Call pdftopng in subprocess

camelot/backends/ghostscript_backend.py

@@ -35,7 +35,7 @@ class GhostscriptBackend(object):
                 "here: https://camelot-py.readthedocs.io/en/master/user/install-deps.html"
             )
 
-        gs_args = [
+        gs_command = [
             "gs",
             "-q",
             "-sDEVICE=png16m",
@@ -44,4 +44,4 @@ class GhostscriptBackend(object):
             f"-r{resolution}",
             pdf_path,
         ]
-        ghostscript.Ghostscript(*gs_args)
+        ghostscript.Ghostscript(*gs_command)

camelot/backends/poppler_backend.py

@@ -1,8 +1,15 @@
 # -*- coding: utf-8 -*-
 
-from pdftopng import pdftopng
+import subprocess
 
 
 class PopplerBackend(object):
     def convert(self, pdf_path, png_path):
-        pdftopng.convert(pdf_path, png_path)
+        pdftopng_command = ["pdftopng", pdf_path, png_path]
+
+        try:
+            subprocess.check_output(
+                " ".join(pdftopng_command), stderr=subprocess.STDOUT, shell=True
+            )
+        except subprocess.CalledProcessError as e:
+            raise ValueError(e.output)