OPENCV-python 第一天（python opencv3）

Jupyter notebook

# To add a new cell, type '# %%'
# To add a new markdown cell, type '# %% [markdown]'
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from IPython import get_ipython


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import numpy as np
print(np.zeros([2,3]))


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import cv2
print(cv2.__version__)


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#opencv 设有opencv-python 和opencv-contrib-python
#opencv-python opencv-contrib-python pytesseract
# pip install  opencv-python=3.4.20.35 opencv-contrib-python=3.4.20.35 pytesseract
#上述已经给了


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import cv2 as cv
import numpy as np 
import matplotlib.pyplot as plt
get_ipython().run_line_magic('matplotlib', 'inline')


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img = cv.imread('./images/car.png')
cv.namedWindow('CAR',cv.WINDOW_AUTOSIZE)
cv.imshow('CAR',img)
cv.waitKey(0)
cv.destroyAllWindows()


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img.shape


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img.dtype


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type(img)


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img2= img.reshape(1650,949,1)
cv.imshow('new',img2)
cv.waitKey(0)
cv.destroyAllWindows()


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img


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#显示图像信息
def showImg(name,img):
    cv.imshow(name,img)
    cv.waitKey(0)
    cv.destroyAllWindows()


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h,w,c= img.shape


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np.zeros((3,4),np.uint8)


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np.array(
    [
        [[1,2],[3,4]],
        [[1,3],[2,4]],
        [[4,2],[3,1]]
    ]
)


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for row in range(h):
    for col in range(w):
        for ch in range(c):
            img[row,col,ch]=100
img[:,:,1]=255
showImg('new',img)


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gray_img = cv.imread('./images/lena.jpg',cv.IMREAD_GRAYSCALE)
showImg('gray_imag',gray_img)


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gray_img.shape


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#读取视频
videos = cv.VideoCapture('./images/test.mp4')
if videos.isOpened():
    ret,frame = videos.read()
else:
    ret =False   


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while ret:
    ret,fram = videos.read()
    if frame is  None:
        break
    if ret==True:
        gray = cv.cvtColor(fram,cv.COLOR_BGR2GRAY)
        cv.imshow('gray',gray)
        k=cv.waitKey(50)
        if k&0xff==27:
            break
videos.release()
cv.destroyAllWindows()


# %%
# ROI  截取图片
cat = cv.imread("./images/cat.jpg")
cv.imshow('cat',cat)
cat_block = cat[0:200,0:250]
showImg('cat_block',cat_block)
cv.waitKey(0)
cv.destroyAllWindows()


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#获取通道数
b,g,r = cv.split(cat)


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b #每一行的中每个点的B通道像素


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cat


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