title: Split and Join images in Python
body: <p>I am trying to split an image using image slicer in python and then apply histogram equalization on each of them and combine them back. I am able to split the images into smaller blocks and I can see them being updated but after stitching them together I end up with the same image as the original one. Can someone point out what I am doing wrong. The file name is watch.png</p>
  
  <pre><code>import cv2
  import numpy as np
  from matplotlib import pyplot as plt
  from scipy.misc import imsave
  # import scipy
  from scipy import ndimage
  from scipy import misc
  import scipy.misc
  import scipy
  
  import sys
  import argparse
  import image_slicer
  from image_slicer import join
  
  
  img = 'watch.png'
  num_tiles = 64
  tiles = image_slicer.slice(img, num_tiles)
  
  
  
  file = "watch"
  k = 0
  filelist =[]
  for i in range(1,9):
      for j in range(1,9):
          filelist.insert(k, file+"_"+str(i).zfill(2)+"_"+str(j).zfill(2)+".png")
          k=k+1
  
  for i in range(0,num_tiles):
      img = scipy.misc.imread(filelist[i])
      hist,bins = np.histogram(img.flatten(),256,[0,256])
      cdf = hist.cumsum()
      cdf_normalized = cdf *hist.max()/ cdf.max()  
      plt.plot(cdf_normalized, color = 'g')
      plt.hist(img.flatten(),256,[0,256], color = 'g')
      plt.xlim([0,256])
      plt.legend(('cdf','histogram'), loc = 'upper left')
      cdf_m = np.ma.masked_equal(cdf,0)
      cdf_o = (cdf_m - cdf_m.min())*255/(cdf_m.max()-cdf_m.min())
      cdf = np.ma.filled(cdf_o,0).astype('uint8')
      img3 = cdf[img]
      cv2.imwrite(filelist[i],img3)
  
  
  image = join(tiles)
  image.save('watch-join.png')
  </code></pre>