1#!/usr/bin/env python 2 3''' 4Texture flow direction estimation. 5 6Sample shows how cv2.cornerEigenValsAndVecs function can be used 7to estimate image texture flow direction. 8 9Usage: 10 texture_flow.py [<image>] 11''' 12 13import numpy as np 14import cv2 15 16if __name__ == '__main__': 17 import sys 18 try: 19 fn = sys.argv[1] 20 except: 21 fn = '../data/starry_night.jpg' 22 23 img = cv2.imread(fn) 24 if img is None: 25 print 'Failed to load image file:', fn 26 sys.exit(1) 27 28 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) 29 h, w = img.shape[:2] 30 31 eigen = cv2.cornerEigenValsAndVecs(gray, 15, 3) 32 eigen = eigen.reshape(h, w, 3, 2) # [[e1, e2], v1, v2] 33 flow = eigen[:,:,2] 34 35 vis = img.copy() 36 vis[:] = (192 + np.uint32(vis)) / 2 37 d = 12 38 points = np.dstack( np.mgrid[d/2:w:d, d/2:h:d] ).reshape(-1, 2) 39 for x, y in points: 40 vx, vy = np.int32(flow[y, x]*d) 41 cv2.line(vis, (x-vx, y-vy), (x+vx, y+vy), (0, 0, 0), 1, cv2.LINE_AA) 42 cv2.imshow('input', img) 43 cv2.imshow('flow', vis) 44 cv2.waitKey() 45
