一、opencv打開攝像頭修改尺寸
1、首先導入相關庫文件：
# import necessary packages
import cv2
# define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))2、接著打開攝像頭：
# open the camera
cap = cv2.VideoCapture(0)
# set the width and height of the camera capture
cap.set(3, 640)
cap.set(4, 480)3、循環讀取攝像頭畫面，完成尺寸的修改：
while(cap.isOpened()):
# read frames from the camera
ret, frame = cap.read()
if ret==True:
# resize the frame
frame = cv2.resize(frame, (800,600))
# write the resized frame
out.write(frame)
# display the resized frame
cv2.imshow('frame',frame)
# break if the 'q' key is pressed
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
# release the video capture
cap.release()
# release the video writer
out.release()
# close all the frames
cv2.destroyAllWindows()二、opencv打開攝像頭並識別圖形形狀
1、首先導入相關庫文件：
# import the necessary packages
import imutils
import cv2
# define the lower and upper boundaries of the color of the object
colorLower = (24, 100, 100)
colorUpper = (44, 255, 255)2、接著打開攝像頭：
# open the camera
cap = cv2.VideoCapture(0)3、循環讀取攝像頭畫面，完成圖形的識別：
while True:
# get a frame
ret, frame = cap.read()
# if we are unable to get a frame, this means we have reached the end of the video
if not ret:
break
# resize the frame, blur it, and convert it to the HSV color space
frame = imutils.resize(frame, width=600)
blurred = cv2.GaussianBlur(frame, (11, 11), 0)
hsv = cv2.cvtColor(blurred, cv2.COLOR_BGR2HSV)
# create a mask for the color of the object, then perform the bitwise and operation
mask = cv2.inRange(hsv, colorLower, colorUpper)
mask = cv2.erode(mask, None, iterations=2)
mask = cv2.dilate(mask, None, iterations=2)
# find contours in the mask and initialize the current (x, y) center of the object
cnts = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = imutils.grab_contours(cnts)
center = None
# if we have found at least one contour, find the largest one and compute its minimum enclosing circle
if len(cnts) > 0:
c = max(cnts, key=cv2.contourArea)
((x, y), radius) = cv2.minEnclosingCircle(c)
M = cv2.moments(c)
center = (int(M["m10"] / M["m00"]), int(M["m01"] / M["m00"]))
# if the circle is big enough, draw it and label the current shape
if radius > 10:
cv2.circle(frame, (int(x), int(y)), int(radius), (0, 255, 255), 2)
cv2.putText(frame, "Circle", (int(x-radius),int(y-radius)), cv2.FONT_HERSHEY_SIMPLEX, 0.6, (0, 255, 255), 2)
# display the resulting frame
cv2.imshow("Frame", frame)
# if the 'q' key is pressed, stop the loop
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# release the camera and close all windows
cap.release()
cv2.destroyAllWindows()三、opencv打開攝像頭代碼
使用opencv打開攝像頭代碼如下：
import cv2
cap = cv2.VideoCapture(0)
while(True):
# Capture frame-by-frame
ret, frame = cap.read()
# Display the resulting frame
cv2.imshow('frame',frame)
# if the 'q' key is pressed, stop the loop
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()四、opencv打開攝像頭沒畫面
如果打開攝像頭沒有畫面，可以檢查一下以下兩種情況：
1、檢查攝像頭是否連接好，是否以及設置為默認攝像頭；
2、修改代碼段中以下這句話：
cap = cv2.VideoCapture(0)將攝像頭的索引修改為1或其他數字，即可打開其他連接上的攝像頭。
五、opencv打開攝像頭失敗
如果打開攝像頭失敗，可以檢查以下幾個方面：
1、檢查電腦是否有許可權讀取使用攝像頭；
2、檢查電腦是否有攝像頭設備；
3、修改代碼段中以下這句話，在其後添加superuser許可權：
cap = cv2.VideoCapture(0)如下：
cap = cv2.VideoCapture(0, cv2.CAP_DSHOW)六、opencv打開攝像頭python
在python中使用opencv打開攝像頭的代碼如下：
import cv2
cap = cv2.VideoCapture(0)
while(True):
# Capture frame-by-frame
ret, frame = cap.read()
# Display the resulting frame
cv2.imshow('frame',frame)
# if the 'q' key is pressed, stop the loop
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()七、opencv打開攝像頭並捕捉圖像
使用opencv打開攝像頭並捕捉圖像的代碼如下：
import cv2
cap = cv2.VideoCapture(0)
while(True):
# Capture frame-by-frame
ret, frame = cap.read()
# Display the resulting frame
cv2.imshow('frame',frame)
# if the space bar is pressed, capture the current frame
if cv2.waitKey(1) == 32:
cv2.imwrite('image.jpg', frame)
print('Image captured')
# if the 'q' key is pressed, stop the loop
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()八、opencv打開攝像頭並保存手勢
使用opencv打開攝像頭並保存手勢的代碼如下：
# import the necessary packages
import cv2
import os
# define the paths to the training images and the output directory
imagePaths = ["images/1.jpg", "images/2.jpg", "images/3.jpg",
"images/4.jpg", "images/5.jpg", "images/6.jpg",
"images/7.jpg", "images/8.jpg", "images/9.jpg"]
outputDir = "gestures"
# loop over the training images
for imagePath in imagePaths:
# load the image, convert it to grayscale, and blur it
image = cv2.imread(imagePath)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
blurred = cv2.GaussianBlur(gray, (5, 5), 0)
# threshold the image, erode and dilate it
thresh = cv2.threshold(blurred, 60, 255, cv2.THRESH_BINARY)[1]
thresh = cv2.erode(thresh, None, iterations=2)
thresh = cv2.dilate(thresh, None, iterations=2)
# find contours in the thresholded image and sort the contours by area in descending order
cnts = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if imutils.is_cv2() else cnts[1]
cnts = sorted(cnts, key=cv2.contourArea, reverse=True)[:1]
# initialize the hull list and loop over the contours
hull = []
for c in cnts:
# compute the convex hull of the contour
hull.append(cv2.convexHull(c))
# draw the contour and convex hull of the hand
drawing = np.zeros(image.shape[:2], dtype=np.uint8)
for i in range(len(cnts)):
cv2.drawContours(drawing, cnts, i, (255, 255, 255), -1)
cv2.drawContours(drawing, hull, i, (255, 255, 255), -1)
# save the image to disk
filename = os.path.splitext(os.path.basename(imagePath))[0] + ".png"
cv2.imwrite(os.path.join(outputDir, filename), drawing)九、opencv打開攝像頭不顯示
如果打開攝像頭後沒有顯示，請檢查以下幾個方面：
1、檢查opencv是否安裝正確；
2、檢查電腦是否有攝像頭設備；
3、檢查電腦是否設置了防火牆或者殺軟是否對opencv進行了限制；
4、修改代碼段中以下這句話，添加數據類型轉換：
cv2.imshow('frame',frame)如下：
cv2.imshow('frame', np.uint8(frame))原創文章，作者：小藍，如若轉載，請註明出處：https://www.506064.com/zh-tw/n/242310.html
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