The translation of the material was prepared as part of the " Python Developer. Basic " course .
Welcome! Here is the first article in the OpenCV in Python series, which, as you guessed by the name, is devoted to how to learn how to work comfortably in OpenCV.
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OpenCV
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pip install opencv-python
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import cv2
import argparse
cv2 – OpenCV. . argparse , . , (https://www.pyimagesearch.com/2018/03/12/python-argparse-command-line-arguments/), .
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ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True, help="path to input image")
args = vars(ap.parse_args())
argparse
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imread
cv2, image
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image = cv2.imread(args["image"], cv2.IMREAD_GRAYSCALE)
, – args[“image”]
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imshow. – , – .
cv2.imshow("Image", image)
cv2.waitKey(0)
cv2.waitKey(0)
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, image
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(h, w) = image.shape[:2]
# display image properties
print("width: {} pixels".format(w))
print("height: {} pixels".format(h))
OpenCV . , OpenCV , .jpeg .png.
imwrite
, , . , , OpenCV .
cv2.imwrite("folder/newimage.png", image)
:
import cv2
import argparse
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True, help="path to input image")
args = vars(ap.parse_args())
image = cv2.imread(args["image"], cv2.IMREAD_GRAYSCALE)
cv2.imshow("Image", image)
cv2.waitKey(0)
(h, w) = image.shape[:2]
# display image properties
print("width: {} pixels".format(w))
print("height: {} pixels".format(h))
cv2.imwrite("photos/newimage.png", image)
:
python app.py --image photo_one.jpeg
: app.py, photo_one.jpeg, .
, :
, , newimage.png.
OpenCV
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import cv2
import numpy as np
VideoCapture
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cap = cv2.VideoCapture(0)
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while
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while True:
ret, frame = cap.read()
cv2.imshow('video feed', frame)
cap.read()
(True/False) . , True.
cv2.imshow()
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if cv2.waitKey(1) & 0xFF == ord('q'):
break
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waitKey(0)
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0xFF
– 8- 11111111, «q». 255.
, ord(char)
, [1].
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cap.release() cv2.destroyAllWindows()
. , , :
import cv2
import numpy as np
cap = cv2.VideoCapture(0)
while True:
ret, frame = cap.read()
cv2.imshow('video feed', frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
cv2.destroyAllWindows()
, - «video feed». , «q».
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while :
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.imshow('gray feed', gray)
:
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VideoWriter
. fourcc (https://en.wikipedia.org/wiki/FourCC). FourCC – 4- , . FourCC (http://www.fourcc.org/codecs.php).
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi', fourcc, 20.0, (640, 480))
. (fps) .
, while.
out.write(frame) out.release() cv2.destroyAllWindows()
VideoWriter
.
:
import cv2
import numpy as np
cap = cv2.VideoCapture(0)
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi', fourcc, 20.0, (640, 480))
while True:
ret, frame = cap.read()
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
out.write(frame)
cv2.imshow('video feed', frame)
cv2.imshow('gray feed', gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
out.release()
cv2.destroyAllWindows()
, «output.avi» . , .
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GitHub
– 1 (https://github.com/sthitaprajna-mishra/opencv_in_python/tree/main/Part%201)
Getting Started with Videos — OpenCV-Python Tutorials 1 documentation (opencv-python-tutroals.readthedocs.io)