In [4]:

    

import numpy as np


    

In [13]:

    

a = np.zeros((4,5))
a.shape


    

    
Out[13]:





(4, 5)

In [46]:

    

a= np.arange(10)
print(a)
a[::-1]


    

    




[0 1 2 3 4 5 6 7 8 9]






    
Out[46]:





array([9, 8, 7, 6, 5, 4, 3, 2, 1, 0])

In [27]:

    

b = a.reshape(2,5)
b


    

    
Out[27]:





array([[0, 1, 2, 3, 4],
       [5, 6, 7, 8, 9]])

In [28]:

    

b[::2,::2]= -1
b


    

    
Out[28]:





array([[-1,  1, -1,  3, -1],
       [ 5,  6,  7,  8,  9]])

In [29]:

    

a


    

    
Out[29]:





array([-1,  1, -1,  3, -1,  5,  6,  7,  8,  9])

In [30]:

    

from PIL import Image


    

In [33]:

    

fimg = Image.open('../data/cameraman.tif')
fimg


    

    
Out[33]:

In [34]:

    

f = np.array(fimg)


    

In [36]:

    

f.shape


    

    
Out[36]:





(256, 256)

In [39]:

    

Image.fromarray(f[::2,::2])


    

    
Out[39]:

In [44]:

    

f[::10,:]=0
f[:,::10]=255


    

In [45]:

    

Image.fromarray(f)


    

    
Out[45]:

In [49]:

    

Image.fromarray(f[::-1,::-1])


    

    
Out[49]:

In [ ]: