Topics Covered: 1. Introduction to computer Graphics 2 Graphics Primitives: Pixel, Resolution, Aspect Ratio, Frame Buffer 3. Display Devices: Monochrome Display Monitor, Color Display Monitor, Raster Graphics Display 4. Applications

1. Computer Graphics Basic, OpenGL and Line,
Circle Drawing
Topic
Introduction to computer Graphics
and graphics primitives
By,
Dr. Dipika Birari

2. Contents
• Introduction
• Graphics Primitives
– Pixel
– Resolution
– Aspect Ratio
– Frame Buffer
• Display Devices
– Monochrome Display Monitor
– Color Display Monitor
– Raster Graphics Display
• Applications

3. Introduction
Example: Graph
Any thing which is not a text on computer is treated as a Computer
Graphics
Computer: The computer is a data processing machine or tool which is
used for storing, manipulating and displaying data
Graphics: Visualization of that data.
0
20
40
60
80
100
F.E. S.E. T.E. B.E.
Result
Result

4.  Business software
 T.V. Channels
 GUI and Animations
 Making charts
 Image Processing
 CAD/CAM
 Computer Games
Applications

5. Contents
• Introduction
 Graphics Primitives
– Pixel
– Resolution
– Aspect Ratio
– Frame Buffer

6. Pixel
Graphics Primitives
The Pixel is the smallest addressable screen element.
Pixel is the smallest piece of a display screen which we can control.
Pixel
Name Address
has
1 2 3 4 5
1
2
3
4
5
Coordinates: (I,j) =(Row, Column)= (3,3)
The greater the number of
points, the higher is the
resolution

7. Resolution
Resolution: Number of dots on the screen
Graphics Primitives
( No. of dots on horizontal line , No of dots on vertical line)
Pair of
Example,
1. 640 X 480
2. 800 X 600
3. 1024 X 768
4. 1280 X 1024
R G
B
RGB Model
This produce up to 16 millions possible colors
Color Range
= 0 to 255

8. Aspect Ratio
In Imaging, aspect ratio is the width of image divided by it’s height.
• Aspect Ratio= 2:1 means width is twice as large as height.
• While resizing image, maintain the Aspect Ratio to avoid stretching.
Aspect Ratio = 8 /6
= 1.33
Graphics Primitives
Aspect Ratio = Width / Height
8 Inches
6 Inches

9. Frame Buffer
• It collects and stores pixel values for use by the display device.
• It consists of color values for every pixel on the screen.
• Color values are stored in
 1-bit : 2 colors (B &W, Binary , Monochrome)
 4-bit s: 16 colors
 8-bit s: 256 colors
 16-bits: 32 thousand colors
 24-bit s: 16 million (High color formats )
 32 bits: Latest (True color formats )
Graphics Primitives
“ An array, which contains an internal representation of the image is
called Frame Buffer.”

10. Frame Buffer
If color value is
Graphics Primitives
1 For more number
of color values
Black & White
Frame Buffer
Color Frame
Buffer
Total amount of
memory required to
drive frame buffer
Resolution of output signal
Color depth size
depends
on

11. Contents
• Display Devices
– Monochrome Display Monitor
– Color Display Monitor
– Raster Graphics Display
• Applications

12. Display Devices
• There are several hardware devices used to display images to locate
and display, the points & line segments.
• Two types
Monochrome Display Monitor
Color Display Monitor

13. • Monochrome Display Monitor
It consist a Cathode Ray Tube(CRT) along with circuits.
Display Devices (Cont…)

14. • The light given off by the phosphor during exposure to the electron
beam is known as fluorescence.
• The continuing glow given off after the beam is removed known as
phosphorescence.
• The duration of phosphorescence is known as the phosphors
persistence.
Display Devices (Cont…)

15. Vertical and Horizontal Retrace
Display Devices (Cont…)
Horizontal Plate: Controls the
beam to scan from left to right and
retrace from right to left.
Vertical Plate: Controls the beam to
go from first scan line at the top to
the last scan line at the bottom and
retrace from bottom back to top.

17. • Color Display Monitor
Display Devices (Cont…)
• It contains 3 electron
guns instead of one
with one electron gun
for each primary color.
• These phosphors are
capable of emitting
Red, Green and Blue
light.

18. Raster Graphics Display
• To store the information for each pixel in computer’s memory, a lot of
memory may be required. This is done in raster graphics display.
Each
pixel
At least one bit Further bits
Intensity Information
light or dark
If shades of different
colors are defined

19. • A portion of system memory which is used to hold the pixels is called
as Frame Buffer.
Raster Graphics Display
User Program Frame Buffer Raster Display
Raster Display Device
Lines / Surfaces
Color images
Display

20.  Business software
 T.V. Channels
 GUI and Animations
 Making charts
 Image Processing
 CAD/CAM
 Computer Games
Applications