python-opencv 网络摄像头 [“noneType”]

Question

几周前，我尝试使用 python 和 opencv 移动鼠标指针...我没有时间这样做，今天我意外地发现了一段代码，我的问题是我无法再使用 opencv 打开我的网络摄像头...

我正在使用 ubuntu 10.04 ... /dev/video0 正在工作，我可以执行 luvcview -d /dev/video0

但是当我说camera = highgui.cvCreateCaptureCamera(0) 并尝试输入（camera）时，我得到 noneType ...

我已经 apt-get remove --清除 python-opencv 并重新安装它...但我无法使其工作...不知道出了什么问题几周前它工作了，现在...

这是使用 python opencv 和 Xlib 控制鼠标的代码.. 不知道

#! /usr/bin/env python

print "OpenCV Python version of lkdemo"

import sys
import os

sys.path.insert(1, os.path.join(sys.path[0], '..'))
from Xlib import X, display, Xutil
# import the necessary things for OpenCV
from opencv import cv
from opencv import highgui

#############################################################################
# some "constants"

win_size = 10
MAX_COUNT = 500

#############################################################################
# some "global" variables

image = None
pt = None
add_remove_pt = False
flags = 0
night_mode = False
need_to_init = False

#############################################################################
# the mouse callback

# the callback on the trackbar
class Window:
    def __init__(self, display):
        self.d = display
        self.objects = []

        # Find which screen to open the window on
        self.screen = self.d.screen()

        self.window = self.screen.root.create_window(
            50, 50, 300, 200, 2,
            self.screen.root_depth,
            X.InputOutput,
            X.CopyFromParent,

            # special attribute values
            background_pixel = self.screen.white_pixel,
            event_mask = (X.ExposureMask |
                          X.StructureNotifyMask |
                          X.ButtonPressMask |
                          X.ButtonReleaseMask |
                          X.Button1MotionMask),
            colormap = X.CopyFromParent,
            )

        self.gc = self.window.create_gc(
            foreground = self.screen.black_pixel,
            background = self.screen.white_pixel,
            )
    def mousekiller(self):
        self.gc = self.window.warp_pointer (the_point.x*6, the_point.y*6, src_window = 0, src_x = 0, src_y = 0, src_width = 0, src_height = 0, onerror = None )

        # Set some WM info

        self.WM_DELETE_WINDOW = self.d.intern_atom('WM_DELETE_WINDOW')
        self.WM_PROTOCOLS = self.d.intern_atom('WM_PROTOCOLS')

        self.window.set_wm_name('Xlib example: draw.py')
        self.window.set_wm_icon_name('draw.py')
        self.window.set_wm_class('draw', 'XlibExample')

        self.window.set_wm_protocols([self.WM_DELETE_WINDOW])
        self.window.set_wm_hints(flags = Xutil.StateHint,
                                 initial_state = Xutil.NormalState)

        self.window.set_wm_normal_hints(flags = (Xutil.PPosition | Xutil.PSize
                                                 | Xutil.PMinSize),
                                        min_width = 20,
                                        min_height = 20)

        # Map the window, making it visible
        self.window.map()

def on_mouse (event, x, y, flags, param):

    # we will use the global pt and add_remove_pt
    global pt
    global add_remove_pt

    if image is None:
        return

    if event == highgui.CV_EVENT_LBUTTONDOWN:
        # user has click, so memorize it
        pt = cv.cvPoint (x, y)
        add_remove_pt = True

#############################################################################
# so, here is the main part of the program

if __name__ == '__main__':
    Window(display.Display())
    capture = highgui.cvCreateCameraCapture(-1)           

    # check that capture device is OK
    if not capture:
        print "Error opening capture device"
        sys.exit (1)

    # display a small howto use it
    print "Hot keys: \n" \
          "\tESC - quit the program\n" \
          "\tr - auto-initialize tracking\n" \
          "\tc - delete all the points\n" \
          "\tn - switch the \"night\" mode on/off\n" \
          "To add/remove a feature point click it\n"

    # first, create the necessary windows

    highgui.cvNamedWindow ('LkDemo', highgui.CV_WINDOW_AUTOSIZE)

    # register the mouse callback
    highgui.cvSetMouseCallback ('LkDemo', on_mouse, None)

    while 1:
        # do forever

        # 1. capture the current image
        frame = highgui.cvQueryFrame (capture)
        if frame is None:
            # no image captured... end the processing
            break

        if image is None:
            # create the images we need
            image = cv.cvCreateImage (cv.cvGetSize (frame), 8, 3)
            image.origin = frame.origin
            grey = cv.cvCreateImage (cv.cvGetSize (frame), 8, 1)
            prev_grey = cv.cvCreateImage (cv.cvGetSize (frame), 8, 1)
            pyramid = cv.cvCreateImage (cv.cvGetSize (frame), 8, 1)
            prev_pyramid = cv.cvCreateImage (cv.cvGetSize (frame), 8, 1)
            points = [[], []]

        # copy the frame, so we can draw on it
        cv.cvCopy (frame, image)

        # create a grey version of the image
        cv.cvCvtColor (image, grey, cv.CV_BGR2GRAY)

        if night_mode:
            # night mode: only display the points
            cv.cvSetZero (image)

        if need_to_init:
            # we want to search all the good points

            # create the wanted images
            eig = cv.cvCreateImage (cv.cvGetSize (grey), 32, 1)
            temp = cv.cvCreateImage (cv.cvGetSize (grey), 32, 1)

            # the default parameters
            quality = 0.01
            min_distance = 10

            # search the good points
            points [1] = cv.cvGoodFeaturesToTrack (
                grey, eig, temp,
                MAX_COUNT,
                quality, min_distance, None, 3, 0, 0.04)

            # refine the corner locations
            cv.cvFindCornerSubPix (
                grey,
                points [1],
                cv.cvSize (win_size, win_size), cv.cvSize (-1, -1),
                cv.cvTermCriteria (cv.CV_TERMCRIT_ITER | cv.CV_TERMCRIT_EPS,
                                   20, 0.03))

            # release the temporary images
            cv.cvReleaseImage (eig)
            cv.cvReleaseImage (temp)

        elif len (points [0]) > 0:
            # we have points, so display them

            # calculate the optical flow
            points [1], status = cv.cvCalcOpticalFlowPyrLK (
                prev_grey, grey, prev_pyramid, pyramid,
                points [0], len (points [0]),
                cv.cvSize (win_size, win_size), 3,
                len (points [0]),
                None,
                cv.cvTermCriteria (cv.CV_TERMCRIT_ITER|cv.CV_TERMCRIT_EPS,
                                   20, 0.03),
                flags)

            # initializations
            point_counter = -1
            new_points = []

            for the_point in points [1]:
                # go trough all the points

                # increment the counter
                point_counter += 1

                if add_remove_pt:
                    # we have a point to add, so see if it is close to
                    # another one. If yes, don't use it
                    dx = pt.x - the_point.x
                    dy = pt.y - the_point.y
                    if dx * dx + dy * dy <= 25:
                        # too close
                        add_remove_pt = 0
                        continue

                if not status [point_counter]:
                    # we will disable this point
                    continue

                # this point is a correct point
                new_points.append (the_point)

                # draw the current point
                cv.cvCircle (image,
                             [the_point.x, the_point.y],
                             3, cv.cvScalar (0, 255, 0, 0),
                             -1, 8, 0)
                Window(display.Display()).mousekiller()

            # set back the points we keep
            points [1] = new_points

        if add_remove_pt:
            # we want to add a point
            points [1].append (cv.cvPointTo32f (pt))

            # refine the corner locations
            points [1][-1] = cv.cvFindCornerSubPix (
                grey,
                [points [1][-1]],
                cv.cvSize (win_size, win_size), cv.cvSize (-1, -1),
                cv.cvTermCriteria (cv.CV_TERMCRIT_ITER | cv.CV_TERMCRIT_EPS,
                                   20, 0.03))[0]

            # we are no more in "add_remove_pt" mode
            add_remove_pt = False

        # swapping
        prev_grey, grey = grey, prev_grey
        prev_pyramid, pyramid = pyramid, prev_pyramid
        points [0], points [1] = points [1], points [0]
        need_to_init = False

        # we can now display the image
        highgui.cvShowImage ('LkDemo', image)

        # handle events
        c = highgui.cvWaitKey (10)

        if c == '\x1b':
            # user has press the ESC key, so exit
            break

        # processing depending on the character
        if c in ['r', 'R']:
            need_to_init = True
        elif c in ['c', 'C']:
            points = [[], []]
        elif c in ['n', 'N']:
            night_mode = not night_mode

该怎么办了...希望有人遇到这个问题并解决... 提前谢谢。

Answer 1

如果我理解正确的话，你正在尝试让鼠标反馈发挥作用。

为此，您需要创建一个“响应程序”函数（下面文档中的“OnMouse”函数）。这是由 cv2.setMouseCallBack 函数使用的。

例如：

def mouseHandle(event, x, y, flag, param):
    if (flag == 1):
        print "hoosier at" + str(x) + " , " + str(y);

您还需要在代码中定义标志值，例如：

CV_EVENT_LBUTTONDOWN = 1;

现在在您的主函数中：

im = cv2.imread('myimage.jpg')
cv2.imshow('image', im)
cv2.setMouseCallback('image', mouseHandle, CV_EVENT_LBUTTONDOWN)

作为参考，以下是 opencv 文档中的函数信息：
http://opencv.willowgarage.com/documentation/python/highgui_user_interface.html

SetMouseCallback(windowName, onMouse, param) → 无
为鼠标事件分配回调。

参数：
windowName (str) – 窗口的名称。

onMouse (PyCallableObject) – 每次指定窗口中发生鼠标事件时可调用。该可调用函数应具有签名 Foo(event, x, y, flags, param)-> None 其中 event 是 CV_EVENT_* 之一，x 和 y 是鼠标指针在图像坐标（不是窗口坐标）中的坐标，flags 是 CV_EVENT_FLAG_* 的组合，param 是传递给的用户定义参数调用cvSetMouseCallback函数。

param (object) – 要传递给回调函数的用户定义参数。
函数 cvSetMouseCallback 设置指定窗口内发生的鼠标事件的回调函数。