Why do we process images? Image Processing has been developedin response to three major problems concerned with pictures: Picture digitization and coding to facilitate transmission, printing and storage of pictures. Picture enhancement and restoration in order, for example, to interpret more easily pictures of the surface of other planets taken by various probes. Picture segmentation and description as an early stage in Machine Vision. | Image Processing The Fundamentals. Maria Petrou and Panagiota Bosdogianni Copyright 1999 John Wiley Sons Ltd Print ISBN 0-471-99883-4 Electronic ISBN 0-470-84190-7 Chapter 1 Introduction Why do we process images Image Processing has been developed in response to three major problems concerned with pictures Picture digitization and coding to facilitate transmission printing and storage of pictures. Picture enhancement and restoration in order for example to interpret more easily pictures of the surface of other planets taken by various probes. Picture segmentation and description as an early stage in Machine Vision. What is an image A monochrome image is a 2-dimensional light intensity function a y where x and y are spatial coordinates and the value of f at x y is proportional to the brightness of the image at that point. If we have a multicolour image f is a vector each component of which indicates the brightness of the image at point x y at the corresponding colour band. A digital image is an image f x y that has been discretized both in spatial coordinates and in brightness. It is represented by a 2-dimensional integer array or a series of 2-dimensional arrays one for each colour band. The digitized brightness value is called the grey level value. Each element of the array is called a pixel or a pel derived from the term picture element . Usually the size of such an array is a few hundred pixels by a few hundred pixels and there are several dozens of possible different grey levels. Thus a digital image looks like this f y 0 0 1 0 0 1 1 1 0 7V-l -I 1 7V-1 L JV-1 O 2V 1 1 . f N - 1 N - 1 J 2 Image Processing The Fundamentals with 0 f x y G 1 where usually N and G are expressed as integer powers of 2 W 2 G 2ro . What is the brightness of an image at a pixel position Each pixel of an image corresponds to a part of a physical object in the 3D world. This physical object is illuminated by some light which is partly reflected and partly absorbed by it. Part of the .
