Cumulative Histogram

Photogrammetry-1

I had previously written about Image Histogram here:

Image Histogram

A cumulative histogram sums the number of pixels having the current value or smaller than the current value.

The following function computes the cumulative histogram

# 1. Import modules
import numpy as np
%matplotlib inline
import matplotlib.pyplot as plt
import skimage.io
from skimage import img_as_ubyte
import math

def cumulativeHistogram(hist):
    
    """The function takes as input a histogram [np.array] and returns the cumulative histogram [np.array]"""
    
    cum_hist = np.zeros((256,1))
    
    for i in range(256):
        
        cum_hist[i] = sum(hist[:i+1])
        
    return cum_hist