28-01-2013, 04:39 PM
Image processing
Image processing.ppt (Size: 856 KB / Downloads: 25)
An image may be defined as a 2-D function f (x , y), where x and y are spatial co-ordinates, the amplitude of f(x,y) is the intensity of image at that point. When x, y and |f(x,y)| are all finite, discrete quantities, we call the image as a digital image.
Analog image: It can be mathematically represented as a continuous range of values representing position and intensity. An analog image is characterized by a physical magnitude varying continuously in space. For example the image produced on the screen of a CRT monitor is analog in nature.
Digital image: It is composed of picture element called pixels. Pixels are the smallest samples of an image. A pixel represents the brightness at one point.
A digital image of N X N array elements can be treated as a 2-D signal. Converting an image into a digital format can be done either with a digital camera or by a scanner. The image is restricted in both spatial coordinates(sampling) and in its intensities (quantization).
Image sampling: sampling is the process of measuring the brightness at discrete spatial locations. A continuous image function f(x,y) can be sampled using a discrete grid of sampling points in the plane. Sampling an image at a pixel spacing distance greater than 1 results in a smaller image with some loss of information in the image. The loss increases with the increased sampling distance but the image size also decreases accordingly.