ページ3:

Random Scan Display
>> It use an electron beam which operates like a pencil to create a live image on CRT screen.
⇒ The picture is constructed out a of a sequence of straight-line segments. __
⇒ Each line segment is drawn on the screen by directing the beam to move from one point on the
screen to the next, where it key coordinates defines each paint.
>> After drawing the picture, the system cycles bach to the first line and again all the line
of the image.
Random Scan monitors are also known
as Vector displays or store-writing
display or calligraphic displays.
vector, stroke-writing, calligraphic
Advantage
⇒ A CRT has the electron beam directed
only to the pouts of the screen where on
image is to be drawn.
=> Produce smooth line drawings
=> High Resolation
Disadvantage
=> Random Scan monitors cannot display
realistic shades scenes.

ページ4:

Raster Scan Display
In a Raster scan sys,
from top to bottom.
the electron beam is swept across the screen, one row at a time
>>As the electron beam moves across each row, the beam intensity is turned on a off to create
a pattern of illuminated spots.
>>Picture definition is stored in memory are a called the refresh Butter or ficave Butter
=> This memory area holds the set of intensity values for all the screen point.
Stored intensity values are then retrieved from the refresh buffer and "Painted " on the
screen one row cscanline) at a time like.
Like,
a time like,
horizontal
retrace
Types of scanning or
Scan line
vertical
retrace
⇒ Each screen paint is refered as a pixel
(picture element) At end of each line,
the electron beam return to the left
side of the screen to begin displaying
the next scan line.
traveling of beam in Roster scan
I. Interlaced scanning
I. Non Interlaced scanning
①Interlaced Scanning: Each horizontal line of the screen is traced from top-botion,
Due to which fading of display of object may occur. This problem can be solved by
non-interlaced scanning. In this first of all odd no. lines one traced or visited
by an electron beam, then in the next circle, Even no. of line are located.
② Non-interlaced Scanning: Non - interlaced display refresh rate of so frames per
second used. But it gives flickers. For interlaced display refresh rate of be frames
per second is used.
Advantages
1. Realistic image
2. Million Different colors to be generated
3. Shadow Screen are possible.
30
Disadvantages
1. Low Resolution
2. Expensive

ページ5:

Difference Between Random & Roster Scan Display
Random scan
>> It has high resolution
It is more expensive
Raster Scan
=> Its resolution is low
⇒ It is less expensive
⇒ Any modification if needed is easy ⇒ Modification is tough
⇒ Solid pattern is tough to fill
Refresh rate depends on resolution.
⇒ only scree with view on area is
dis played
=> Beam penetration technology
come under it
It does not use interlacing method
⇒ Solid pattem is easy
=
to fill
Refresh rate does not depend on
the picture
whole screen is scanned
⇒ shadow mark technology came
under this
>> It use interlacing
⇒ It is restricted to line drawing applications = It is suitable for realistic display

ページ6:

Direct View Storage Tubes
"
A
DVST terminals also use the random scan approach to generate the
image on the CRT Screen. The term "storage tube" refers to the ability of
the screen to retain the image which has been projected against it, they avoid
the need to rewrite the image constantly.
Function of Gun
Two guns are used in OYST
1. Primary Gun : It is used to store the picture pattern
2. Flood Gun or Secondary gun: It is to maintain picture display
Aboodgun Secondary gun
Flood Electrons
← Screen
strage arid
Primary
gun
Jocusing &
deflection sys
Advantages
1. No refreshing is needed
2. High resolution
3. cast is very less
Collecto
Disadvantages
1. It is not porsible to erase the selected part
of a picture
2. It is not suitable for dynamic graphic
applications
3. It a part of picture is to modify, then
time is consumed.

ページ7:

Flat Panel Display
It refers to a class of video devices that have reduced volume, weight and
requirement compare to CRT.
Ex. Small TV monitor, calculator, pocket video games,
laptop computers and advertisement board in elevator.
@ Emissive Display: The Devices that convert electrical
energy
into light.
Ex. Plasma Panel, thin film electroluminescent display & LED
Flat Panel Display
Emissive Display
Ex. Plasma Panels, LED
• Non-Emissive Display
Ex. LCD
power
Non-Emissive Display: It use optical effect to covert sunlight or light from some other
source into graphic patterns
Ex. LCD
Input devices
- Import devices are hardware that is use to transfers imput to the competer.
The data can be in the form of text, graphics, sound.
-Output device display data from memory of the computer output can be text,
number data, line, polygon & other objects.
processed
imput
CPU
"data output
-
input
devices
Memory
devices
Resent of
Processing in
humum acceptable
form
Keyboard 101 keys
Mouse
⇒pt device
Trackball pt device) 20
Spacebar six direction
input devices
soy stack
four direction
voice recognition
Image scanner
Touch screen
Digitizer
Light Pen
output accept data from computer &
translates them into from understand by user.
Printers, Plotters

ページ8:

DDA (Digital Differential Analyse)
⇒ It is a scam conversation method for drawing lines.
⇒ incremental approach
Difference in pixel point is to be analyzed
DDA line Drawing Algorithm
DOA stands for digital differential analyzer
=> Straight line equation is y = mx+b
if the line has two end point ACX., Y₁) & BCX 2 Y ₂)
slope of line is m₂ Ye-y₁
X2-X1
.. m³
DDA Algorithm based on calculation of values AX, AY
pixels
A(X,Y₁)
Blz. Ye)
y=mx+b
A dy
AX dy
civ
(i) y ³ mx+b
·Y2-1 (X-X)
y-y," Yz-Y
X-X
caseci): If mc1
A+ X, +1
case liio: If m>
X = X₁₂+1
A
Yn 'y₁+m
me
Yn '99 +1
else decreased
AX
joy
DY=MAX.
DX - DY/M - @
Given line have a slope +ve or -ve
If +ve, the AX & AY value are increased
case ciii): If m 1
Xnx₁+9
Y₁ = y₁+1

ページ9:

step 2: calculate dxx₂-x,
dy = 92-99
step 4: cnbulate sx = dy, Ay + dy
DDA Algorithm
step 1: Accept stort & End point cardinates (X,, Y₁) & (X, Y₂)
step 3: If aks cdx) > abs (dy) // m<1
then k = abs cdx) dx > dy
else k• abscdy) m<1°
(2,5)
19
dy
2
k
case ci): If m<1
Xn *X₁+1
case cii): If m>i
Xnx₁+ 1
case cli): It
m = i
Xn 2Xq +1
m
น
In = 4₁+1
Yn cy₁tm
9₁ = y₁ + 1
steps: Initialize x*x₁, y = ½₁
step 6: Display pixel (x,y)
Step 7: X+X+AX, yey+ay
Advantage
step 8: Display pixel round (c), round (y)
Stepa: Repeat s, & 8, `k' times
It is a faster method when compared to direct use of line equation.
This method does not use multiplication theorem
=> It allows us to detect the the change in value x and y, so plotting of same point.
twice is not possible
X = X+AX
This method gives overflow indication when a point is repositioned
⇒It is an easy method because each step involves just hers additions
Disadvantage
⇒ It involves floating point additions rounding off is done. Accummulation of round off
error cause error.
⇒ It is more suitable for generating line using the softuhase. But it is less
suited for hardware implementation.

ページ10:

Digital Differential Analyzes &DDA}
Is an incremental scan conversion method of line drawing
DDA attempt to generates the points between starting & Ending cordidantes
Algorithm head start & End coordinates
↓
(No, Yo)
step₁ calculate AR, DY & M
AN = N
Ay = yn - Yo
L
(Mn, Yn)
Mz Ay
0
step 2 find no. of paints in between
stand 2 ending coordinates
steps current point up, p²), next paint cxpm, 4p+)
find the rest point by following 3 cases.
if cabs cow >abs CAY))
lenght = k = abs (AK)
else habs cay)
(1494049)
caseci)
Case (ii)
Case di
• Myn
If M<I
If M20
If MyI
(xpyp)
Mo+1 = (1+1)
My+1(9+)
Np + = 1/1 + Mp
>
YpH (M+yp)
Yp+ (1+yp)
Yp+1 39+yp
Example
.
case y repeat step 3 until end point reached
①ANNn + No 28-5=3
ร
calalate no. of point @ As M>1 case ® is
Ay gn-Yo 12-6 = 6
IDM) <lay1=3<6
statisfied
M > AY
2
6
lenght k = Ay = 6
Xp+1 = (1/141 + kp)
An
22
3
Yp + q = (1+ Yp)
Draw the line between (5,S) & (10,9) using DDA algorithm
dxx₁₂-x₁ = 10-5 = 5
dx>dy | dn<dy
kodon
1-dy
iteration (i) plot croundx,y) (R+Ax y+Ay
dr
M...
b
dy=Y₂- Y₁ =
= 1-5 24
dx> dy s>4
0
(5,5)
1
(6,6)
6+17 5.810.866
k=dn=5
2
(7,7)
74168
(8,7)
(1,1)
1974+0.88.2
111 10 8.2+0.89
(10,9) 10+1 11 9+0.89.8
Ay, du
ง
2
10.8
5+1-6 5+0.805.8
6.6+0.8-74

ページ11:

Bresenham's line Algorithm
It determines the pts of an n-dimensional resta that should be selected
in order to form a close approximation to a straight line between 2 points
ACX, Y) BC X₂, Y₂)
Efficient => It only integer add, sub 2 multiple
The operations performed rapidly so next line com be generated quickly
Algorithm start cordinates (Xo Yo)
Case
End cordinates (Yn)
Pla+9 = Po +24y
2
If P<0 = Mar M4/11
case②
>
4+1 = Sh
If Ru >>> Phin' Ph + 2AY-2Ak
2 Me+1
NhH
Yhi & Yuta
Dave repeat
until End point is reached
Step1 calculate An&sy
ON = No
Dy = yn - Yo
Step2 calculate decision parameter
Pk = 2AY-Ax
It is used to find exact
point to draw live.
steps suppose current point (Xu, Yu),
next point (Xan, Yum) find next
paint depending on value of decision
paramater Pk = 2sy-on
>

ページ12:

Bresenham's line Algorithm
step 1: Lot start 2 End point (X,,Y,) & (X₂, Ye)
step 2: Finding decision panameter valu
di = 2dy-dx
dx = x 2 - x ₁
dy = y₂- Y₁
step 3: If di >0
1 2dx
di+t di+zdy + sdbe Zabove treen line}
Xnx₁+1
2
Yn y₁ +1
step 4: If di co
Advantage
plotted pts.
di +1 ditzdy
=
X-X1
Xy = y₁
{ below true line}
=>
⇒ It involve integer arithmetic, very simple
=> It avoids the generation of duplicate pts.
- It can be implemented using hardware
>>It is faster
=>
Disagreement
meant for basic line drawing only

ページ13:

20 Transformation => changing of an object after creation. (interm of position
different types of transformation
Translation
scaling
@Rejection
⑥Shearing
or size)
Photating
=> If will shift the object from one position to other position
=>To translate a point frown coordinate position agy to another
(x,y) we add algebrically the translation distances Tn & Ty to
Leshift rector
digital mordinaters x, x + Tn Yq *Y + Ty
Rotation It is a process of changing the angle of the object
Rotation can be dochnise or anticlockwise