PDF scripts

Optimize PDFs

PDF "optimizations" (for example: stripping unnecessary data, rendering images in lower quality, when better quality is not needed, etc.) can be done with ghostscript. Here is the command you can use:

gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.3 -dPDFSETTINGS=/screen -sOutputFile=out.pdf in.pdf

Arguments:

• -q. Run in quiet mode. Without this flag, ghostscript executable will produce a lot of completely useless information. However, this flag can be used for debugging.
• -dNOPAUSE. By default, ghostscript will prompt you before processing each page. Useful when dealing with large files containing a lot of pages.
• dBATCH. Quit ghostscript after processing last file. Running ghostscript without this flag will make it open interactive "console" after processing.
• -sDEVICE=pdfwrite. Specify PDF device.
• -dCompatibilityLevel=1.3. Specify PDF compatibility level. If you are having issues with 1.3, you can try other variants such as 1.5, 1.4, 1.2 or 1.1.
• -dPDFSETTINGS=/screen. Specify "optimization" level. Here are supported values (source):

  Value	Description
  screen	Screen-view-only quality, 72 dpi images
  ebook	Low quality, 150 dpi images
  printer	High quality, 300 dpi images
  prepress	High quality, color preserving, 300 dpi images
  default	Almost identical to /screen

• -sOutputFile=out.pdf. Specify path to the output file. Since ghostscript executable actually accepts multiple input files, you must provide this argument before specifying input files.
• in.pdf. Input file.

Extracing pages

Page extraction can be implemented with Python3:

• Dependencies:

  pip install 'PyPDF2>=3.0.0'
  

• The script (only function):

  from typing import Iterable
  from PyPDF2 import PdfReader, PdfWriter
  
  
  def extract_pages(src: str, dest: str, pages: Iterable[int]) -> None:
      """Exract pages from `src` file and write them to `dest` file.
  
      :param src: Path to the input file.
      :param dest: Path to the output file.
      :param pages: Numbers (not indices!) of pages to extract.
          The first page (with index 0) has number 1.
      """
      reader, writer = PdfReader(src), PdfWriter()
  
      for number in pages:
          writer.add_page(reader.pages[number - 1])
  
      with open(dest, "wb") as file:
          writer.write(file)