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import matplotlib.pyplot as plt
import numpy as np
import scipy.signal as si
from PIL import Image
import deriv
import numpy.linalg as lin
def lk(im1, im2, window_size) :
u = np.zeros(im1.shape)
v = np.zeros(im2.shape)
fx, fy, ft = deriv.deriv(im1, im2)
halfWindow = np.floor(window_size/2)
for i in range(int(halfWindow+1),int(fx.shape[0]-halfWindow)):
for j in range(int(halfWindow+1),int(fx.shape[1]-halfWindow)):
curFx = fx[i-halfWindow-1:i+halfWindow,
j-halfWindow-1:j+halfWindow]
curFy = fy[i-halfWindow-1:i+halfWindow,
j-halfWindow-1:j+halfWindow]
curFt = ft[i-halfWindow-1:i+halfWindow,
j-halfWindow-1:j+halfWindow]
curFx = curFx.flatten()
curFy = curFy.flatten()
curFt = -curFt.flatten()
A = np.vstack((curFx, curFy)).T
U = np.dot(np.dot(lin.pinv(np.dot(A.T,A)),A.T),curFt)
u[i,j] = U[0]
v[i,j] = U[1]
return (u,v)
def lk_point(im1, im2, i, j, window_size) :
fx, fy, ft = deriv.deriv(im1, im2)
halfWindow = np.floor(window_size/2)
curFx = fx[i-halfWindow-1:i+halfWindow,
j-halfWindow-1:j+halfWindow]
curFy = fy[i-halfWindow-1:i+halfWindow,
j-halfWindow-1:j+halfWindow]
curFt = ft[i-halfWindow-1:i+halfWindow,
j-halfWindow-1:j+halfWindow]
#curFx = curFx.T
#curFy = curFy.T
#curFt = curFt.T
curFx = curFx.flatten()
curFy = curFy.flatten()
curFt = -curFt.flatten()
A = np.vstack((curFx, curFy)).T
U = np.dot(np.dot(lin.pinv(np.dot(A.T,A)),A.T),curFt)
return U[0], U[1]
if __name__ == "__main__":
x=165
y=95
win=50
im1 = np.asarray(Image.open('flow1-bw-0.png'))
print im1.shape
#im2 = np.asarray(Image.open('flow2-bw-0.png'))
#im2 = np.asarray(Image.open('upright.png'))
im2 = np.asarray(Image.open('dleft.png'))
print im2.shape
u, v = lk(im1, im2, x, y, win)
print u, v
plt.imshow(im1, cmap='gray')
plt.hold(True)
plt.plot(x,y,'+r');
plt.plot(x+u*3,y+v*3,'og')
plt.show()
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