How to open PDF on Linux (Ubuntu) and see DPI of pictures inside?

Question

linux

Can you please tell me how to open a PDF on Linux or parse a PDF and see the DPI of the pictures in it? Or if this is not possible, then how can you "gut" a PDF and then see the DPI of the pictures. Ideally, if there is a similar gem for Ruby.

Answer 1

man pdfimages
Yes, with identify you can get information about the size of an image and so on.