Use convert to grab a specific page from a PDF file?

Question

I know I have done this before, so I'm sure it's possible, I just forget how to do it. There's a way to tell convert to grab a specific page of a PDF, and I'd like to keep the format of that page as PDF.

Answer 1

ImageMagick is a tool for bitmap images, which most PDFs aren't. If you use it, it will rasterize the data, which is often not desirable.

Pdftk can extract one or more pages from a PDF file.

pdftk A=input.pdf cat A42 A43 output pages_42_43.pdf

If you have a LaTeX installation with PDFLaTeX, you can use pdfpages. There's a shell wrapper for pdfpages, pdfjam.

pdfjam -o pages_42_43.pdf input.pdf 42,43

Another possibility (overkill here, but useful for requirements more complex that one page) is Python with the PyPdf library.

#!/usr/bin/env python
import copy, sys
from pyPdf import PdfFileWriter, PdfFileReader
input = PdfFileReader(sys.stdin)
output = PdfFileWriter()
for i in [42, 43]:
    output.addPage(input.getPage(i))
output.write(sys.stdout)

Answer 2

You can use subscript notation with convert(1) to "index" into a PDF:

$ convert source.pdf[1] dest.pdf 

The index value depends on how the PDF exporter numbered the pages. In tests on files here, the numbers seem to be zero-based, so the above example gets you the second page in the document. I've seen examples online where they show letter indexes instead, since apparently the PDF creator "numbered" the pages in that document that way instead.

Unfortunately, this doesn't give very good results, because ImageMagick assumes everything is pixel-based, and therefore rasterizes vector imagery, such as the typography in a typical PDF.

A better tool for the job is Ghostscript, which you probably already have installed:

$ gs -dNOPAUSE -dBATCH -dFirstPage=2 -dLastPage=2 -sDEVICE=pdfwrite \
    -sOutputFile=dest.pdf -f src.pdf

This passes the PDF data through unchanged, since Ghostscript understands PDF (a PostScript derivative) to a much deeper level than ImageMagick does.