Fixed shebangs, added error checking

samples/python2/gabor_threads.py

@@ -1,4 +1,4 @@
-#/usr/bin/env python
+#!/usr/bin/env python
 
 '''
 gabor_threads.py
@@ -49,10 +49,16 @@ if __name__ == '__main__':
     from common import Timer
 
     print __doc__
-    try: img_fn = sys.argv[1]
-    except: img_fn = '../cpp/baboon.jpg'
+    try:
+        img_fn = sys.argv[1]
+    except: 
+        img_fn = '../cpp/baboon.jpg'
 
     img = cv2.imread(img_fn)
+    if img is None:
+        print 'Failed to load image file:', img_fn
+        sys.exit(1)
+    
     filters = build_filters()
 
     with Timer('running single-threaded'):