صفحه 1:
| Graphics
۱6
۱۱ Malaek
Assistant: M. Younesi
صفحه 2:
Overview
=" Display
Hardware
4 How are images
displayed?
صفحه 3:
Overview (Display
۱3 Dred sss) Ny
Random Scan Displays
Color CRT Monirors
Direct View Storage Tube
Flat panel Displays
۱ 71120
Devices
Stereoscopic and Virtual
Reality System
صفحه 4:
| Overview (Display
SURG EN MST
are often referred to
as Video Monitor
or Video Display
Unit (VDU).
صفحه 5:
Display Hardware
=" Video Display
Devices
=" The primary output
device in a graphics
system is a monitor.
صفحه 6:
Video Monitor
Cathode Ray
‘Tube
(CRT)
صفحه 7:
Electron Guns
Electron
Beams
Focusing Coils
Deflection Coils
Anode
Connection
Shadow Mask
Phosphor layer
Close-up of the
phosphor
coated inner
side of the
02
صفحه 8:
| Cathode Ray Tube (CRT)
Magnetic
Deflection Coils Phosphor-
Focusing ; _- Coated
System | Screen
Electron
Connector Electron Beam
Pins Gun
صفحه 9:
1۲۱6۲۲6۵۹۳ 1
= Light emitted by the
Phosphor fades very rapidly.
Refresh CRT: One way to keep
the phosphor glowing is to
redraw the picture repeatedly
by quickly directing the
electron beam back over the
same points.
صفحه 10:
Electron Gun
صفحه 11:
| Electron Gun
=" Heat is supplied to the
cathode by the filament.
صفحه 12:
| Electron Gun
=" The free electrons are
then accelerated
toward the phosphor
coating by a high
positive voltage.
صفحه 13:
on the inside of the CRT
envelope near the phosphor screen.
Magnetic
Deflection Coils
A positively charged
صفحه 14:
High Positive Voltage
= An accelerating anode .
Focusing
Cathode Anode
\
==
Heating اس - ۲ 1
Filament
/
Control Accelerating
Grid Anode
صفحه 15:
of the electron
beam is controlled by
setting voltage level on the
Focusing
Cathode Anode
Filament
Control Accelerating
Grid ‘
صفحه 16:
| Electron Gun
WT VI Cy am aCee relays
voltage on the control
grid simply decrease
تت ۶
electrons passing
through.
صفحه 17:
Focusing
System
صفحه 18:
| Focusing System
=" The focusing system is
needed to force the electron
beam to converge into a small
spot as it strikes the phosphor.
=" Electrostatic focusing is
commonly used in computer
graphics monitor.
صفحه 19:
With electrostatic focusing,
the electron beam passes
through a positively
charged metal cylinder that
صفحه 20:
| Focusing System
= Similar lens focusing
effects can be
accomplished with a
magnetic field set up by
a coil mounted around the
outside of the CRT
envelope.
صفحه 21:
| Focusing System
=" The distance that the electron
beam must travel to different
points on the screen varies
because the radius of curvature
for most CRTs is greater
than the distance from the
focusing system to the screen
center.
صفحه 22:
| Focusing System
= The electron beam will be
focused properly only at the
center of the screen.
= As the beam moves to the outer
edges of the screen, displayed
images become blurred.
=" Dynamically focusing lens
work based on beam position.
صفحه 23:
Deflection
"5
صفحه 24:
Deflection of the electron
beam can be controlled either
ل or with
The magnetic deflection coils
صفحه 25:
| Deflection Systems
=" Two pairs of coils are
used, with the coils in each
pair mounted on opposite
sides of the neck of the
CRT envelope.
صفحه 26:
One pair is mounted on the top and
bottom of the neck, and the other pair
is mounted on opposite sides of the
neck.
صفحه 27:
| Deflection Systems
=" Horizontal deflection is
accomplished with one pair of
coils, and vertical deflection
by the other pairs.
= The proper deflection amounts
are attained by adjusting the
لكف حاوف ار واف لال ةقلق
صفحه 28:
| Deflection Systems
=" Flectrostatic
deflection: Two pairs
of parallel plates are
mounted inside the
CRT envelope.
صفحه 29:
Deflection Systems
= One pair of plates is mounted
horizontally to control the vertical
deflection, and the other pair is
mounted vertically to control
صفحه 30:
ار
صفحه 31:
أخطن11! 01 5اممهك |
=" Spots of lights are
produces on the screen by
the transfer of the CRT
beam energy to the
phosphor.
= Part of the beam energy is
converted into heat energy.
صفحه 32:
| SOU Rae eg ol
=" The excited phosphor
electrons begin dropping
back to their stable ground
state, giving up their extra
energy as small quantums
of light energy.
صفحه 33:
| Persistence
" Persistence :The
۱۱:۱۱ ۹ A aXe)
emitted light from the
screen to decay to
one-tenth of its
011011131 ۰
صفحه 34:
The intensity is greatest
at the center of the spot,
and decrease with
Gaussian distribution out
to tj P spot.
صفحه 35:
Resolution (Spots of
Light)
=" Resolution: The
maximum number of
points that can be
displayed without
a)
Overlap
صفحه 36:
Resolution (Spots of
Light)
= Resolution of a CRT is dependent
on:
o The type of phosphor
° The intensity to be
1310112130
۳
deflectionisystemsn:: 1280 by 1024
صفحه 37:
Aspect Ratio
*" Aspect Ratio: This
numbers gives the ratio of
vertical points to
horizontal points
necessary to produce
equal length lines in both
directions on the screen.
صفحه 38:
Electron Guns
Electron
Beams
Focusing Coils
Deflection Coils
Anode
Connection
Shadow Mask
Phosphor layer
Close-up of the
phosphor
coated inner
side of the
electron
صفحه 39:
Cathode Ray Tube (CRT)
Anode Connection
Electron,
Der Beam
Electron
Gan.
صفحه 40:
Raster Scan
Displays
صفحه 41:
Raster Scan Displays
= Raster: A rectangular
array of points or dots
=" Pixel: One dot or picture
element of the raster
صفحه 42:
In a raster scan system, the
electron beam is swept
across the screen, one row at
صفحه 43:
| Raster Scan Displays
= As the electron beam
moves across each row,
the beam intensity is
turned on and off to
create a pattern of
illuminated spots.
صفحه 44:
Raster Scan Displays
= Picture definition is stored in a
memory area called the refresh
صفحه 45:
| Raster Scan Displays
" Refresh buffer or
frame buffer: This
memory area holds
the set of intensity
values for all the
screen points.
صفحه 46:
Stored intensity values then
retrieved from refresh buffer and
ji ” on the screen one row
صفحه 47:
| Raster Scan Displays
= Intensity range for pixel
positions depends on the
capability of the raster system.
= A black-and-white system:
each screen point is either on
or off, so only one bit per
pixel is needed to control the
intensity of screen positions.
صفحه 48:
| Raster Scan Displays
=" On a black-and-white
system with one bit per
pixel, the frame buffer is
called bitmap.
=" For system with multiple
bits per pixel, the frame
buffer is called pixmap.
صفحه 49:
| Raster Scan Displays
=" Sometimes, refresh
rates are described
in unit of cycles per
second, or Hertz
(HZ)
صفحه 50:
Raster Scan Displays
=" Refreshing on raster
scan displays is
carried out at the
rate 60 to 80 frame
per second.
صفحه 51:
: The
return to the left of the
screen, after refreshing
صفحه 52:
: At the end of
each frame (displayed in 1/80"
to 1/60" of a second) the
electron beam returns to the top
صفحه 53:
Interlacing
=" On some raster systems (TV),
each frame is displays in two
صع منفتا مععووم oleae
صفحه 54:
| Interlacing
=" On an older, 30 frame per-
second, noninterlaced display,
some flicker is noticeable.
= With interlacing, each of the
two passes can be accomplished
in 1/60 of a second.
An effective technique for
avoiding
صفحه 55:
| Raster image
=" The quality of a raster
image is determined by
the total number pixels
(resolution), and the
amount of information in
each pixel (color depth)
صفحه 56:
| Raster image
=" Raster graphics cannot be
scaled to a higher
resolution without loss of
2-0
صفحه 57:
Raster image
Brightness and color @ each x, y on
screen
صفحه 58:
Random Scan
Displays
صفحه 59:
| Random Scan Displays
= Random scan display is the use
of geometrical primitives such
as points, lines, curves, and
polygons, which are all based
upon mathematical equation.
=" Raster Scan is the
representation of images as a
collection of pixels (dots)
صفحه 60:
| Random Scan Displays
=" In a random scan display, a CRT
has the electron beam directed
only to the parts of the screen
where a picture is to be drawn.
= Random scan monitors draw a
picture one line at a time
(Vector display, Stroke -
writing or calligraphic
displays).
صفحه 61:
| Random Scan Displays
= The component lines of a
picture can be drawn and
(1۰
صفحه 62:
| Random Scan Displays
=" Refresh rate depends on the
number of lines to be
displayed.
= Picture definition is now stored
as a line-drawing commands an
area of memory referred to as
refresh display file (display
list).
صفحه 63:
| Random Scan Displays
=" To display a picture, the
system cycle through
the set of commands
in the display file,
drawing each
component line in turn.
صفحه 64:
Random scan displays are
designed to draw all the
component lines of a picture 30
صفحه 65:
Random scan displays are designed
for او
can not display realistic shaded
صفحه 66:
| Random Scan Displays
| ۳5
7646 [
صفحه 67:
Random scan displays have higher
resolution than raster systems.
Vector displays product smooth line
لا
1
Ideal Drawing
صفحه 68:
A raster system produces jagged
lines that are plotted as discrete
Filled primitives
صفحه 69:
| Random Scan Example
Data are describing a circle:
= the radius r
= The location of the center point
of the circle
= Stroke line style and color
= Fill style and color
صفحه 70:
Random Scan Example
(0۷۵۵۵06:
This minimal amount of information
translates to a much smaller file size.
(file size compared to large raster
images)
On zooming in, and it remains smooth
The parameters of objects are stored
and can be later modified
(transformation).
صفحه 71:
Color CRT
Monitors
صفحه 72:
| Color CRT Monitors
=" A CRT monitor displays
color pictures by using a
combination of
phosphors that emit
different COlor
۱۱
صفحه 73:
| Methods
1. Beam
Penetration
2. Shadow Mask
صفحه 74:
Beam Penetration
Method
صفحه 75:
| Beam Penetration Method
" Two layers of phosphor
09 -lacmoreyo1neel
onto the inside of the CRT
520۳991۰
= The display color depends on
haw far the electron beam
penetrates into the phosphor
تا
صفحه 76:
| Beam Penetration Method
=" The speed of the
electrons, and the
screen color at any
point, is controlled by
the beam
acceleration
voltage.
صفحه 77:
| Beam Penetration Method
The beam penetration method:
=" Used with random scan
monitors
= Only four colors are possible
(red, green, orange, and
داكت
= Quality of pictures is not as
good as with other methods.
صفحه 78:
Shadow Mask
Method
صفحه 79:
Shadow Mask Method
The color CRT has:
" Three color Phosphor
dots (red, green and blue) at
each point on the screen
۱۷ LTE
each controlling the display of
red, green and blue light.
صفحه 80:
| Shadow Mask Method
Delta Method:
صفحه 81:
صفحه 82:
Shadow Mask Method
The in-line method:
Phosphor
= /
5
۳
lJ
صفحه 83:
Shadow Mask Method
=" We obtain color
variations by varying
the intensity levels
of the three electron
۱91-4
صفحه 84:
Shadow Mask Method
Shadow mask methods
are:
= Used in raster scan system
(including color TV)
=" Designed as G>
monitors.
صفحه 85:
| Shadow Mask Method
=" High quality raster
graphics system have
24 bits per pixel in the
frame buffer (a full
color system or a true
color system)
صفحه 86:
Color Models
صفحه 87:
, G, and / represent the colors
produced by ۵/93
phosphors, respectively.
1,0,1
صفحه 88:
RGB color space
صفحه 89:
CMY (short for Cyan, Magenta,
, and key) isa
۴ M Color
0.0 0.0 x White
0.0
1.0
0.0
1.0
0.0
1.0
1.0
0.0
0.5
0.5
صفحه 90:
CMY Color Model
6 1 1
كار -١11- ©
Y ۱ ۲2
صفحه 91:
۳۹۲ Depth, Bit Depth
=" The number of discrete intensities
that the video card is capable of
generating for each color determines
the maximum number of colors that
can be displayed.
=" The number of memory bits required
to store color information (intensity
values for all three primary color
components) about a pixel is called
color depth or bit depth.
صفحه 92:
| 1ه Depth, Bit Depth
= A minimum of one memory bit
(color depth=1) is required to
store intensity value either 0 or 1
for every screen pixel.
= If there are n pixels in an image a
total of n bits memory used for
storing intensity values (in a pure
black & white image)
صفحه 93:
The block of memory which stores (or is
mapped with) intensity values for each
pixel (B& W image) is called a
1 bit
2۱۵8
Electron
Gun
صفحه 94:
Color or gray levels can be achieved
in the display using additional bit
‘green
COLOR: black red green blue yellow cyan magenta white
صفحه 95:
| N Bit Planes
=" The result for n bits per
pixel (color depth=n) is
a collection of n bit
planes (2" colors or gray
shades at every pixel)
صفحه 96:
For of information are
used, one for each of the red, blue and green
signals that make a pixel.
A byte can hold 256 different values and so 256
intensities setting are possible for each electron
gun which mean each primary color can have
256 in =24 bitplanes, 8 bits
per color gun.
0224 = 16,777,216
صفحه 97:
High Color
= For high Color two bytes of
information are used, to store the
intensity values for all three color.
This is done by dividing 16 bits into
5 bits for blue, 5 bits for red and 6
bits for green. This means 32(=2°)
intensities for blue, 32 (=2° for red,
and 64 (=2°) for green.
= Loss of visible image quality.
صفحه 98:
256 color mode
=" The PC uses only 8 bits, 2 bits for
blue and 3 each for green and red.
=" Most of the colors of a given
picture are not available.
= A palette or look-up table is
used here.
صفحه 99:
| Color Palette
= A palette is a separate memory block
(in addition to the 8 bit plane)
created 256 different colors.
=" Each color is defined using the
standard 3 byte color definition that
is used in true color.
= The intensity values for each of the
three primary color component can
be anything between 0 and 255 in
each of the table entries.
صفحه 100:
Color Palette
= The intensity values for each of the three
primary color component can be anything
between 0 and 255 in each of the table
Total number of colors
available is called color
palette.
صفحه 101:
Raster Scan
OCT Ken tt ey
صفحه 102:
In addition to the central processing
unit (CPU), a special processor,
called the or
, is used to
Peripheral ۱-2
devices
صفحه 103:
A fixed area of the system memory
is reserved for the frame buffer, and
the video controller is given direct
access to the frame buffer memory.
Peripheral
devices
صفحه 104:
location, and the
corresponding screen positions,
are referenced in
صفحه 105:
are then labeled
from at the top of the
screen to 0 at the bottom. Along
each scan line, screen pixel
صفحه 106:
| Video Controller
= Two registers are used to store the
coordinates of the screen pixels.
The Basic
refresh
operation of
the video
صفحه 107:
| Video Controller
Some of operations can be
performed by the Video
Controller:
=" Refreshing operation
= Transformation (Areas of the
screen can be enlarged, reduces,
or moved during the refresh
cycles)
صفحه 108:
Raster Scan
Display Processor
صفحه 109:
A raster syq@mpqeigigira separate
/
The purpose of the is to free the CPU
from the graphics chores.
صفحه 110:
DP
= A major task of the display
processor is Scan Conversion.
= Scan Conversion: is digitizing
a picture definition given in
an application program into a
set of pixel intensity values
for storage in the frame
buffer.( scan conversion straight line
segment, Character )
صفحه 111:
| ۱
= Generation various line styles
(dashed, dotted, or solid)
= Displaying color areas
=" Performing certain
اق 0
manipulation on display
objects.
صفحه 112:
Random Scan
OCT Ken tt ey
صفحه 113:
Random Scan System
=" Graphic commands are translated
by the graphics package into a
display file stored in the system
memory.
This file is then accessed by the
Lo “Serer
1 I
I. ff -
صفحه 114:
صفحه 115:
Flat Panel
Displays
صفحه 116:
| Flat Panel Displays
= Aclass of video devices that
have reduce volume and
weight compared to a CRT.
= A significant feature of flat
panel displays is that they
are thinner than CRTs.
صفحه 117:
| Flat Panel Displays
Current uses for flat panel
displays:
Small TV monitors
= Calculators
= Pocket video games
=" Laptop computers
= Advertisement boars in
elevators
صفحه 118:
Flat Panel Displays
1151 22261 75
=" Emissive or Emitters
Displays
= Non-emissive or Non-
emitters Displays
صفحه 119:
| Emissive (or Emitters)
" Emissiveldisplasconvert
electrical energy into light.
= Examples: Plasma panel,
thin-film electroluminescent
displays, Light-Emitting
Diodes (LED) and flat CRT.
صفحه 120:
Non-Emissive (or Non-
Emitters) Displays
Use optical effects to
convert sunlight or light
from some other source
into graphics pattern.
" Example: Liquid-Crystal
Device (LED)
صفحه 121:
Flat CRT
صفحه 122:
Flat CRT
=" Electron beams are accelerated
parallel to the screen, then
deflected 90° to the screen.
صفحه 123:
Plasma Panel
صفحه 124:
| Plasma Panel
= A layer of gas (usually
neon) is sandwiched
صفحه 125:
Plasma Panel
= By applying high voltage to a pair of
horizontal and vertical conductors, a
small section of the gas (tiny neon
bulb) at the intersection of the
conductors break down into glowing
صفحه 126:
Thin Film
Electroluminesce
11
صفحه 127:
۰۲۳ 16 و و جوونت و تون
plates is filled with a phosphor,
such as zinc sulfide doped with
صفحه 128:
Light Emitting
Diode (LED)
صفحه 129:
| Light Emitting Diode
2 (Pep is arranged to
form the pixel positions in the
display, and picture definition is
stored in a refresh buffer.
= Information is read from the
refreshed buffer and converted to
voltage levels that are applied to
the diodes to produce the light
patterns in the display.
صفحه 130:
Liquid Crystal
Displays (LCD)
صفحه 131:
| 11110 01521
= Used in 51214 151 925, such as
calculators, laptop computers.
= Produce a picture by passing
polarized light (from the
surrounding or from an internal
light source) through a liquid-
crystal material that can be aligned
to either block or transmit the
light.
صفحه 132:
| 11110 01521 5
5 . (LCD
=" Liquid SrA These
compounds have a
crystalline arrangement
of molecules, yet they
cat
Pe
صفحه 133:
Liquid Crystal Displays
Two glass ۳۱۲۳6, در h containing a
light polarizer at right angles to the
other plate, sandwich the liquid
crystal materials.
Rows of horizontal transparent
conductor & columns of vertical
On State
صفحه 134:
| 11110 01521 5
رز ۱۵۱ 0 ل الا يا ا
through the material is
twisted so that it will pass
through the opposite
polarizer.
= The light is then reflected
back t the viewer.
صفحه 135:
Nematic
Liquid Crystal
Transparent 9 ۷
Conductor
Polarizer
Transparent
Conductor
صفحه 136:
To Caeoiixel, we apply a
to the two intersecting
to align the
molecules so that the light is not
Off State
صفحه 137:
Liquid Crystal Displays
Polarizer Polarizer
م72
صفحه 138:
صفحه 139:
Exercises
= Direct View Storage
Tubes
= Stereoscopic and
Virtual Reality
Systems
