9.2

'''
Napisati funkciju gaussBandStopFilter koja implementira Gausov filtar nepropusnik opsega dat formulom:

gde su  (u,v)  prostorne koordinate DFT slike,  D  je euklidsko rastojanje posmatrano od sredine slike,  D0  je poluprečnik a  W  širina prstena.

Definisanim filtrom filtrirati periodičnu smetnju prisutnu u slici moon_periodic.png. Dodatno prikazati amplitudsku karakteristiku filtra, 3D prikaz i poprečni presek.
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Napomena: Za eventualne probleme deljenja sa 0 koristiti np.finfo('float').eps.
'''
def gaussBandStopFilter(H_size,D0,W):
  u = np.arange(H_size[0]).reshape(-1, 1) - np.floor(H_size[0]/2)
  v = np.arange(H_size[1]) - np.floor(H_size[1]/2)

  D = np.sqrt(u**2 + v**2)
  H = 1-np.exp(-0.5*((D**2-D0**2)/(D*W + np.finfo('float').eps))**2)
  return H

import numpy as np

print(np.finfo('float').eps)

import plotly.express as px
from skimage import io

img = io.imread('moon_periodic.png')
fig = px.imshow(img, color_continuous_scale='gray')
fig.show()

IMG = np.fft.fftshift(np.fft.fft2(img, s=(2*img.shape[0],2*img.shape[1])))
fig = px.imshow(np.log(np.abs(IMG)+1), color_continuous_scale='gray')
fig.show(config={'modeBarButtonsToAdd':['drawline',
                                        'drawopenpath',
                                        'drawcircle',
                                        'eraseshape']})

print(np.sqrt((256-128)**2+(256-216)**2))

H = gaussBandStopFilter(IMG.shape, 134, 5)
fig = px.imshow(np.abs(H), color_continuous_scale='gray')
fig.show()

import plotly.graph_objects as go
from plotly.subplots import make_subplots

fig = make_subplots(rows=1, cols=2, specs=[[{'type': 'surface'}, {'type': 'scatter'}]])

fig.add_trace(go.Surface(z=np.abs(H)), row=1, col=1)
fig.add_trace(go.Scatter(y=np.abs(H)[256], mode='lines'), row=1, col=2)
fig.show()

IMG1 = IMG * H
fig = px.imshow(np.log(np.abs(IMG1)+1), color_continuous_scale='gray')
fig.show()

img1 = np.real(np.fft.ifft2(np.fft.ifftshift(IMG1)))
img1 = img1[:img.shape[0],:img.shape[1]]

fig = px.imshow(img1, color_continuous_scale='gray')
fig.show()