Options to set trimming threshold are not yet merged in main branch - they are available only in dev branch.
Both trimming attempts examine variance of the image bands and continue cutting until variance reach the threshold. Simple but effective method implemented by Mangle author.
https://github.com/ciromattia/kcc/bl.../image.py#L319
https://github.com/ciromattia/kcc/bl.../image.py#L372