title: Calculating Energy of image frame using DWT in python shows wrong value
body: <p>I want to find the energy of the image frame. 
  This is how I calculated in Matlab.</p>
  
  <pre><code>[~,LH,HL,HH] = dwt2(rgb2gray(maskedImage),'db1'); % applying dwt 
  E = HL.^2 + LH.^2 + HH.^2;    % Calculating the energy of each pixel.
  Eframe = sum(sum(E))/(m*n); % m,n row and columns of image.
  </code></pre>
  
  <p>when I programmed in python for the same image, the value of Energy is shown 170 for expected 0.7 
  where did my program go wrong please suggest</p>
  
  <pre><code>#!usr/bin/python
  import numpy as np
  import cv2
  import pywt
  im = cv2.cvtColor(maskedimage,cv2.COLOR_BGR2GRAY)
  m,n = im.shape
  cA, (cH, cV, cD) = pywt.dwt2(im,'db1')
  # a - LL, h - LH, v - HL, d - HH as in matlab
  cHsq = [[elem * elem for elem in inner] for inner in cH]
  cVsq = [[elem * elem for elem in inner] for inner in cV]
  cDsq = [[elem * elem for elem in inner] for inner in cD]
  Energy = (np.sum(cHsq) + np.sum(cVsq) + np.sum(cDsq))/(m*n)
  print Energy
  </code></pre>