22-09-2008, 10:34 AM
An image defined in the "real world" is considered to be a function of two real variables say x,y.
Before going to processing an image, it is converted into a digital form. Digitization includes sampling of image and quantization of sampled values.
After converting the image into bit information, processing is performed.
This processing technique may be,
" Image enhancement
" Image reconstruction
" Image compression
Image enhancement refers to accentuation, or sharpening, of image features such as boundaries.
Image restoration is concerned with filtering the observed image to minimize the effect of degradations.
Image compression is concerned with minimizing the no of bits required to represent an image.
Text compression - CCITT GROUP3 & GROUP4
Still image compression - JPEG
Video image compression -MPEG
INTRODUCTION
Modern digital technology has made it possible to manipulate multi-dimensional signals with systems that range from simple digital circuits to advanced parallel computers. The goal of this manipulation can be divided into three categories:
* Image Processing image in -> image out
* Image Analysis image in -> measurements out
* Image Understanding image in -> high-level description out
Image processing is referred to processing of a 2D picture by a computer.
Basic definitions:
An image defined in the "real world" is considered to be a function of two real variables, for example, a(x,y) with a as the amplitude (e.g. brightness) of the image at the real coordinate position (x,y).
An image may be considered to contain sub-images sometimes referred to as regions-of-interest, ROIs, or simply regions. This concept reflects the fact that images frequently contain collections of objects each of which can be the basis for a region. In a sophisticated image processing system it should be possible to apply specific image processing operations to selected regions. Thus one part of an image (region) might be processed to suppress motion blur while another part might be processed to improve color rendition.
The most requirements for image processing of images is that the images be available in digitized form, that is, arrays of finite length binary words. For digitization, the given Image is sampled on a discrete grid and each sample or pixel is quantized using a finite number of bits. The digitized image is processed by a computer. To display a digital image, it is first converted into analog signal, which is scanned onto a display.
PROCESSING TECHNIQUES
" Image enhancement
" Image restoration
" Image compression etc.
Image enhancement:
It refers to accentuation, or sharpening, of image features such as boundaries, or contrast to make a graphic display more useful for display & analysis.
Image restoration:
It is concerned with filtering the observed image to minimize the effect of degradations. Effectiveness of image restoration depends on the extent and accuracy of the knowledge of degradation process as well as on filter design.
Image compression:
It is concerned with minimizing the no of bits required to represent an image.
