Images are artifacts that record visual perception. Images may be two-dimensional that contain 2 axes (x and y), such as a photograph, screen display, and as well as a three-dimensional that contains 3 axes (x, y and z), such as a statue or hologram.
Images are used more than often, and images are what we mostly see in computers and designs. The vast majority of computer graphics fall into two categories: vector and bitmap. One is more complicated and time-consuming to create than the other, but both are in wide use.
Vector Image
Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics. "Vector", in this context, implies more than a straight line.
Vector graphics are based on images made up of vectors (paths or strokes) which lead through locations called control points. Each of these points has a definite 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. Each track can be assigned a color, a shape, a thickness and also a fill. 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.
This kind of image is much more sophisticated because it has more moving parts. Each vector image is made up of a handful of smaller images, just like the bitmap, except that the vector image's parts are scalable. This means that designers can change the resolution of a vector image in both directions, making a high-res image lower or making a low-res image higher. If designers are looking for an image that can be easily scaled in both directions, then their choice between vector and bitmap should be an easy one.
Something else to keep in mind in any discussion of vector and bitmap images is that the vector images are not restricted to a rectangular shape, as are the bitmap images. A designer who places a vector image on top of another image will not cover up any of the detail of the image underneath. A bitmap image does this because it is entirely made up of square pixels, even the white ones in the background that we don't realize are there. This is another point to keep in mind when choosing between vector and bitmap.
Bitmap Image
In computer graphics, a bitmap image or raster graphics image, is a dot matrix data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium. These images are stored in image files with varying formats.
A bitmap corresponds bit-for-bit with an image displayed on a screen, generally in the same format used for storage in the display's video memory, or maybe as a device-independent bitmap. A bitmap is technically characterized by the width and height of the image in pixels and by the number of bits per pixel (a color depth, which determines the number of colors it can represent).
Bitmap graphics are resolution dependent. These type of image is unable to scale up to an arbitrary resolution without loss of apparent quality. This property contrasts with the capabilities of vector graphics, which easily scale up to the quality of the device rendering them. Bitmap graphics deal more practically than vector graphics with photographs and photo-realistic images, while vector graphics often serve better for typesetting or for graphic design.
Appearances and Formats
A key point in the discussion of vector and bitmap, however, is that most widely used graphics file formats are of the bitmap variety, like GIFs, JPGs, PICTs, and TIFFs. This is because vector images lack the consistency of bitmap images in terms of photo-realism. For websites on the internet, the best choice for images is using bitmap for its photo-realistic image. Many vector images and are commonly converted to bitmap format for use on web pages. The widely known exception to this is the PDF file, which is a vector image and looks rather good when unconverted.
Examples for vector formats:
- SVG, AI, CDR, ODG, PPT, AMF, IGES, U3D, X3D, 3DXML,...
Examples for bitmap formats:
- JPEG, TIFF, GIF, PNG, BMP, ECW, IMG, RAW, PSD, PSP,...