1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
#!/usr/bin/env python
'''
example to show optical flow
USAGE: opt_flow.py [<video_source>]
Keys:
1 - toggle HSV flow visualization
2 - toggle glitch
Keys:
ESC - exit
'''
# Python 2/3 compatibility
from __future__ import print_function
import numpy as np
import cv2 as cv
import video
def draw_flow(img, flow, step=16):
h, w = img.shape[:2]
y, x = np.mgrid[step/2:h:step, step/2:w:step].reshape(2,-1).astype(int)
fx, fy = flow[y,x].T
lines = np.vstack([x, y, x+fx, y+fy]).T.reshape(-1, 2, 2)
lines = np.int32(lines + 0.5)
vis = cv.cvtColor(img, cv.COLOR_GRAY2BGR)
cv.polylines(vis, lines, 0, (0, 255, 0))
for (x1, y1), (_x2, _y2) in lines:
cv.circle(vis, (x1, y1), 1, (0, 255, 0), -1)
return vis
def draw_hsv(flow):
h, w = flow.shape[:2]
fx, fy = flow[:,:,0], flow[:,:,1]
ang = np.arctan2(fy, fx) + np.pi
v = np.sqrt(fx*fx+fy*fy)
hsv = np.zeros((h, w, 3), np.uint8)
hsv[...,0] = ang*(180/np.pi/2)
hsv[...,1] = 255
hsv[...,2] = np.minimum(v*4, 255)
bgr = cv.cvtColor(hsv, cv.COLOR_HSV2BGR)
return bgr
def warp_flow(img, flow):
h, w = flow.shape[:2]
flow = -flow
flow[:,:,0] += np.arange(w)
flow[:,:,1] += np.arange(h)[:,np.newaxis]
res = cv.remap(img, flow, None, cv.INTER_LINEAR)
return res
def main():
import sys
try:
fn = sys.argv[1]
except IndexError:
fn = 0
cam = video.create_capture(fn)
_ret, prev = cam.read()
prevgray = cv.cvtColor(prev, cv.COLOR_BGR2GRAY)
show_hsv = False
show_glitch = False
cur_glitch = prev.copy()
while True:
_ret, img = cam.read()
gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
flow = cv.calcOpticalFlowFarneback(prevgray, gray, None, 0.5, 3, 15, 3, 5, 1.2, 0)
prevgray = gray
cv.imshow('flow', draw_flow(gray, flow))
if show_hsv:
cv.imshow('flow HSV', draw_hsv(flow))
if show_glitch:
cur_glitch = warp_flow(cur_glitch, flow)
cv.imshow('glitch', cur_glitch)
ch = cv.waitKey(5)
if ch == 27:
break
if ch == ord('1'):
show_hsv = not show_hsv
print('HSV flow visualization is', ['off', 'on'][show_hsv])
if ch == ord('2'):
show_glitch = not show_glitch
if show_glitch:
cur_glitch = img.copy()
print('glitch is', ['off', 'on'][show_glitch])
print('Done')
if __name__ == '__main__':
print(__doc__)
main()
cv.destroyAllWindows()
|
