Vector
graphics are based on describing objects mathematically. Vector graphics are also
called ‘object-orientated’ or ‘object’ graphics.
Vector
graphics are made by CAD ( computer aided design ) programs, Corel Draw and
other draw packages eg inside WORD.
Vector
displays are VDUs (visual display units) that plot points on the screen and
draw the lines.
Raster
displays consist of individually drawn horizontal lines of pixels. Raster is
used on all television displays.
More
memory is needed for raster than vector displays and they are slower. The VDU screen
needs to be refreshed about 30 times a second to stop the appearance of
flickering.
A
bitmap is an exact pixel-by pixel copy of a raster graphic image. Bit-mapped
graphics are created by paint programs eg Paint Shop Pro.
Interlacing
refreshes the screen in two separate cycles by tracing alternate lines.
Graphics
digitisers convert non-digital images into digital bitmaps eg scanners.