What is the ruling on installing pictures of Muslims in an unfitting manner, and what is our duty towards those who do so?

Preserving the honor of Muslims is an obligation, and harming them and violating it is forbidden by Islamic law, for Allah Almighty says: "And those who harm believing men and believing women for [something] other than what they have earned, have certainly borne a slander and a manifest sin." And for the saying of the Prophet, peace and blessings be upon him: "Every Muslim's blood, property, and honor are sacred to another Muslim." So, whoever knows of such an act, it is obligatory for him to condemn the perpetrator and warn him of Allah, and if he does not desist, then he should report him to the responsible authorities.