## Motivation

Histogram is the process of visual representation of frequency distribution with a bar plot. In computer vision, an image histogram is the process of representation of the frequency of intensity values with a bar plot. With image histogram equalization, we can easily adjust the distribution of frequency values of the image intensities. Generally, the process helps us to increase the contrast and brightness of an image. The process is simple and easy to implement. This article will discuss the full process of histogram equalization along with coding examples.

## Table of Contents

## Image Histogram

** Image histogram **is the representation of the frequency of image intensity values with a bar plot. In Fig -1, I have shown a sample image with its intensity values in a 2D space.

The values range from 0 to 7. Letâ€™s calculate the frequency of the values.

An ** image histogram** is a simple representation of the

*frequency*against the

*intensity value*with a bar plot, as shown in

*Fig-3*.

## Full Process of Histogram Equalization

Histogram equalization is the process of uniformly distributing the frequency of the image intensity values with the help of some functions. Mainly the functions are probability function â€” **PDF (Probability Density Function) and CDF (Cumulative Distribution Function).**

**PDF**is calculated with the frequency of an intensity value divided by the total frequency.**CDF**holds the probability of a probability distribution less than or equal to a particular value. For example, PDF of the intensity value*0 â†’ 0.12, 1 â†’ 0.24, 2 â†’ 0.12, etc. So, CDF for 1 is 0.12+0.24 = 0.36, 2 is 0.36+ 0.12=0.48, and so on.*