'through posters' is correct and usable in written English.
You can use it when you are discussing a method of communication or advertising. For example: The company promoted its new product through posters in several public places.
Through posters, the "Little Red Book" and re-education circles, his message was constantly reinforced.
We worked on them together through posters and pictures, and gradually the problem stopped.
Men and women, aged 18 60 years, were recruited through posters, emails and mailshots.
Professional artists would descend on Tower Hamlets and inspire residents through posters on advertising hoardings.
Cornell students shared their global experiences through posters April 15 at the 2019 Community Engagement Showcase.
Through posters and meetings with student leaders, university officials urged students today "not to do anything excessive or emotional".
The final recommendation is that job centres make clear through posters that volunteering does not necessarily affect entitlement to benefits.
The French popularization of photography through posters and postcards was one of the most remarkable cultural events of the late 20th century.
It came well into editing, and only after the studio had introduced Mr. Ledger's Joker through posters, trailers and a six-minute Imax short.
The experience helped us to consider different ways of bringing the "without limits" brand idea to life through posters and other formats.
It appears that the people were open to persuasion and the ministry's slogans, promulgated through posters and in compliant newspapers, became part of the nation's conversation.
