I am printer. Is it allowed for me to help people make posters containing pictures of living things by scanning or any means?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the things advertised are from what people necessarily need and if using pictures to make posters is necessary to help understand these things, then there is no harm in doing that. But one should stick to the minimum necessary. This rule is about photographic pictures.

As for the pictures you draw yourself or by using a computer, the rule about these is more restricted as they are clearly forbidden in the Sharee’ah. So, it is not lawful to draw an entire picture of a person or an animal, or to help in doing that unless that picture lacks a vital organ (like the head) without which it cannot be considered a picture of a living being.
For more benefit on the prohibition of drawing living beings, please refer to Fataawa 90288, 82806, and 336841.

Allah knows best.