In [1]:

    

from PIL import Image


    

In [21]:

    

im = Image.open('./open-in-nbviewer.safariextension/ipynb_icon_16x16.png')


    

In [22]:

    

im.mode


    

    
Out[22]:





'RGBA'

In [23]:

    

data = im.getdata()


    

In [24]:

    

data[0]


    

    
Out[24]:





(255, 255, 255, 0)

In [25]:

    

im.size


    

    
Out[25]:





(16, 16)

In [26]:

    

new_data = []
norm = 255 * 3
for i, d in enumerate(data):
    x = sum(d[:3])
    alpha = 255 - int(round(float(x) / float(norm) * 255.))
    new_data.append((0, 0, 0, alpha))


    

In [27]:

    

new_data[0]


    

    
Out[27]:





(0, 0, 0, 0)

In [28]:

    

im.putdata(new_data)


    

In [29]:

    

im.save('./open-in-nbviewer.safariextension/toolbar_icon_16.png')


    

In [30]:

    

!open ./open-in-nbviewer.safariextension/toolbar_icon_16.png


    

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