diff --git a/python/README.md b/python/README.md
index 1c04702..6fada28 100644
--- a/python/README.md
+++ b/python/README.md
@@ -5,8 +5,7 @@ NanoVNA is able to be controlled via USB serial interface from PC. There are sam
 ## Preparation
 
     $ cd python
-    $ pip install numpy
-    $ pip install scikit-rf   
+    $ pip3 install -r requirements.txt
 
 ## Run
 
@@ -22,6 +21,10 @@ NanoVNA is able to be controlled via USB serial interface from PC. There are sam
 
     $ ./nanovna.py -s
 
+### Capture display
+
+    $ ./nanovna.py -C out.png
+
 ### Show usage.
 
     $ ./nanovna.py -h
diff --git a/python/requirements.txt b/python/requirements.txt
new file mode 100644
index 0000000..9e06290
--- /dev/null
+++ b/python/requirements.txt
@@ -0,0 +1,4 @@
+matplotlib
+scipy
+scikit-rf
+pillow