There is no resolution associated with a PDF file. A PDF file can contain text, vector graphics and images. Text and vector graphics do not have any resolution associated with them, they are by definition rendered at the output device resolution. Only bitmap images have a resolution, but every image can have a different resolution. So in order to find out what the resolution of a PDF is, you need to extract the information for all bitmap images in the file. The Preflight tool in Acrobat Pro can do that.
Karl Heinz Kremer
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