DIFFERENCE BETWEEN RASTER SCAN AND RANDOM
SCAN SYSTEMS
Describes the difference between raster scan and random scan system
Difference between Raster Scan and Random Scan Systems
Raster
Scan System
- In a raster scan electron beam is swept across the screen, one row at a time from top to bottom, and creates a pattern of illuminated spots.
- Its picture definition (as a set of intensity values for all the screen points) is stored in a memory area called refresh buffer or frame buffer.
- Its refreshing rate is 60 to 70 frames per second.
- It produces jagged lines that are plotted as discrete point sets.
- Resolution low
- Used to draw realistic shaded images
Random
Scan System
- In a random scan, the electron beam is directed only to the parts of the screen where a picture is to be drawn.
- Its picture definition is stored as a set of line-drawing commands in an area of memory referred to as a refresh display file or display list.
- Its refreshing rate is 30 to 60 lines per second.
- It produces smooth line drawing.
- Resolution high.
- Used to draw line drawing applications.
