notebook.community

Edit and run



In [1]:

    
%run ../common.ipynb









    



Populating the interactive namespace from numpy and matplotlib

Read image



In [2]:

    
img = imread('mp.tif')

Find the center



In [3]:

    
center_x, center_y = [ x/2 for x in img.shape ]

Create a hann window mask



In [4]:

    
x, y = np.meshgrid(range(img.shape[1]), range(img.shape[0]))
r = np.sqrt((center_x - x)**2 + (center_y - y)**2)
mask = (np.cos(r/center_x*np.pi)+1)/2
mask[r>center_x] = 0

Apply the window and show images



In [6]:

    
wimg = img * mask
imshow(img)
imshow(wimg);

Do Fourier transform



In [7]:

    
fimg = fftshift(fft2(img))
fwimg = fftshift(fft2(wimg))

Show the difference of FT with and without Hann window



In [8]:

    
imshow(log(abs(fimg)), cmap="gray")
imshow(log(abs(fwimg)), cmap="gray");