Is my work in a printing press that sometimes prints semi-nude pictures, even though my work is manual and has nothing to do with printing, considered Haram? And is the money I earn from this work considered Haram?

Assisting in the unlawful is unlawful. If your primary job at the printing press is to print scientific and economic journals, and your work is limited to only the permissible aspects, with no involvement in printing popular magazines that contain semi-nude pictures of women, then there is no harm in you staying. However, it is more scrupulous to leave it and seek another job. But if your work is mixed with the unlawful and supportive of it, then it is not permissible to continue in it unless you are compelled, in which case you must seek another job. As for the salary earned from an unlawful past job, there is no harm in using it if you were ignorant of its unlawfulness and have repented to Allah, citing the noble verse: "So whoever receives an admonition from his Lord and desists, he may have what has already passed, and his affair is left to Allah."