• Add size=None parameter which uses either -scale-to, -scale-to-x or -scale-to-y in pdftoppm or pdftocairo
  • size=400 fits the image to a 400x400 pixels box, preserving aspect ratio
  • size=(400, None) makes the image 400 pixels wide, preserving aspect ratio
  • size=(None, 400) makes the image 400 pixels high, preserving aspect ratio
  • size=(400, 400) makes the image 400 pixels by 400 pixels, not preserving aspect ratio