Digital Signal and Image Processing Using MATLAB

Chapter 6

An Introduction to Image Processing

This chapter provides the reader with a few elements on image processing with MATLAB^®, which comes equipped with 2D (two dimension) functions, necessary when working in this field, a field not too different from 1D signal processing.

This chapter is merely an introduction. The reader can benefit from reading [31], a rather extensive overview of what is done with images, both still and animated. Some important problems, related to sampling, rectangular, hexagonal or of another kind, to perception, to content aspects in terms of objects, etc., will not be discussed here. The only thing we will be dealing with is handling two dimension arrays. We will also explain how to program some of the functions contained in the “image” toolbox.

Examples in this chapter are illustrated by figures that cannot perfectly render the phenomena we are trying to underline. The printing process, whether monochrome or not, adds its own imperfections (quantization, weaving, number of colors, color transcription, etc.) when rendering images. In fact, every part of the digital processing chain, from the data recording device to the printer, has a role that will not be covered in this book.

6.1   Introduction

6.1.1   Image display, color palette

From now on, an image will be considered as a set of pixels (the contraction of picture element), associated with a rectangular grid of the original image (Figure 6.1).

In MATLAB^®, there are several ways to display an ...