idftshift function

In [1]:

    

%matplotlib inline
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np
import sys,os
ia898path = os.path.abspath('/etc/jupyterhub/ia898_1s2017/')
if ia898path not in sys.path:
    sys.path.append(ia898path)
import ia898.src as ia

ia636path = os.path.abspath('/home/lotufo/ia636/ia636/')
if ia636path not in sys.path:
    sys.path.append(ia636path)
testing = (__name__ == "__main__")


    

In [54]:

    

def Copy_of_4_slices(f):
    f_array = np.asarray(f)
    fx2 = np.concatenate((f_array,f_array),axis=1)
    fx4 = np.concatenate((fx2,fx2))
    return fx4


    

In [53]:

    

def Copy_of_4_ImagesDepth(f):
    f_array = np.asarray(f)
    fx2 = np.concatenate((f_array,f_array),axis=1)
    fx4 = np.concatenate((fx2,fx2))
    fx4Depth = np.dstack((fx4,fx4))
    return fx4Depth


    

In [52]:

    

def ptrans(f,t):
    g = np.empty(f.shape)
    if f.ndim == 1:
        w = len(f);
        ti=t
        ti = (-t + w) % w # mapeamento inverso para w com translação en t (eixo X)
        fx2 = np.append(f, f)
        g = fx2[ti:ti+w]
    elif f.ndim == 2: 
        h,w = f.shape
        ti = t;
        ti[0] = (-t[0] + h) % h # mapeamento inverso para h com translação en t[0] (eixo Y)
        ti[1] = (-t[1] + w) % w # mapeamento inverso para w com translação en t[1] (eixo X)
        i4 = Copy_of_4_slices(f)
        g = i4[ti[0]:ti[0]-h,ti[1]:ti[1]+w]
    elif f.ndim == 3:
        z,h,w = f.shape
        ti = t
        ti[0] = (-t[0] + z) % z # mapeamento inverso para z com translação en t[0] (eixo Z)
        ti[1] = (-t[1] + h) % h # mapeamento inverso para h com translação en t[1] (eixo Y)
        ti[2] = (-t[1] + w) % w # mapeamento inverso para w com translação en t[2] (eixo X)
        i4 = Copy_of_4_ImagesDepth(x3d)
        g = i4[ti[0]:ti[0]+z,ti[1]:ti[1]-h,ti[2]:ti[2]+w]
    return g


    

In [51]:

    

if testing:    
    l = np.array([1,2,3,4,5,6])
    x=np.array([[1,2,3],[4,5,6],[7,8,9]])
    x3d = x.reshape(1,x.shape[0],x.shape[1])
    print('teste 1 d')
    %timeit ptrans(l,3)
    %timeit ia.ptrans(l,3)
    print('teste 2 d')
    %timeit ptrans(x,[1,2])
    %timeit ia.ptrans(x,[1,2])
    print('teste 3 d')
    %timeit ptrans(x3d,[1,2,1])
    %timeit ia.ptrans(x3d,[1,2,1])


    

    




teste 1 d
The slowest run took 9.57 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 8.03 µs per loop
The slowest run took 6.80 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 11 µs per loop
teste 2 d
The slowest run took 4.86 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 9.5 µs per loop
10000 loops, best of 3: 49.9 µs per loop
teste 3 d
The slowest run took 4.57 times longer than the fastest. This could mean that an intermediate result is being cached.
10000 loops, best of 3: 19.1 µs per loop
10000 loops, best of 3: 62.7 µs per loop

In [50]:

    

if testing:    
    f = mpimg.imread('/home/lotufo/ia898/data/cameraman.tif')
    g1= ptrans(f, np.array(f.shape)//3)
    g2 =ia.ptrans(f, np.array(f.shape)//3)
    nb = ia.nbshow(2)
    nb.nbshow(g1,title='ptrans')
    nb.nbshow(g2,title='ia.ptrans')
    nb.nbshow()
    print('teste')
    %timeit ptrans(f,np.array(f.shape)//3)
    %timeit ia.ptrans(f,np.array(f.shape)//3)


    

    





                
                    
                    
ptrans
                    
                    
ia.ptrans







    




teste
The slowest run took 21.42 times longer than the fastest. This could mean that an intermediate result is being cached.
10000 loops, best of 3: 62.3 µs per loop
100 loops, best of 3: 2.26 ms per loop

In [34]:

    

def dftshift(f):
    return ptrans(f, np.array(f.shape)//2)


    

In [49]:

    

def idftshift(f):
    return ptrans(f, np.ceil(-np.array(np.shape(f))/2).astype(np.int))


    

In [48]:

    

f = mpimg.imread('/home/lotufo/ia898/data/cameraman.tif')
F = ia.dft(f)
Fs = ia.dftshift(F)
Fs1 = dftshift(F)
iFs1 = idftshift(Fs1)
ia.adshow(ia.dftview(F))
ia.adshow(ia.dftview(Fs))
ia.adshow(ia.dftview(Fs1))
ia.adshow(ia.dftview(iFs1))