python各种读取图像方法

梦里梦外; 2022-12-21 00:51 89阅读 0赞

## 一.读取图像 ##

使用 matplotlib. image

from matplotlib import image as mping
    from matplotlib import  pyplot as plt
    import numpy as np
    img=mping.imread('美女.jpg')#image.read()
    plt.imshow(img)#图片显示
    plt.show()#画布显示
    print(type(img))
    print(img.shape)

![20201113135257774.png][] ![20201113135503472.png][]

使用 opencv

import cv2
    from matplotlib import  pyplot as plt
    import numpy as np
    img=cv2.imread('meinv (2).jpg')#
    cv2.imshow('image',img)
    cv2.waitKey(0)
    cv2.destroyAllWindows()
    print(type(img))
    print(img.shape)

![20201113140317661.png][] ![2020111314040157.png][]

import cv2
    from matplotlib import  pyplot as plt
    import numpy as np
    img=cv2.imread('meinv (2).jpg')#
    plt.imshow(img)
    plt.show()
    print(type(img))
    print(img.shape)

opencv 保存的是BGR.matplotlib保存的是RGB  
![20201113140504679.png][]

如果要正常显示为RGB需要添加

img=cv2.cvtColor(img,cv2.COLOR_BGR2RGB)#BGR-RGB

使用 PIL

from PIL import Image
    from matplotlib import  pyplot as plt
    import numpy as np
    img=Image.open('meinv (2).jpg')#
    
    plt.imshow(img)
    plt.show()
    print(type(img))
    print(img.shape)

PIL读出的图片非numpy格式  
![20201113141350174.png][]  
![20201113141426466.png][]

需要人为转换

from PIL import Image
    from matplotlib import  pyplot as plt
    import numpy as np
    img=Image.open('meinv (2).jpg')#
    img=np.array(img)
    plt.imshow(img)
    plt.show()
    print(type(img))
    print(img.shape)

![2020111314163669.png][]

## 二.缩放图像 ##

PIL 缩放

from PIL import Image,ImageOps
    from matplotlib import  pyplot as plt
    import numpy as np
    img=Image.open('meinv (2).jpg')#
    img=np.array(img)#保存为numpy
    
    img1=Image.fromarray(img)#读取numpy格式
    print(img1.size)#(670, 419)
    #缩放
    img2=img1.resize((200,200))
    print(img2.size)#(200, 200)
    
    fig=plt.figure(figsize=(12,12))
    a=fig.add_subplot(2,1,1)
    imgplot=plt.imshow(img1)
    a.set_title('before')
    
    a=fig.add_subplot(2,1,2)
    imgplot=plt.imshow(img2)
    a.set_title('after')
    plt.show()

![20201113143301906.png][]

方法二 使用numpy. resize()  
方法三 使用cv2.resize()

> 语法格式  
> cv2.resize()有很多参数，其中src和dsize必备  
> cv2.resize(src.dsize)  
> src原始图像路径  
> dsize 目标图像大小 （列，行）  
> cv2.resize(src.dsize，fx,fy)  
> fx,fy 缩放大小 比列，在dsize不用情况下。  
> b=cv2.resize(a,dszie=None,fx=0.5,fy=0.5)

import cv2
    import numpy as np
    a=cv2.imread("image\\lenacolor.png")
    b=cv2.resize(a,None,fx=1.2,fy=0.5)
    cv2.imshow("original",a)
    cv2.imshow("resize",b)
    cv2.waitKey()
    cv2.destroyAllWindows()

[20201113135257774.png]: https://img-blog.csdnimg.cn/20201113135257774.png
[20201113135503472.png]: /images/20221120/47e1a64360d44694822881de8bcbf3d3.png
[20201113140317661.png]: https://img-blog.csdnimg.cn/20201113140317661.png
[2020111314040157.png]: /images/20221120/a7a4d1e6bcb74d2c8f2256654b3d6aea.png
[20201113140504679.png]: /images/20221120/29b6a1b03d8a4428b3ac440d03b33eb1.png
[20201113141350174.png]: /images/20221120/e9cda2cfc9654063bd47fbcb91d0b69a.png
[20201113141426466.png]: /images/20221120/2ce0a2bedfb94c33a5956cd610d30e70.png
[2020111314163669.png]: /images/20221120/dc06f0c443a748be8cb98171b548b256.png
[20201113143301906.png]: /images/20221120/f91aad5f79394c80b7877551f43dce67.png