--- a/scripts/compute-homography.py	Tue Mar 24 14:17:12 2015 +0100
+++ b/scripts/compute-homography.py	Tue Mar 24 18:11:28 2015 +0100
@@ -75,10 +75,10 @@
 
 
 homography = np.array([])
-if args.pointCorrespondencesFilename != None:
+if args.pointCorrespondencesFilename is not None:
     worldPts, videoPts = cvutils.loadPointCorrespondences(args.pointCorrespondencesFilename)
     homography, mask = cv2.findHomography(videoPts, worldPts) # method=0, ransacReprojThreshold=3
-elif args.videoFrameFilename != None and args.worldFilename != None:
+elif args.videoFrameFilename is not None and args.worldFilename is not None:
     worldImg = plt.imread(args.worldFilename)
     videoImg = plt.imread(args.videoFrameFilename)
     if args.undistort:        
@@ -103,7 +103,7 @@
 if homography.size>0:
     np.savetxt('homography.txt',homography)
 
-if args.displayPoints and args.videoFrameFilename != None and args.worldFilename != None and homography.size>0:
+if args.displayPoints and args.videoFrameFilename is not None and args.worldFilename is not None and homography.size>0:
     worldImg = cv2.imread(args.worldFilename)
     videoImg = cv2.imread(args.videoFrameFilename)
     if args.undistort: