3. Working with Histograms

Overview

In this chapter, you will learn about histograms and the adjustment of image histograms to enhance subtle details such as the appearance of objects hidden in shadows and the improvement of contrast in dark images. Although image histograms are simple, you will find that they are really powerful tools for enhancing an image to achieve contrast adjustment and better visualization. In almost all of your image enhancement projects, histogram equalization will be an important step. You will test your knowledge with exercises and an end-of-chapter activity, where you will draw a rectangular bounding box on an image and enhance the contrast within that box. By the end of this chapter, you will be able to plot histograms of different channels of an image and equalize histograms of grayscale and color images using different methods.