Embedded Signal Processing with the Micro Signal Architecture

Chapter 10

Practical DSP Applications: Digital Image Processing

Image processing is an important application of two-dimensional (2D) signal processing. Because of the developments of fast, low-cost, and power-efficient embedded signal processors for real-time processing, digital image processing is widely used in portable consumer electronics such as digital cameras and picture phones. This chapter introduces basic concepts of digital image processing and some simple applications.

10.1    OVERVIEW OF IMAGE REPRESENTATION

A digital image (or picture) is visual information received, represented, processed, stored, or transmitted by digital systems. With advancements in microelectronics, digital image processing is widely used for applications such as enhancement, compression, and recognition. Digital image processing has many characteristics in common with one-dimensional (1D) signal processing introduced in previous chapters.

As discussed in Chapter 2, 1D digital signals are denoted by x(n), which represents the value (amplitude) of signal x at discrete time n. Digital images are 2D signals that consist of picture elements called pixels. Each pixel can be represented as x(m,n), where m is the row (height) index from 0 to M − 1 (top to bottom), n is the column (width) index from 0 to N − 1 (left to right), and x(m,n) is the value of 2D space function x at the pixel location (m,n). Therefore, each digital image can be represented by M × N pixels. Similar to the 1D sampling theorem ...