distrans.py sample added

samples/python2/distrans.py

@@ -0,0 +1,55 @@
+import numpy as np
+import cv2, cv
+from common import make_cmap
+
+help_message = '''USAGE: distrans.py [<image>]
+
+Keys:
+  ESC   - exit
+  v     - toggle voronoi mode
+'''
+
+if __name__ == '__main__':
+    import sys
+    try: fn = sys.argv[1]
+    except: fn = '../cpp/fruits.jpg'
+    print help_message
+
+    img = cv2.imread(fn, 0)
+    cm = make_cmap('jet')
+    need_update = True
+    voronoi = False
+
+    def update(dummy=None):
+        global need_update
+        need_update = False
+        thrs = cv2.getTrackbarPos('threshold', 'distrans')
+        mark = cv2.Canny(img, thrs, 3*thrs)
+        dist, labels = cv2.distanceTransform(~mark, cv.CV_DIST_L2, 5)
+        if voronoi:
+            vis = cm[np.uint8(labels)]
+        else:
+            vis = cm[np.uint8(dist*2)]
+        vis[mark != 0] = 255
+        cv2.imshow('distrans', vis)
+
+    def invalidate(dummy=None):
+        global need_update
+        need_update = True
+
+    cv2.namedWindow('distrans') 
+    cv2.createTrackbar('threshold', 'distrans', 60, 255, invalidate)
+    update()
+
+
+    while True:
+        ch = cv2.waitKey(50)
+        if ch == 27:
+            break
+        if ch == ord('v'):
+            voronoi = not voronoi
+            print 'showing', ['distance', 'voronoi'][voronoi]
+            update()
+        if need_update:
+            update()
+