如何在python opencv中保存光流输出？

我正在为我的实验室做一个项目，用光流来计算物体的数量。有人能告诉我如何将光流输出视频写入存储在计算机上的新视频吗？谢谢大家!

import numpy as np
import cv2

cap = cv2.VideoCapture('crab2.mp4')

# params for ShiTomasi corner detection
feature_params = dict( maxCorners = 100,
                       qualityLevel = 0.3,
                        minDistance = 7,
                        blockSize = 7 )
# Parameters for lucas kanade optical flow
lk_params = dict( winSize  = (15,15),
                   maxLevel = 2,
                   criteria = (cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 10, 0.03)) 
 # Create some random colors
color = np.random.randint(0,255,(100,3))
# Take first frame and find corners in it
ret, old_frame = cap.read()
old_gray = cv2.cvtColor(old_frame, cv2.COLOR_BGR2GRAY)
p0 = cv2.goodFeaturesToTrack(old_gray, mask = None, **feature_params)

# Create a mask image for drawing purposes
mask = np.zeros_like(old_frame)

while(1):
     ret,frame = cap.read()
     frame_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) 
    # calculate optical flow
     p1, st, err = cv2.calcOpticalFlowPyrLK(old_gray, frame_gray, p0, None, **lk_params)

     # Select good points
     good_new = p1[st==1]
     good_old = p0[st==1]

     # draw the tracks
     for i,(new,old) in enumerate(zip(good_new,good_old)):
         a,b = new.ravel()
         c,d = old.ravel()
         mask = cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2)
         frame = cv2.circle(frame,(a,b),5,color[i].tolist(),-1)
     img = cv2.add(frame,mask)

     cv2.imshow('frame',img)
     k = cv2.waitKey(30) & 0xff
     if k == 27:
         break

     # Now update the previous frame and previous points
     old_gray = frame_gray.copy()
     p0 = good_new.reshape(-1,1,2)


cv2.destroyAllWindows()
cap.release()

---

这将起作用：

import numpy as np
import cv2

cap = cv2.VideoCapture('crab2.mp4')
output_file = "./crab2_track.mp4"
fourcc = cv2.VideoWriter_fourcc(*'DIVX')

# params for ShiTomasi corner detection
feature_params = dict( maxCorners = 100,
                       qualityLevel = 0.3,
                        minDistance = 7,
                        blockSize = 7 )
# Parameters for lucas kanade optical flow
lk_params = dict( winSize  = (15,15),
                   maxLevel = 2,
                   criteria = (cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 10, 0.03)) 
 # Create some random colors
color = np.random.randint(0,255,(100,3))
# Take first frame and find corners in it
ret, old_frame = cap.read()
old_gray = cv2.cvtColor(old_frame, cv2.COLOR_BGR2GRAY)
p0 = cv2.goodFeaturesToTrack(old_gray, mask = None, **feature_params)

# Create a mask image for drawing purposes
mask = np.zeros_like(old_frame)
is_begin = True

while(1):
     ret,frame = cap.read()
     if frame is None:
         break
     processed = frame

     if is_begin:
         h, w, _ = processed.shape
         out = cv2.VideoWriter(output_file, fourcc, 30, (w, h), True)
         is_begin = False

     frame_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) 
    # calculate optical flow
     p1, st, err = cv2.calcOpticalFlowPyrLK(old_gray, frame_gray, p0, None, **lk_params)

     # Select good points
     good_new = p1[st==1]
     good_old = p0[st==1]

     # draw the tracks
     for i,(new,old) in enumerate(zip(good_new,good_old)):
         a,b = new.ravel()
         c,d = old.ravel()
         mask = cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2)
         frame = cv2.circle(frame,(a,b),5,color[i].tolist(),-1)
     img = cv2.add(frame,mask)

     out.write(img)
     cv2.imshow('frame',img)
     k = cv2.waitKey(30) & 0xff
     if k == 27:
         break

     # Now update the previous frame and previous points
     old_gray = frame_gray.copy()
     p0 = good_new.reshape(-1,1,2)


cv2.destroyAllWindows()
cap.release()

---

它将用跟踪行保存文件。

您尝试过cv2.VideoWriter对象吗？这对你来说失败了吗？