try to run convert, but fall back on gs if needed

src/paperless_tesseract/parsers.py

@@ -46,11 +46,25 @@ class RasterisedDocumentParser(DocumentParser):
         """
 
         out_path = os.path.join(self.tempdir, "convert.png")
-        gs_out_path = os.path.join(self.tempdir, "gs_out.png")
 
-        # Extract the first PDF page as a PNG using Ghostscript  
-        # https://github.com/danielquinn/paperless/issues/447
-        # call gs first
+        # Run convert to get a decent thumbnail
+        try:
+            run_convert(
+                self.CONVERT,
+                "-scale", "500x5000",
+                "-alpha", "remove",
+                "{}[0]".format(self.document_path),
+                out_path
+            )
+        except ParseError:
+            # if convert fails, fall back to extracting
+            # the first PDF page as a PNG using Ghostscript
+            self.log(
+                "warning",
+                "Thumbnail generation with ImageMagick failed, "
+                "falling back to Ghostscript."
+            )
+            gs_out_path = os.path.join(self.tempdir, "gs_out.png")
             cmd = [self.GHOSTSCRIPT,
                    "-q",
                    "-sDEVICE=pngalpha",