square cropping.

Please read perspective cropping in Photopea, which is basically the same steps.