Python，OpenCV：从网络摄像头捕获图像
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Python, OpenCV : Capture Images from WebCam
提问by Darshan Chaudhary
I have a Logitech C920 hooked to my PC and am trying to use it to click pictures using OpenCV.
我有一台 Logitech C920 连接到我的 PC，我正在尝试使用它来使用 OpenCV 单击图片。
I know that I can capture images using :
我知道我可以使用以下方法捕获图像：
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
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 clickpictures.
但它让我获得了我的相机能够拍摄的 15MP 静态摄影。我从上面得到的远不如我click想象的那样。
So, is there a way to take pictures (like it can be done in the official WebCam software) ?
那么，有没有办法拍照（就像在官方网络摄像头软件中可以做到的那样）？
回答by Steven Correia
After testing with this previous questionas 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.
在以上一个问题为指导进行测试后，我编写了以下程序来检查我的相机设置（罗技 S7500 USB 网络摄像头）。我在 Windows 7 上使用 Python 2.7 和 OpenCV 2.4.6。
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.)
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得所需的分辨率（或接近分辨率）（使用set()OpenCV 中的功能。）
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.
如果您将每个相机设置的值全部设为 0.0，则您可能无法调整相机设置。我在笔记本电脑的内置网络摄像头上运行此程序时遇到了这种情况。
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)
Hereis a link to an OpenCV question about this topic and the OpenCV Documentation
这是有关此主题的 OpenCV 问题和OpenCV 文档的链接
