watershed.py sample added

samples/python2/watershed.py

+import numpy as np
+import cv2, cv
+
+help_message = '''
+  USAGE: watershed.py [<image>]
+
+  Use keys 1 - 7 to switch marker color
+  SPACE - update segmentation
+  r     - reset
+  a     - switch autoupdate
+  ESC   - exit
+
+'''
+
+class App:
+    def __init__(self, fn):
+        self.img = cv2.imread(fn)
+        h, w = self.img.shape[:2]
+        self.markers = np.zeros((h, w), np.int32)
+        self.markers_vis = self.img.copy()
+        self.cur_marker = 1
+        self.colors = np.int32( list(np.ndindex(2, 2, 2)) ) * 255
+
+        cv2.imshow('img', self.markers_vis)
+
+        self.prev_pt = None
+        self.need_update = False
+        self.auto_update = True
+        cv2.setMouseCallback('img', self.onmouse)
+
+
+    def onmouse(self, event, x, y, flags, param):
+        pt = (x, y)
+        if event == cv.CV_EVENT_LBUTTONDOWN:
+            self.prev_pt = pt
+        if self.prev_pt and flags & cv.CV_EVENT_FLAG_LBUTTON:
+            color = map(int, self.colors[self.cur_marker])
+            cv.Line(self.markers, self.prev_pt, pt, self.cur_marker, 5)
+            cv.Line(self.markers_vis, self.prev_pt, pt, color, 5)
+            self.need_update = True
+            self.prev_pt = pt
+            cv2.imshow('img', self.markers_vis)
+        else:
+            self.prev_pt = None
+
+    def watershed(self):
+        m = self.markers.copy()
+        cv2.watershed(self.img, m)
+        vis = np.uint8( (self.img + self.colors[np.maximum(m, 0)]) / 2 )
+        cv2.imshow('watershed', vis)
+        self.need_update = False
+
+    def run(self):
+        while True:
+            ch = cv2.waitKey(10)
+            if ch == 27:
+                break
+            if ch >= ord('1') and ch <= ord('7'):
+                self.cur_marker = ch - ord('0')
+                print 'marker: ', self.cur_marker
+            if ch == ord(' ') or (self.need_update and self.auto_update):
+                self.watershed()
+            if ch in [ord('a'), ord('A')]:
+                self.auto_update = not self.auto_update
+                print 'auto_update if', ['off', 'on'][self.auto_update]
+            if ch in [ord('r'), ord('R')]:
+                self.markers = np.zeros(self.img.shape[:2], np.int32)
+                self.markers_vis = self.img.copy()
+                cv2.imshow('img', self.markers_vis)
+                cv2.destroyWindow('watershed')
+
+
+if __name__ == '__main__':
+    import sys
+    try: fn = sys.argv[1]
+    except: fn = '../cpp/fruits.jpg'
+    print help_message
+    App(fn).run()