Digital imaging or digital image acquisition is the creation of digital images. The termis often assumed to imply or include the processing, compression, storage, printing,and display of such images. The most usual method is by digital photography with adigital camera but other methods are also employed.Digital imaging was developed in the 1960s and 1970s. As digital technology becamecheaper in later decades it replaced the older film methods for many purposes. Animage changed on the computer would be called a digital image e.g. If a photographwas taken (which would be a natural photo) and then the person who took the photowanted to tweak it, he would have to put it on a computer. After he finishes tweakingthe photo it becomes a digital image instead of a natural image.
Raster Images A raster image, also called a bitmap, is a way to represent digital images. The raster image takes a wide variety of formats, including the familiar .gif, .jpg, and .bmp. A raster image represents an image in a series of bits of information which translate into pixels on the screen. These pixels form points of colour which create an overall finished image. When a raster image is created, the image on the screen is converted into pixels. Each pixel is assigned a specific value which determines its colour. The raster image system uses the red, green, blue (RGB) colour system. In photographs with subtle shading, this can be extremely valuable.
Vector Images Vector images are created on a computer using mathematical calculations. Vector images are used for simple geometric shapes like lines and arcs. These shapes can be combined to make squares and circles. Vector graphics is based on images made up of vectors which lead through locations called control points. Each of these points have a position on the x and y axes of the work plan. Each point, as well, is a variety of database, including the location of the point in the work space and the direction of the vector (which is what defines the direction of the track. This does not affect the size of the files in a substantial way because all information resides in the structure; it describes how to draw the vector.
Raster VS VectorUsually when choosing one of these image types the user would choose Vector images over Raster. This would usually be the case because Raster images are bury when magnified while Vector images are usually defined. As you can see with the image below Raster images have a blurred edge.
Image file FormatsImage file formats are standardize means of organizing and storing digital images. ImageFiles are made up of digital data which can be rasterized for use on a computer display. Animage file format can store data in uncompressed, compressed or vector formats. Once animage is formed the image becomes a grid of pixels, each of which has a number of bits todesignate its colour equal to the colour depth of the device displaying it. A raster image fileformat can be displayed in many different formats, e.g.Jpeg, Exif, Tiff, Raw, Png, Gif,Bmp, Ppm, Webp, Jpeg 2000.
Jpeg file formatThe Jpeg file format is one of the most common image file formats used around the world.One of the main advantages of the Jpeg file format is that it is smaller in file size then mostother image file formats. A disadvantage of the jpeg file format is that due to its small size itloses depth and quality.Gif file formatGif was the first image file format introduced into the world wide web. One of theadvantages of having the Gif file format is that it is html supported. One of thedisadvantages of the Gif File format is that it has restricted file colours.
Tif File formatThe Tiff file format is an image file format that mainly graphic designers use. It is aflexible and adaptable file format. The Tiff file is widely used as a bitmapped fileformat, which stores graphics in CMYK or RGB colour model. One of theadvantages of using the Tiff format is that it is good for storing information forprinting. A disadvantage. of using the Tiff format is that it takes up quite a lot ofroom up on the hard drive compared to other file formats.
References http://en.wikipedia.org/wiki/JPEG http://en.wikipedia.org/wiki/Graphics_Interchange_F ormat http://en.wikipedia.org/wiki/Tagged_Image_File_For mat