import numpy as np
import matplotlib.pyplot as plt
from scipy import misc as mc

def getHist(img, n):
    H = np.zeros(n)
    width, height = img[:,:].shape
    space = np.linspace(0, 255, n+1);
    #print space
    for i in range(0, n):
        boolM =  ( ((img[:,:] >= space[i]) & (img[:,:] < space[i+1])) | ((space[i+1]==255) & (img[:,:] >= space[i]) & (img[:,:] <= space[i+1])) )
        H[i] = np.sum(boolM)
    return H

def getProperties(img):
    width, height = img[:,:,0].shape;
    brightness =  float(np.sum(img[:,:,0]))/(width*height)
    contrastMat = img[:,:,0]-brightness
    contrastMat = contrastMat * contrastMat
    contrast = np.sqrt(float(np.sum(contrastMat))/(width*height))
    return brightness, contrast

#

A = np.array([[1, 0, 0.25], [1, 0.75, 0.5], [1, 0.5, 0.25]]) * 255.0
print getHist( A, 3 ) # [3 2 4]
print getHist( A, 5 ) # [1 2 2 1 3]

img = mc.imread('lab2.png')
img = img.astype("float64")
H = getHist(img[:,:,0],11)


plt.subplot(1,2,1)
plt.bar(range(len(H)), H);

img = img/255
plt.subplot(1,2,2)
plt.imshow(img)

plt.show()