python cv2 sample: hi-res image browse

samples/python2/browse.py

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+'''
+browse.py shows how to implement a simple hi resolution image navigation
+'''
+
+import numpy as np
+import cv2, cv
+import sys
+
+print 'This sample shows how to implement a simple hi resolution image navigation.'
+print 'USAGE: browse.py [image filename]'
+print 
+
+if len(sys.argv) > 1:
+    fn = sys.argv[1]
+    print 'loading %s ...' % fn
+    img = cv2.imread(fn)
+else:
+    sz = 4096
+    print 'generating %dx%d precudural image ...' % (sz, sz)
+    img = np.zeros((sz, sz), np.uint8)
+    track = np.cumsum(np.random.rand(1000000, 2)-0.5, axis=0)
+    track = np.int32(track*20 + (sz/2, sz/2))
+    cv2.polylines(img, [track], 0, 255, 1, cv.CV_AA)
+
+small = img
+for i in xrange(4):
+    small = cv2.pyrDown(small)
+
+def onmouse(event, x, y, flags, param):
+    h, w = img.shape[:2]
+    h1, w1 = small.shape[:2]
+    x, y = 1.0*x*h/h1, 1.0*y*h/h1
+    zoom = cv2.getRectSubPix(img, (800, 600), (x+0.5, y+0.5))
+    cv2.imshow('zoom', zoom)
+
+cv2.imshow('small', small)
+cv.SetMouseCallback('small', onmouse, None)
+cv2.waitKey()