Measurement of Fe and Mn concentrations using image processing techniques based on color intensity approachPutri Sandi Daniar, Yuniati Zevi, Rijal Hakiki, Barti Setiani Muntalif and Rahmatun MaulaE3S Web of Conf., 485 (2024) 04012DOI: https://doi.org/10.1051/e3sconf/202448504012