diff --git a/pykick/imagereaders.py b/pykick/imagereaders.py
index 25e26d5..89ee4cf 100644
--- a/pykick/imagereaders.py
+++ b/pykick/imagereaders.py
@@ -9,16 +9,40 @@ except:
 
 
 class NaoImageReader(object):
+    """Class for reading images from NAO.
+
+    Depends on ALProxy from NAOqi SDK.
+
+    """
 
     RESOLUTIONS = {
-        0: (120, 160),
-        1: (240, 320),
+        0: (120, 160),  # 160x120
+        1: (240, 320),  # and so on
         2: (480, 640),
         3: (960, 1280)
     }
 
-    def __init__(self, ip, port=9559, res=1, fps=30, cam_id=0, video_file=None):
-        ip = bytes(ip)
+    def __init__(self, ip, port=9559, res=1, fps=30, cam_id=0,
+                 video_file=None):
+        """
+        Parameters
+        ----------
+        ip : string
+            IP-Address of the NAO,
+        port : int
+            Port on NAO where ALProxy listens.
+        res : int
+            Resolution, see RESOLUTIONS above
+        fps : int
+            Frames per second, not sure if it does anything.
+        cam_id : 0 or 1
+            0 for top camera, 1 for lower camera.
+        video_file : string or None
+            Use None, otherwise is likely to crash.
+
+        """
+
+        ip = bytes(ip)  # Python2 thing
         self.res_id = res
         self.recording = []
         self.res = self.RESOLUTIONS[res]
@@ -32,15 +56,43 @@ class NaoImageReader(object):
         )
 
     def to_angles(self, x, y):
+        """Transform relative x, y coordinates into camera angles.
+
+        Parameters
+        ----------
+        x, y : float
+            Relative X and Y coordinate (0.0 to 1.0) as returned by
+            `to_relative`.
+
+        Returns
+        -------
+        tuple
+            (x_ang, y_ang) angular coordinates in camera frame in radians.
+
+        """
         return self.vd.getAngularPositionFromImagePosition(
             self.cam_id, [x, y]
         )
 
     def to_relative(self, x, y):
+        """Transform pixel coordinates into relative coordinates.
+
+        Parameters
+        ----------
+        x, y : float
+            Pixel coordinates to transform.
+
+        Returns
+        -------
+        tuple
+            (x_rel, y_rel) Relative (0.0 to 1.0) coordinates.
+
+        """
         print('Camera resolution:', self.res)
         return x / self.res[1], y / self.res[0]
 
     def get_frame(self):
+        """Get the next frame as a BGR OpenCV image."""
         result = self.vd.getImageRemote(self.sub)
         self.vd.releaseImage(self.sub)
         if result is None or result[6] is None:
@@ -56,6 +108,7 @@ class NaoImageReader(object):
             return frame
 
     def close(self):
+        """Stop and clean up."""
         self.vd.unsubscribe(self.sub)
         print(self.sub + 'captured %s frames' % len(self.recording))
         print('Writing to', self.video_file)
@@ -69,6 +122,7 @@ class NaoImageReader(object):
             vf.release()
 
     def restart(self):
+        """Restart the proxy if something went wrong."""
         self.vd.unsubscribe(self.sub)
         self.sub = self.vd.subscribeCamera(
             self.sub, self.cam_id, self.res_id, 13, self.fps
@@ -77,13 +131,25 @@ class NaoImageReader(object):
 
 
 class VideoReader(object):
+    """Class with the same interface as `NaoImageReader` for videofiles."""
 
     def __init__(self, filename=0, loop=False):
+        """
+        Parameters
+        ----------
+        filename : string or 0
+            Will try to read from file if name given or from webcam if 0
+            specified.
+        loop : bool
+            If video is over, start again or stop?
+
+        """
         self.cap = cv2.VideoCapture(filename)
         self.loop = loop if filename else False
         self.ctr = 0
 
     def get_frame(self):
+        """Get the next frame as a BGR OpenCV image."""
         succ, frame = self.cap.read()
         if not succ:
             raise ValueError('Error while reading video.\n' +
@@ -96,11 +162,12 @@ class VideoReader(object):
         return frame
 
     def close(self):
+        """Cleanup and stop."""
         self.cap.release()
 
 
 class PictureReader(object):
-    "Dummy class for maybe convenience."
+    "Dummy class for reading image files for maybe convenience."
 
     def __init__(self, filename):
         self.frame = cv2.imread(filename)
@@ -109,4 +176,4 @@ class PictureReader(object):
         return self.frame.copy()
 
     def close(self):
-        pass
+        self.frame = None