OpenCV灰度转换错误

Question

我正在尝试在OpenCV中打开一个视频源文件进行处理。我正在按照这里的教程进行操作：http://docs.opencv.org/trunk/doc/py_tutorials/py_video/py_lucas_kanade/py_lucas_kanade.html#lucas-kanade

每次我尝试打开一个.avi格式的视频文件进行处理时，都会收到以下错误：

    Traceback (most recent call last):
  File "C:\Users\Adam\Desktop\LastProjectAI\sources\samples\python2\lines.py", line 22, in <module>
    old_gray = cv2.cvtColor(old_frame, cv2.COLOR_BGR2GRAY)
error: ..\..\..\src\opencv\modules\imgproc\src\color.cpp:3402: error: (-215) scn == 3 || scn == 4

我从其他帖子中了解到，当源视频文件的通道数不是3或4时，会出现这样的错误。不过，我使用的是OpenCV教程提供的视频，所以我不明白为什么它们会无法工作。

这是我正在使用的完整代码：

import numpy as np
import cv2

cap = cv2.VideoCapture('walking.avi')

# 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()

需要注意以下几点：

我在Windows 8上使用Python编辑器IDLE。
我尝试加载的视频文件和Python文件在同一个文件夹里。

我尝试了多个视频文件，但都没有成功。有没有人能给我一些建议，帮我解决这个错误？

编辑：

我可以在从视频捕获对象读取帧后直接显示它。但是，如果我尝试在绘制轨迹的for循环之后加载帧，就会出现这个错误：

OpenCV Error: Bad flag (parameter or structure field) (Unrecognized or unsupported array type) in cvGetMat, file /build/buildd/opencv-2.4.5+dfsg/modules/core/src/array.cpp, line 2482
Traceback (most recent call last):
  File "prac.py", line 55, in <module>
    cv2.imshow('frame2', frame)
cv2.error: /build/buildd/opencv-2.4.5+dfsg/modules/core/src/array.cpp:2482: error: (-206) Unrecognized or unsupported array type in function cvGetMat

错误调试视频文件格式 opencv 视频处理灰度转换帧读取轨迹绘制通道数

OpenCV灰度转换错误

1 个回答

撰写回答