diff --git a/README.md b/README.md
index b28d3e3..9891c4d 100644
--- a/README.md
+++ b/README.md
@@ -1,15 +1,29 @@
-# photo-to-kml #
+# pdf-unlock #
 
-__photo-to-kml__ creates a kml file that shows geotagged images in Google Earth.
-
-![Images shwon in Google Earth](doc/google-earth.jpg)
+__pdf_unlock__ removes security features from pdfs.
 
 ## Installation ##
 
-`pip install simplekml`
+[Ghostscript](https://ghostscript.com) is required. When installing Ghostscript, make sure there is an executable called `gs` in your path. This should happen automatically with Linux, but Windows users will have to add the path to Ghostscript to the `PATH` environment variable manually, eg:
+
+`C:\Program Files\gs\gs9.21\bin`
+
+Then the Ghostscript executable `gswin64.exe` should be copied to a new executable called `gs.exe`.
 
 ## Usage ##
 
-Create a kml for a folder of photos, named 'image_folder':
 
-`python photo_to_kml.py image_folder`
+Search for pdfs inside 'pdf_folder', then create new unlocked versions
+of the pdfs with the the suffix '-unlocked.pdf':
+
+`> python pdf_unlock.py pdf_folder`
+
+Search for pdfs inside 'pdf_folder', then unlock the pdfs and overwrite
+the original versions.
+
+`> python pdf_unlock.py pdf_folder -o`
+
+Search recursively for pdfs inside 'pdf_folder' and all subfolders,
+then unlock the pdfs and overwrite the original versions.
+
+`> python pdf_unlock.py pdf_folder -o -r`
diff --git a/scripts/pdf_unlock.py b/scripts/pdf_unlock.py
index ac514f4..4d9d9e7 100644
--- a/scripts/pdf_unlock.py
+++ b/scripts/pdf_unlock.py
@@ -38,7 +38,6 @@ __version__ = "0.1.0"
 __email__ = "d.howe@wrl.unsw.edu.au"
 
 import os
-import sys
 import glob
 import argparse
 import subprocess