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#/usr/bin/env python
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'''
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Coherence-enhancing filtering example
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=====================================
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inspired by
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Joachim Weickert "Coherence-Enhancing Shock Filters"
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http://www.mia.uni-saarland.de/Publications/weickert-dagm03.pdf
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'''
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import numpy as np
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import cv2
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def coherence_filter(img, sigma = 11, str_sigma = 11, blend = 0.5, iter_n = 4):
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h, w = img.shape[:2]
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for i in xrange(iter_n):
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print i,
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gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
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eigen = cv2.cornerEigenValsAndVecs(gray, str_sigma, 3)
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eigen = eigen.reshape(h, w, 3, 2) # [[e1, e2], v1, v2]
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x, y = eigen[:,:,1,0], eigen[:,:,1,1]
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gxx = cv2.Sobel(gray, cv2.CV_32F, 2, 0, ksize=sigma)
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gxy = cv2.Sobel(gray, cv2.CV_32F, 1, 1, ksize=sigma)
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gyy = cv2.Sobel(gray, cv2.CV_32F, 0, 2, ksize=sigma)
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gvv = x*x*gxx + 2*x*y*gxy + y*y*gyy
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m = gvv < 0
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ero = cv2.erode(img, None)
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dil = cv2.dilate(img, None)
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img1 = ero
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img1[m] = dil[m]
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img = np.uint8(img*(1.0 - blend) + img1*blend)
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print 'done'
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return img
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if __name__ == '__main__':
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import sys
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try: fn = sys.argv[1]
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except: fn = '../cpp/baboon.jpg'
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src = cv2.imread(fn)
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def nothing(*argv):
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pass
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def update():
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sigma = cv2.getTrackbarPos('sigma', 'control')*2+1
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str_sigma = cv2.getTrackbarPos('str_sigma', 'control')*2+1
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blend = cv2.getTrackbarPos('blend', 'control') / 10.0
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print 'sigma: %d str_sigma: %d blend_coef: %f' % (sigma, str_sigma, blend)
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dst = coherence_filter(src, sigma=sigma, str_sigma = str_sigma, blend = blend)
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cv2.imshow('dst', dst)
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cv2.namedWindow('control', 0)
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cv2.createTrackbar('sigma', 'control', 9, 15, nothing)
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cv2.createTrackbar('blend', 'control', 7, 10, nothing)
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cv2.createTrackbar('str_sigma', 'control', 9, 15, nothing)
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print 'Press SPACE to update the image\n'
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cv2.imshow('src', src)
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update()
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while True:
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ch = 0xFF & cv2.waitKey()
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if ch == ord(' '):
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update()
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if ch == 27:
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break
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cv2.destroyAllWindows()
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