poster
Use poster if the entire image by itself is a poster. (See post #8686)
This can be a scan (post #6996), a photo (post #294646), or made-up (post #152523).
Use poster_(object) when a poster is present in the given image, but the uploaded image is not a poster. This is usually pasted/hanged on the wall. (See post #10648, post #38736)
In some cases, an image can be tagged both poster and poster_(object). (See post #775810)