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1. AMITY UNIVERSITY, HARYANA
COMPUTER GRAPHICS
AnkIT GARG
ASSISTAnT PROfESSOR
AMITy UnIvERSITy, HARyAnA

2. 30/9/2008 Lecture 2 2
Character Generation Techniques
Computer Graphics

3. 30/9/2008 Lecture 2 3
Characters Generation in CG
– In computer graphics character can be generated using software.
– In hardware implementation of character generation limited faces of
character can be generated.
– A wide variety of faces of character can be generated with software
implementation.
– There are three methods for generating characters using software
implementation.
– Stroke method
– Vector method or bitmap method.
– Star bust method

4. 30/9/2008 Lecture 2 4
Stoke method
• In this method we use a sequence of line drawing function and arc
functions to generate characters.
• We can generate a sequence of character by assigning starting and
end point of line or arc.
• By using this method various faces of character can be generated
by changing the values (parameters) in line and arc function.

5. 30/9/2008 Lecture 2 5
Stoke method
• The main disadvantage of this method is when we draw a diagonal line it
produce aliased character.

6. 30/9/2008 Lecture 2 6
Bitmap Method

7. Program For Bitmap Method
• #include<stdio.h>
• #include<conio.h>
• #include<graphics.h>
• main()
• {
• int gd,gm,i,j;
int a[13][9] = {
• { 0, 0, 0, 0, 1, 0, 0, 0, 0},
• { 0, 0, 0, 1, 0, 1, 0, 0, 0},
• { 0, 0, 1, 0, 0, 0, 1, 0, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 1, 1, 1, 1, 1, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• { 0, 1, 0, 0, 0, 0, 0, 1, 0},
• };
• /* Initialise graphics mode */
• detectgraph(&gd,&gm);
• initgraph(&gd,&gm,"c:tcbgi");
• Lecture 2 7
for(i=0;i<13;i++)
{
for(j=0;j<9;j++)
{
putpixel(200+j,200+i,15*a[i][j]);
}
}
getch();
closegraph();
}

8. Bitmap Method
• This method is suitable for producing various
character.
• Font size of character can be increased by
increasing the size of array.
• The main draw back of this method is this
method produce aliased character.
30/9/2008 Lecture 2 8

9. 30/9/2008 Lecture 2 9
Starbust Method
1. In this method a fixed pattern of line is used to generate the
character.
2. In this method we use a combination of 24 bit line segment.
3. In 24 bit line segment code each bit represent a single line.
4. To highlight a line we put corresponding bit 1 in 24 bit line
segment code and 0 otherwise.

10. 30/9/2008 Lecture 2 10
Starbust Method
Disadvantages of starbust method
1. Here in this method 24 bit segment code is required to put in
memory for generating character. Hence extra memory is
required in this method.
2. Character quality is poor due to limited face.
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
0 1 0 1 1 1 0 1 0 1 0 1 1 0 0 0 1 1 0 1 0 1 0 1
24 bit line segment code

11. 30/9/2008 Lecture 2 11
THANK YOU!!