Python，OpenCV:从WebCam捕获图像 [英] Python, OpenCV : Capture Images from WebCam

问题描述

我将Logitech C920挂接到我的PC上，并试图使用它通过OpenCV单击图片.

I have a Logitech C920 hooked to my PC and am trying to use it to click pictures using OpenCV.

我知道我可以使用:

cam = cv2.VideoCapture(1)
s, im = cam.read() # captures image
cv2.imshow("Test Picture", im) # displays captured image
cv2.imwrite("test.bmp",im) # writes image test.bmp to disk

但是它为我提供了我的相机能够拍摄的15MP静态照片.如果我click图片，我从上面得到的效果远远不如我期望的.

But it get me the 15MP still photography that my camera is capable of. What I get from above is far inferior to what I can expect if I click pictures.

那么，有什么方法可以拍照(就像可以在官方WebCam软件中完成)吗?

So, is there a way to take pictures (like it can be done in the official WebCam software) ?

推荐答案

使用此上一个问题作为指南进行测试后，我编写了以下程序来检查相机的设置(Logitech S7500 USB网络摄像头).我在Windows 7上使用Python 2.7和OpenCV 2.4.6.

After testing with this previous question as a guide, I wrote the following program to check my camera's settings (Logitech S7500 USB Webcam). I am using Python 2.7 and OpenCV 2.4.6 on Windows 7.

希望您可以使用此代码作为指导来修改相机上的设置，以获取所需的分辨率(或接近分辨率)(使用OpenCV的set()功能.)

Hopefully you can use this code as a guide to modify the setting on your camera to get the resolution (or close to it) you need (using the set() function from OpenCV.)

如果每个摄像机设置的值全部为0.0，则可能无法调整摄像机设置.在笔记本电脑的内置网络摄像头上运行该程序时，我遇到了这种情况.

If you get all 0.0 as the values for each camera setting, then you may not have the ability to adjust the camera settings. I experienced this when running this program on my laptop's built-in webcam.

from __future__ import print_function
import sys
import cv2


def main(argv):
    #capture from camera at location 0
    cap = cv2.VideoCapture(0)
    # Change the camera setting using the set() function
    # cap.set(cv2.cv.CV_CAP_PROP_EXPOSURE, -6.0)
    # cap.set(cv2.cv.CV_CAP_PROP_GAIN, 4.0)
    # cap.set(cv2.cv.CV_CAP_PROP_BRIGHTNESS, 144.0)
    # cap.set(cv2.cv.CV_CAP_PROP_CONTRAST, 27.0)
    # cap.set(cv2.cv.CV_CAP_PROP_HUE, 13.0) # 13.0
    # cap.set(cv2.cv.CV_CAP_PROP_SATURATION, 28.0)
    # Read the current setting from the camera
    test = cap.get(cv2.cv.CV_CAP_PROP_POS_MSEC)
    ratio = cap.get(cv2.cv.CV_CAP_PROP_POS_AVI_RATIO)
    frame_rate = cap.get(cv2.cv.CV_CAP_PROP_FPS)
    width = cap.get(cv2.cv.CV_CAP_PROP_FRAME_WIDTH)
    height = cap.get(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT)
    brightness = cap.get(cv2.cv.CV_CAP_PROP_BRIGHTNESS)
    contrast = cap.get(cv2.cv.CV_CAP_PROP_CONTRAST)
    saturation = cap.get(cv2.cv.CV_CAP_PROP_SATURATION)
    hue = cap.get(cv2.cv.CV_CAP_PROP_HUE)
    gain = cap.get(cv2.cv.CV_CAP_PROP_GAIN)
    exposure = cap.get(cv2.cv.CV_CAP_PROP_EXPOSURE)
    print("Test: ", test)
    print("Ratio: ", ratio)
    print("Frame Rate: ", frame_rate)
    print("Height: ", height)
    print("Width: ", width)
    print("Brightness: ", brightness)
    print("Contrast: ", contrast)
    print("Saturation: ", saturation)
    print("Hue: ", hue)
    print("Gain: ", gain)
    print("Exposure: ", exposure)
    while True:
        ret, img = cap.read()
        cv2.imshow("input", img)

        key = cv2.waitKey(10)
        if key == 27:
            break

    cv2.destroyAllWindows()
    cv2.VideoCapture(0).release()


#   0  CV_CAP_PROP_POS_MSEC Current position of the video file in milliseconds.
#   1  CV_CAP_PROP_POS_FRAMES 0-based index of the frame to be decoded/captured next.
#   2  CV_CAP_PROP_POS_AVI_RATIO Relative position of the video file
#   3  CV_CAP_PROP_FRAME_WIDTH Width of the frames in the video stream.
#   4  CV_CAP_PROP_FRAME_HEIGHT Height of the frames in the video stream.
#   5  CV_CAP_PROP_FPS Frame rate.
#   6  CV_CAP_PROP_FOURCC 4-character code of codec.
#   7  CV_CAP_PROP_FRAME_COUNT Number of frames in the video file.
#   8  CV_CAP_PROP_FORMAT Format of the Mat objects returned by retrieve() .
#   9 CV_CAP_PROP_MODE Backend-specific value indicating the current capture mode.
#   10 CV_CAP_PROP_BRIGHTNESS Brightness of the image (only for cameras).
#   11 CV_CAP_PROP_CONTRAST Contrast of the image (only for cameras).
#   12 CV_CAP_PROP_SATURATION Saturation of the image (only for cameras).
#   13 CV_CAP_PROP_HUE Hue of the image (only for cameras).
#   14 CV_CAP_PROP_GAIN Gain of the image (only for cameras).
#   15 CV_CAP_PROP_EXPOSURE Exposure (only for cameras).
#   16 CV_CAP_PROP_CONVERT_RGB Boolean flags indicating whether images should be converted to RGB.
#   17 CV_CAP_PROP_WHITE_BALANCE Currently unsupported
#   18 CV_CAP_PROP_RECTIFICATION Rectification flag for stereo cameras (note: only supported by DC1394 v 2.x backend currently)

if __name__ == '__main__':
    main(sys.argv)

此处是有关此主题的OpenCV问题和 OpenCV文档

Here is a link to an OpenCV question about this topic and the OpenCV Documentation

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