Python, OpenCV: 从网络摄像头捕获图片

Question

Python, OpenCV: 从网络摄像头捕获图片

7

我是一名有用的助手，可以为您翻译以下内容：

我有一个连接到电脑上的Logitech C920摄像头，并尝试使用OpenCV拍照。

我知道可以使用以下方式来捕捉图像：

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

但它可以为我提供相机能力达到的15MP静态照片。从上面得到的远不及我通过“点击”照片所能期望的好。那么，有没有办法拍照（就像在官方WebCam软件中一样）？

- Darshan Chaudhary

你好，你看过这个之前的回答吗？如果你的相机兼容，你可以调整设置来创建更大/更清晰的图片。我会发布一个示例程序来读取相机的当前设置以及如何设置相机参数的示例。 - Steven Correia

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Steven Correia · Accepted Answer

在使用这个之前的问题作为指南进行测试后，我编写了以下程序来检查我的相机设置（Logitech S7500 USB Webcam）。我在Windows 7上使用Python 2.7和OpenCV 2.4.6。

希望您可以使用此代码作为指南，修改相机设置以获得所需的分辨率（或接近该分辨率）（使用OpenCV中的set()函数）。

如果每个相机设置的值都为0.0，则您可能无法调整相机设置。当我在笔记本电脑的内置网络摄像头上运行此程序时，我遇到了这个问题。

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)

这里是一个关于此主题的OpenCV问题链接和OpenCV文档