How to call pdfbox's API with JPype.

jpype_api_demo.py

#!/usr/bin/env python3

"""
How to call pdfbox's API with JPype.
"""

import pathlib
import pkg_resources
import re
import urllib.request

import appdirs
import jpype
import jpype.imports
import numpy as np

# Replace with path to pdfbox jar file:
a = appdirs.AppDirs('python-pdfbox')
cache_dir = pathlib.Path(a.user_cache_dir)
file_list = list(cache_dir.glob('pdfbox-app-*.jar'))
def f(s):
    v = re.search('pdfbox-app-([\w\.\-]+)\.jar', s.name).group(1)
    return pkg_resources.parse_version(v)
jpype.addClassPath(sorted(file_list, key=f)[-1])

if not jpype.isJVMStarted():
    jpype.startJVM(jpype.getDefaultJVMPath(), '-Djava.awt.headless=true', convertStrings=False)
from java.awt.image import BufferedImage
from java.io import File
from org.apache.pdfbox.pdmodel import PDDocument
from org.apache.pdfbox.rendering import ImageType, PDFRenderer

def extract_images(in_file, pages=None, dpi=72):
    """
    Extract pages of PDF file as images.

    Parameters
    ----------
    in_file : str
        Path to input PDF file.
    pages : iterable
        Numbers of pages to extract (0-indexed). If None, return all pages.
    dpi : int
        Resolution at which to render output images.

    Returns
    -------
    output : list of numpy.ndarray
        PDF pages rendered into RGB numpy arrays.
    """

    doc = PDDocument.load(File(in_file))
    pdf_renderer = PDFRenderer(doc)
    output = []
    if pages == None:
        pages = range(doc.getNumberOfPages())
    for i in pages:
        im = pdf_renderer.renderImageWithDPI(i, dpi)
        h = im.getHeight()
        w = im.getWidth()

        # Retrieve data as numpy array of RGB values packed into int32:
        data = im.getRGB(0, 0, w, h, None, 0, w)[:]

        # Separate RGB channels, return as array of bytes:
        output.append(np.frombuffer(memoryview(data), np.uint8).reshape(h, w, 4)[..., :3])
    return output

if __name__ == '__main__':
    import os
    import tempfile
    import urllib

    # Download sample multipage PDF:
    data = urllib.request.urlopen('https://researchtorevenue.files.wordpress.com/2015/04/1r41ai10801601_fong.pdf').read()
    fd, name = tempfile.mkstemp()
    f = open(name, 'wb')
    f.write(data)
    f.close()
    result = extract_images(name)
    os.unlink(name)

See also
lebedov/python-pdfbox#10
https://gist.github.com/mara004/51c3216a9eabd3dcbc78a86d877a61dc