Computer Graphics Multimedia Abhishek Khare UNITI Computer Graphics

Computer Graphics & Multimedia Abhishek Khare

UNIT-I • Computer Graphics : definition, classification & Applications, Development of Hardware & Software for Computer Graphics. • Display devices, Hard copy devices. Interactive Input devices, display processor, • Line drawing; various algorithms and their comparison, circle generation- Bresenham’s mid point circle drawing algorithm, mid point ellipse drawing algorithm Computer Graphics-2015 @Copyright Abhishek Khare 2

Suggested Book Computer Graphics-2015 @Copyright Abhishek Khare 3

What is Computer Graphics? Computer graphics remains one of the most existing and rapidly growing computer fields. Computer graphics may be defined as a pictorial representation or graphical representation of objects in a computer. Computer Graphics-2015 @Copyright Abhishek Khare 4

Aplication of Computer Graphics? q Computational biology q Computational physics q Computer-aided design q Computer simulation q Digital art q Education q Graphic design q Information visualization q Rational drug design q Scientific visualization q Video Games q Virtual reality q Web design Computer Graphics-2015 @Copyright Abhishek Khare 5

Assignment-1 • Development of Hardware & Software for Computer Graphics • Display devices, Hard copy devices • Interactive Input devices, display processor Computer Graphics-2015 @Copyright Abhishek Khare 6

What is resolution? • The maximum number of points that can be displayed without overlap on a CRT is referred to as the resolution. What is Aspect ratio? • The ratio of vertical points to the horizontal points necessary to produce length of lines in both directions of the screen is called the Aspect ratio. Usually the aspect ratio is ¾. Computer Graphics-2015 @Copyright Abhishek Khare 7

Define pixel? • Pixel is shortened forms of picture element. Each screen point is referred to as pixel or pel. What is frame buffer? • Picture definition is stored in a memory area called frame buffer or refresh buffer. Computer Graphics-2015 @Copyright Abhishek Khare 8

Display devices Raster and random scan display Computer Graphics-2015 @Copyright Abhishek Khare 9

Random scan display • Random scan monitors draw a picture one line at a time and for this reason are also referred to as vector displays strokewriting or calligraphic displays. • The component lines of a picture can be drawn and refreshed by a random-scan system in any specified order. • Refresh rate on a random-scan system depends on the number of lines to be displayed. • Picture definition is now stored as a set of line-drawing commands in an area of memory referred to as the refresh display file. Computer Graphics-2015 @Copyright Abhishek Khare 10

Contd. • Sometimes the refresh display file is called the display list, display program, or simply the refresh buffer. • To display a specified picture, the system cycles through the set of commands in the display file, drawing each component line in turn. After all linedrawing commands have been processed, the system cycles back to the first line command in the list. • Random-scan displays are designed to draw al the component lines of a picture 30 to 60 times each second. Computer Graphics-2015 @Copyright Abhishek Khare 11

RASTER-SCAN DISPLAYS • In a raster- scan system, the electron beam is swept across the screen, one row at a time from top to bottom. • As the electron beam moves across each row, the beam intensity is turned on and off to create a pattern of illuminated spots. • Picture definition is stored in memory area called the refresh buffer or frame buffer. Computer Graphics-2015 @Copyright Abhishek Khare 12

Contd. • This memory area holds the set of intensity values for all the screen points. Stored intensity values are then retrieved from the refresh buffer and “ painted” on the screen one row (scan line) at a time. • Each screen point is referred to as a pixel or pel (shortened forms of picture element). Computer Graphics-2015 @Copyright Abhishek Khare 13

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Technique to produce colour display with a CRT • Beam penetration method • Shadow mask method Computer Graphics-2015 @Copyright Abhishek Khare 15