distrans.py sample added

samples/python2/common.py

@@ -83,3 +83,29 @@ class Sketcher:
             self.show()
         else:
             self.prev_pt = None
+
+
+# palette data from matplotlib/_cm.py
+_jet_data =   {'red':   ((0., 0, 0), (0.35, 0, 0), (0.66, 1, 1), (0.89,1, 1),
+                         (1, 0.5, 0.5)),
+               'green': ((0., 0, 0), (0.125,0, 0), (0.375,1, 1), (0.64,1, 1),
+                         (0.91,0,0), (1, 0, 0)),
+               'blue':  ((0., 0.5, 0.5), (0.11, 1, 1), (0.34, 1, 1), (0.65,0, 0),
+                         (1, 0, 0))}
+
+cmap_data = { 'jet' : _jet_data }
+
+def make_cmap(name, n=256):
+    data = cmap_data[name]
+    xs = np.linspace(0.0, 1.0, n)
+    channels = []
+    eps = 1e-6
+    for ch_name in ['blue', 'green', 'red']:
+        ch_data = data[ch_name]
+        xp, yp = [], []
+        for x, y1, y2 in ch_data:
+            xp += [x, x+eps]
+            yp += [y1, y2]
+        ch = np.interp(xs, xp, yp)
+        channels.append(ch)
+    return np.uint8(np.array(channels).T*255)

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()
+      

samples/python2/edge.py

@@ -18,7 +18,7 @@ while True:
     gray = cv2.cvtColor(img, cv.CV_BGR2GRAY)
     thrs1 = cv2.getTrackbarPos('thrs1', 'edge')
     thrs2 = cv2.getTrackbarPos('thrs2', 'edge')
-    edge = cv2.canny(gray, thrs1, thrs2, apertureSize=5)
+    edge = cv2.Canny(gray, thrs1, thrs2, apertureSize=5)
     vis = img.copy()
     vis /= 2
     vis[edge != 0] = (0, 255, 0)