2

我在 macbook 上使用 OpenCV 2.4 和 python 2.7.5。我想使用以下代码显示内置摄像头的实时流：

import cv

cv.NamedWindow("w1", cv.CV_WINDOW_AUTOSIZE)
camera_index = 0
capture = cv.CaptureFromCAM(camera_index)

def repeat():
    global capture #declare as globals since we are assigning to them now
    global camera_index
    frame = cv.QueryFrame(capture)
    print type(frame)
    #cv.ShowImage("w1", frame)
    c = cv.WaitKey(10)
while True:
    repeat()

但是，QueryFrame 似乎并不总是返回 iplimage，这是我在终端上得到的：

<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'cv2.cv.iplimage'>
<type 'NoneType'>
<type 'NoneType'>
<type 'cv2.cv.iplimage'>
<type 'NoneType'>
<type 'NoneType'>
<type 'NoneType'>
<type 'cv2.cv.iplimage'>
<type 'NoneType'>
<type 'NoneType'>
<type 'cv2.cv.iplimage'>
<type 'NoneType'>

有谁知道问题出在哪里？

谢谢

编辑：我注意到在我的相机打开之前需要几秒钟，所以我在进入“while”之前放了一些延迟。至于 noneType 问题，我不知道为什么我每 3 帧就会得到一个正确的图像。无论如何，我只是通过设置一个条件来检查我们是否得到正确的图像来“修复”它，这里是代码： 

import cv

cv.NamedWindow("w1", cv.CV_WINDOW_AUTOSIZE)
camera_index = 0
capture = cv.CaptureFromCAM(camera_index)
c = cv.WaitKey(5000)
def repeat():
    global capture #declare as globals since we are assigning to them now
    global camera_index
    frame = cv.QueryFrame(capture)

    if frame:

        cv.ShowImage("w1", frame)
    c = cv.WaitKey(10)
while True:
    repeat()
4

1 回答 1

1

建议如下：

  • camera_index = -1

  • 删除第一帧以防万一

    firstImage = copy.deepcopy(cv.QueryFrame(capture))

分享我的代码供您参考：

import cv2 as cv
import copy
camera_index = -1 

capture = cv.CaptureFromCAM(camera_index)

isRunning = True
firstImage = copy.deepcopy(cv.QueryFrame(capture)) #drop first frame which might empty
cv.NamedWindow("Webcam",  cv.CV_WINDOW_AUTOSIZE);

def repeat():
    global capture #declare as globals since we are assigning to them now
    global camera_index
    global isRunning
    global firstImage
    currImage = cv.QueryFrame(capture) 
    cv.ShowImage("Webcam",currImage)
    c = cv.WaitKey(10)
    if(c==27):
            isRunning = False
    if (c!=-1):
            print str(c)

while isRunning:
    repeat()
于 2014-04-27T05:11:51.023 回答