python pillow 处理图片

demo1

#打开图片，并随机添加一些椒盐噪声
from PIL import Image
import numpy as np
import matplotlib.pyplot as plt
img=np.array(Image.open('/home/keysen/caffe/examples/images/cat.jpg')) #打开图像并转化为数字矩阵

#随机生成5000个椒盐
rows,cols,dims=img.shape
for i in range(5000):
    x=np.random.randint(0,rows)
    y=np.random.randint(0,cols)
    img[x,y,:]=255

plt.figure("cat_salt")
plt.imshow(img)
plt.axis('off')
plt.show()

demo2

#将图像二值化，像素值大于128的变为1，否则变为0
from PIL import Image
import numpy as np
import matplotlib.pyplot as plt
img=np.array(Image.open('/home/keysen/caffe/examples/images/cat.jpg').convert('L')) #打开图像并转化为数字矩阵

rows,cols=img.shape
for i in range(rows):
    for j in range(cols):
        if (img[i,j]<=128):
            img[i,j]=0
        else:
            img[i,j]=1

plt.figure("cat_black&white")
plt.imshow(img,cmap='gray')
plt.axis('off')
plt.show()

参考：
https://blog.csdn.net/Hanging_Gardens/article/details/79014160