图像处理的原理

Why do we process images?
Image Processing has been developed in response to three major problems concerned
with pictures:
0 Picture digitization and coding to facilitate transmission, printing and storage
of pictures.
0 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, f (x, y), where x andy are spatial coordinates and the value off 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 Zdimensional 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: