Computer Graphics By : Pcti Group

Computer Graphics By : Pcti Group

Presentation Title | March 25, 2017 | <document classification>
Session 1: The Coverage: Introduction Conceptual Framework Interactive and Passive Graphics. Presentation Title | March 25, 2017 | <document classification>

Computer Graphics Computer Graphics is the Intermediary between the Application Model[program] and display HARDWARE that effects an output transformation from the objects In the application model to view of the model. Presentation Title | March 25, 2017 | <document classification>

Conceptual framework for Interactive Graphics: Graphics System Application Model Program Display Device/PC Presentation Title | March 25, 2017 | <document classification>

Interactive Graphics: As per the framework, a computer receives input from interaction devices, and output images to a display device.The S/W has 3 components: 1.Application Program: It Creates,Stores, and retrieves from the third Component, which is Graphics System. 2.Graphics System: This is responsible for actually producing the picture from the detailed descriptions. 3.Display Hardware: The actual HARDWARE device. Presentation Title | March 25, 2017 | <document classification>

Passive Graphics A Computer Graphics Operation that transforms automatically and Without operator intervention. Presentation Title | March 25, 2017 | <document classification>

Usage of Computer Graphics:
User Interfaces Interactive plotting in business,Science and Technology. Office automation and E-Publishing. CAD and CAM application. Simulation. Art and Commerce. Process Control. Cartography. Presentation Title | March 25, 2017 | <document classification>

Display Devices: Refresh CRT. Random and Raster Scan Monitor. Color CRT Monitors. Direct View Storage Tubes(DVST). Flat Panel Displays. Light Emitting Diodes and LCD’s. Hard Copy Devices. Presentation Title | March 25, 2017 | <document classification>

Session -2 The Coverage: * Refresh CRT. * Deflection. MAGNETIC ELECTRONIC DEFLECTION Raster and Random Scan Displays. * Presentation Title | March 25, 2017 | <document classification>

Refresh CRT: Cathode Control Grid Focussing Anode Accelerating Anode Display Screen. Electron Beam Path. Presentation Title | March 25, 2017 | <document classification>

Electrostatic deflection of the electron beam in a CRT.
Phosphor Screen Focussing System Vertical Deflection Plates Base Connector pins Horizontal Deflection Plates Electron Beam Presentation Title | March 25, 2017 | <document classification>

Random Scan System A Random scan system draws the Component lines of an object in any order Specified. Presentation Title | March 25, 2017 | <document classification>

Raster Scan System A Raster Scan system displays an Object as a set of discrete points Across each scan lines. Presentation Title | March 25, 2017 | <document classification>

Interlacing In Some raster scan Systems(TV sets etc.) each frame is displayed into passes using an interlaced refresh procedure.In first pass, the beam sweeps across every other scan line from top to bottom.Then after the vertical retrace, the beam sweeps out the remaining scan lines. Interlacing of the scan lines allows us to see the entire screen displayed in one half of the time and used with SLOWER REFRESHING RATES. With Interlacing , each of the two passes can be accomplished in 1/60th of a second.which brings the refresh rates nearer to 60 frames/second. This is the effecting Technique for avoiding flicker. Presentation Title | March 25, 2017 | <document classification>

Session 3: The Coverage: Color CRT. Shadow Masking. DVST. LED. LCD. Presentation Title | March 25, 2017 | <document classification>

Color CRT Monitors A CRT Monitors displays color pictures by using a combination of phosphorus that emit different colored light. By this , a range of different color displays with CRT are the beam penetration method and shadow Masking. Beam penetration method has been used with a random scan monitors.Two layers of phosphor,red and green are coated onto the inside of the CRT SCREEN and the displayed Color depends on how far the electron beam penetrates into the phosphor layers. Its an inexpensive way to produce color in random scan monitors and qualities of pictures is not as Good as with other Methods. A Presentation Title | March 25, 2017 | <document classification>

Selection Of shadow Masking
Magnified Phosphor-Do Triangle screen green red blue Selection Of shadow Masking Electron Guns Presentation Title | March 25, 2017 | <document classification>

Direct -View Storage Tubes
An alternative method for maintaining a screen image is to store the picture the picture information inside the CRT instead of refreshing the screen. A direct View Storage Tube(DVST) stores the picture information as a charge distribution just behind the phosphor-coated screen.Two Electron guns are used in a DVST. One ,the primary gun, is used to store the picture pattern;the second,the flood gun,maintain the picture display. They Don’t display colors and that selected parts of a picture cannot be erased. To eliminate a picture,the entire screen must be erased and the modified picture redrawn. The erasing and redrawing process can take several seconds for a complex picture. Presentation Title | March 25, 2017 | <document classification>

Light Emitting Diodes A third type of emissive device is the Light Emitting Diode.A matrix Of diode is arranged to form the pixel positions in the display, and the Picture definitions is stored in a refresh buffer.As in scan line refreshing of a CRT, information is read from the Refresh Buffer and converted to voltage levels that are applied to the diodes to Produce the light patterns in the display. Presentation Title | March 25, 2017 | <document classification>

Liquid Crystal Display
Commonly used in small systems ,such as calculators and computers.These non emissive devices produce a picture by Passing polarized light from the surroundings or from an Internal light source through a liquid crystal material that can Be aligned to either block or transmit signals (light). Presentation Title | March 25, 2017 | <document classification>

Session 4: The Coverage: *Introduction of Scan conversion. *Scan about a point. *Scan about a line. Presentation Title | March 25, 2017 | <document classification>

Scan Conversion Introduction Scan Converting About a POINT. a LINE. a CIRCLE. an ELLIPSE. Side effects of Scan Conversion Presentation Title | March 25, 2017 | <document classification>

Introduction Many scan conversion algorithms are implemented in computer hardware or firmware. However a specific graphic algorithm can be implemented in software. The most common used graphics Objects are the line,the sector,arc,the ellipse,The rectangle and the polygon. * We will assume that all objects lie within the Boundaries of the display device coordinate system. Presentation Title | March 25, 2017 | <document classification>

Scan Converting a point
A mathematical point(x,y) where x and y are the real numbers within an image area, needs to be scan converted to a pixel at location(x’,y’) y y Pixel grid Pixel Grid 3.0 P3(2.8,1.9) P3(2.8,1.9) 2 2.0 P2(2.2,1.3) P2(2.2,1.3) 1.0 1 P1(1.7,0.8) P1(1.7,0.8) x x Pixel Coordinates 0.0 1.0 2.0 3.0 Pixel Coordinates 3 1 2 Scan Converting Point Presentation Title | March 25, 2017 | <document classification>

Scan Converting a Scan Lines
A straight line may Be defined by two endpoints and an equation.The two End Points are described by(x1,y1) and (x2,y2).The equation of the line is used to describe the x,y coordinates of all the points that lie between these two endpoints. y (X2,y2) Y X (X1,y1) x The Straight Line Presentation Title | March 25, 2017 | <document classification>

Session 5: The Coverage: *Introduction To Line Drawings: DDA Algorithm BRESENHAM’S Algorithm. Presentation Title | March 25, 2017 | <document classification>

Bresenham's Line Algorithm
Bresenham's line algorithms is a highly efficient method for scan -converting lines.It produces mathematically accurate results using only integer addition,subtraction and multiplication by 2,which can be done by simple arithmetic shift operation. Scan-Converted Points y Yi+1 T t Yi s True Line S P1 x Xi Xi+1 Presentation Title | March 25, 2017 | <document classification>

DDA line Algorithm DDA OR DIGITAL DIFFERENTIAL ANALYZER ALORITHM IS AN INCREMENTAL SCAN-CONVERSION METHOD.THIS APPROACH IS CHARACTERIZED BY PERFORMINGCALCULATIONS AT EACH STEP RESULTS FROM THE PRECEDING STEP. SUPPOSE at step I we have to calculated(Xi,Yi) to be point on the line.Since the next POINT on the line is (Xi+1,Yi+1) should satisfy delta y/delta x = m where delta Yi+1 –Yi and delta x = Xi+1 –Xi ,we have Yi+1 = Yi +m.delta X OR Xi+1 = Xi +delta/m The DDA algorithm is faster than the direct use of line equation since it calculates Point the line with out any floating –point manipulation. However, a floating point addition still needed in determining each successive point.Furthermore, cumulative error due to limited precision in the floating point representation. May cause calculated points to draft away from their true position when the line is Relatively long. Presentation Title | March 25, 2017 | <document classification>

Session 6: The Coverage: *Scan Conversion of a Circle *Defining a Circle. Presentation Title | March 25, 2017 | <document classification>

Scan Converting a Circle
A Circle is the Symmetrical Figure. Any Circle Generating algo take advantage of the circle’s Symmetry to plot eight points for each value that the algorithm calculates. Eight way symmetry is used by reflecting each calculated points around each 45 degree axis. y (-Y,X) 3 (Y,X) 2 5 4 (-X,Y) 3 4 1 (X,Y) 2 1 x 1 2 3 4 (-x,-y) 5 8 (x,-y) 6 7 (-y,-x) (y,-x) Presentation Title | March 25, 2017 | <document classification>

Defining a Circle y y P=(Xi P= 2 2 (r cos , r Sin r x r y rcos x x x rcos Circle defined with a second –egree Polynomial equation. Circle defined with trigonometric functions Presentation Title | March 25, 2017 | <document classification>

Session: 7 The Coverage: *Scan Conversion of Ellipse. *Side Effects. Presentation Title | March 25, 2017 | <document classification>

Scan -Converting an Ellipse
The ellipse , like the circle,shows Symmetry.In the case of an ellipse,how ever,Symmetry is four rather than eight-way. There are two Methods of mathematically Defining an ellipse. PLOYNOMIAL METHOD OF DEFINING AN ELLIPSE: The polynomial method of defining an ellipse is given by the (X-h) 2 (Y-k) 2 = 1 Where (h,k) ellipse center a= length of major axis. B= length of minor axis. 2 2 a b When the polynomial method is used to define an ellipse,the value of x is added From h to a. For each step of x,each value of y is found by evaluating the expression. Y = b 2 x - h + k 1 - 2 a This method is very efficient,However, because the squares of a and (x-h) must be Found. Then floating point division of (x - h) 2 By a And floating point Multiplication of the square root [1 –(x-h) ] By b. Presentation Title | March 25, 2017 | <document classification>

Side Effects of Scan Conversion 1.ALIASING 2.Overstrike Presentation Title | March 25, 2017 | <document classification>

Session: 8 The Coverage: Transformations. Transformation Types. Geometric Transformation. Presentation Title | March 25, 2017 | <document classification>

2D Graphics Transformation Introduction: The object of 2D Graphics Transformation is to describe there operations in mathematical form suitable for computer processing and how they are used to achieve the Ends of object manipulation and motion. Presentation Title | March 25, 2017 | <document classification>

Transformation Types: Geometric Transformation Coordinate transformation Composite Transformation Presentation Title | March 25, 2017 | <document classification>

Geometric Transformation p ‘ y Object y Object p x x Under This ,An Object in the plane can be considered as set of points.Every object Point p has Coordinates (X,Y) and so the object is the sum total of all of its Coordinate points. If the object is moved to a new Position, it can be regarded as New Object Obj’, all of whose coordinate point P’ can be obtained from the original P by the application of a geometric transformation. Presentation Title | March 25, 2017 | <document classification>

Session: 9 The Coverage: *Coordinate Transformation. *Composite Transformation. * Concatenation of matrices. Presentation Title | March 25, 2017 | <document classification>

Coordinate Transformation Y’ Y O’ X’ Y P(x,y)(x’,y’) X O We have two coordinate Systems in the plane.The First System is located at the Origin O and has coordinate axes XY .The Second Coordinate System is located at origin O’ and has Coordinate axes x’y’ .Now each point in the Plane has two coordinate descriptions (x,y) and (x’,y’),depending upon which Coordinate System is used.IT MEANS THE TRANSFORMATION ARISING FROM A TRANSFORMATION APPLIED TO THE FIRST SYSTEM X,Y ,WE CAN SAY THAT A COORDINATE TRANSFORMATION HAS BEEN APPLIED. Presentation Title | March 25, 2017 | <document classification>

Composite Transformation The More complex geometric and coordinate transformations can be built from the basic transformations by using the process of composition of functions. Here the basic transformation of rotation[displacement of objects Scaling and the reflection can be represented as matrix functions. Geometric Transformations Coordinate Transformations Cos Cos R = -Sin Sin R cos cos sin - sin S S S = X . S S = Y S 1 X X . S S Y X Y 1 S Y Presentation Title | March 25, 2017 | <document classification>

Concatenation Of Matrices The advantage of introducing a matrix from for translation is that we can now build complex transformation by multiply the basic matrix transformations.This process is sometimes called concatenation of matrices.We must be able to represent the basic transformations as 3*3 homogeneous coordinate matrices so as to be compatible with the matrix of translation. Presentation Title | March 25, 2017 | <document classification>

Session: 10 The Coverage: Viewing and clipping. Window to view port Mapping. Presentation Title | March 25, 2017 | <document classification>

2D Viewing & Clipping World coordinate System: Much Like what we see in real life through a small window on the wall or the viewfinder or camera, a computer generated image often depicts a partial view of a large scene.Objects are placed into the scene by modeling transformations to a master coordinate System called as WORLD COORDINATE SYSTEM. A rectangular window with its edge parallel the axes of the WCS is used to select the portion of the scene for which an image is to be generated. Workstation Window Workstation Viewport 1 Viewport 1 World Coordinate System Presentation Title | March 25, 2017 | <document classification>

Window To View port Mapping Objective: The Objective of window -to -viewport mapping is to convert the world coordinates(wx,wy) of arbitrary point to its corresponding normalized device coordinates(vx,vy). VIEWPORT WINDOW wy vy vy wy 1 vy wx wx vy Presentation Title | March 25, 2017 | <document classification>

Session: 11 The coverage: Cohen Sutherland algorithm. Introduction to Interactive Graphics. Presentation Title | March 25, 2017 | <document classification>

Cohen Sutherland Algorithm Under this, we divide the LINE CLIPPING PROCESS into two phases: 1.Identify those lines which intersects the clipping window and so need to be clipped and, 2.Performed the clipping. All lines fall into one of the following clipping categories: 1.Visible:Both endpoints of the line within window 2.Not Visible:The line definitely lies outside the window.This will occur if the line from(x1,y1)to(x2,y2)satisfies any one of the following four inequalities. X1,X2>Xmax y1,Y2>ymin X1,X2<Xmin Y1,Y2<Ymin 3.Clipping Candidate: The line is neither 1 or 2. Presentation Title | March 25, 2017 | <document classification>

Pictorial View: Coheb Sutherland Algorithm Presentation Title | March 25, 2017 | <document classification>

Interactive Graphics: There are commonly interactive graphics devices are as follows: 1.Key-Board. 2.TOUCH PANELS. 3.Light Pen. 4.Graphics Tablet. 5.Joystick. 6.Mouse. 8.Voice System. Presentation Title | March 25, 2017 | <document classification>

Session: 12 The Coverage: Interactive Graphics Techniques. * Introduction of GKS. Presentation Title | March 25, 2017 | <document classification>

Interactive Graphical Technique Several techniques are used to aid the effective construction of pictures. These are: Constraints. Grids. Gravity Field. Rubber Band Method. Sketching. Dragging. Inking and painting. Presentation Title | March 25, 2017 | <document classification>

Graphical Kernel System Introduction: GKS(GRAPHICS KERNEL SYSTEM) was developed in to need for a standardized method of developing program.It represents a standard graphics interface with consistent syntax. Furthermore,GKS was designed so that it may be bound by means of subroutines to most common prog.Languages such as ,C,FORTRAN77,PASCAL, and BASIC. Presentation Title | March 25, 2017 | <document classification>

Session: 13 The Coverage: GKS primitives. GKS AS programming Language. Presentation Title | March 25, 2017 | <document classification>

GKS primitive attributes The graphics kernel System is based on four basic primitives: POLYLINE POLYMARKER FILL AREA TEXT Presentation Title | March 25, 2017 | <document classification>

Primitive basics: Syntax: POLYLINE(n,x,y) POLIMARKER(N.X,Y) FILL AREA(N,X,Y) where n = number of data points. X= X array. Y = Y array. TEXT (X,Y,”String) Presentation Title | March 25, 2017 | <document classification>

Computer Graphics

SESSION - 1 Presentation Title | March 25, 2017 | <document classification>

Index Introduction of Computer and Graphic Introduction of Computer Graphic Area of Computer Graphic General Special Types of Computer Graphic Passive Graphics Interactive graphics View of Interactive Graphics L1-1 Presentation Title | March 25, 2017 | <document classification>

Introduction of Computer and Graphic
Hardware Software Graphics:- Images Animation Picture Movies and figures, e.t.c L1-2 Presentation Title | March 25, 2017 | <document classification>

Introduction of Computer Graphic
The Object which is lies between the different Coordinates. Computer Graphics is the Intermediary between the Application Model[program] and display HARDWARE that effects an output transformation from the objects In the application model to view of the model. L1-3 Presentation Title | March 25, 2017 | <document classification>

Area of Computer Graphic
General Special L1-4 Presentation Title | March 25, 2017 | <document classification>

General Industry Medical Business Government Education and training Entertainment Defense Home Agriculture L1-5 Presentation Title | March 25, 2017 | <document classification>

Special Mathematical Ele. Industry Statistical Finance Government Defense Art and Design L1-6 Presentation Title | March 25, 2017 | <document classification>

Types of Computer Graphic
Passive Graphic Interactive Graphic L1-7 Presentation Title | March 25, 2017 | <document classification>

Passive Graphics A Computer Graphics Operation that transforms automatically and Without operator intervention. L1-8 Presentation Title | March 25, 2017 | <document classification>

Interactive Graphics: As per the framework, a computer receives input from interaction devices, and output images to a display device. L1-9 Presentation Title | March 25, 2017 | <document classification>

The S/W has 3 components: Application Program: It Creates, Stores, and retrieves the input. Application Model: It is a combination of object, data and relationship. Graphics System: This is responsible for actually producing the picture from the detailed descriptions. L1-1 0 Presentation Title | March 25, 2017 | <document classification>

Conceptual framework for Interactive Graphics: Graphics System Application Model Program Display Device/PC L1-11 Presentation Title | March 25, 2017 | <document classification>

View of Interactive Graphics
Geometric Graphic: - Explicit Declaration Select Criteria for insertion. NonGeometric Graphics: - Implicit Declaration Simple way of Insertion. L1-12 Presentation Title | March 25, 2017 | <document classification>

Summary L1-13 Presentation Title | March 25, 2017 | <document classification>

Introduction of Computer and Graphic Introduction of Computer Graphic Area of Computer Graphic General Special Types of Computer Graphic Passive Graphic Interactive graphic Application Model Application programming Computer Graphic View of Interactive Graphic L1-14 Presentation Title | March 25, 2017 | <document classification>

Questions L1-15 Presentation Title | March 25, 2017 | <document classification>

Question 1. What do you mean by Computer Graphics? State its classification and outline the differences among these along with their application areas. L1-16 Presentation Title | March 25, 2017 | <document classification>

Question 2. What are the various types of Computer Graphics? And where they are used? L1-17 Presentation Title | March 25, 2017 | <document classification>

Question 3. Explain the Framework of Interactive Graphics? L1-18 Presentation Title | March 25, 2017 | <document classification>

SESSION - 2 Presentation Title | March 25, 2017 | <document classification>

Index Advantages of Computer Graphics. Usage of Computer Graphics. Overview of Display Devices. Monitors Tubes CRT’s Random and Raster Scan Presentation Title | March 25, 2017 | <document classification>

Advantages of Interactive Graphics
Most Efficient way of communication Expressive way of presentation Interactive C.G Presentation Title | March 25, 2017 | <document classification>

Dynamic way of Picturing and fast processing. Update Dynamically High quality Presentation Title | March 25, 2017 | <document classification>

Usage of Computer Graphics:
User Interfaces Interactive plotting in business,Science and Technology. Office automation and E-Publishing. Computer-aided and Design Presentation Title | March 25, 2017 | <document classification>

Simulation and animation for scientific visualization and entertainment. Art and Commerce. Process Control. Cartography. Presentation Title | March 25, 2017 | <document classification>

Overview of Display Devices.
Monitors Tubes Printers Presentation Title | March 25, 2017 | <document classification>

Monitors Tubes Refresh CRT. Random and Raster Scan Monitor. Color CRT Monitors. Presentation Title | March 25, 2017 | <document classification>

Tubes Refresh CRT: - The Primary Device in a graphic system is a video monitor. The operation of most video monitors is based on the standard cathode-ray tube (CRT) design, but several other technologies exist and solid-state monitors may eventually predominate. Presentation Title | March 25, 2017 | <document classification>

Refresh CRT: Figure: Basic Design of a magnetic-deflection CRT The phosphor then emits a small spot of light at each position contacted by the electron beam. Because the light emitted by the phosphor fades very rapidly, some method is needed for maintaining the screen picture. Presentation Title | March 25, 2017 | <document classification>

Operation of an electron gun with an acceleration anode
The focusing system in a CRT is needed to force the electron beam to converge into a small spot as it strikes the phosphor. Presentation Title | March 25, 2017 | <document classification>

Electrostatic deflection of the electron beam in a CRT
Figure 2.4: Electrostatic deflection of the electron beam in a CRT Spots of light are produced on the screen by the transfer of the CRT beam energy to the phosphor. Presentation Title | March 25, 2017 | <document classification>

Intensity distribution of phosphor spot on a CRT screen
Different kinds of phosphors are available Besides color, a major difference between phosphors is their persistence: how long they continue to emit light (excited electrons) Persistence is defined as the time it takes the emitted light from the screen to decay to one-tenth of its original intensity. Presentation Title | March 25, 2017 | <document classification>

the intensity distribution of a spot on the screen. The intensity is greatest at the center of the spot, and decreases with a Gaussian distribution out to the edges of the spot. This distribution corresponds to the cross-sectional electron density distribution of the CRT beam. Another property of video monitors is aspect ratio. The ratio of vertical points to horizontal points necessary to produce equal-length lines in both directions on the screen. An aspect ratio of 3/4 means that a vertical line plotted with three points has the same length as a horizontal line plotted with four points. Presentation Title | March 25, 2017 | <document classification>

Random-Scan When operated as a random-scan display unit, 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 and for this reason are also referred to as Vector Display. Presentation Title | March 25, 2017 | <document classification>

Architecture of Random Scan System
CPU System Memory Display Processor Monitor System Bus I/O DEVICES Presentation Title | March 25, 2017 | <document classification>

Raster Scan System 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.Picture definition is stored in a memory area called the refresh buffer or frame buffer. This memory area holds the set of intensity values for all the screen points. Presentation Title | March 25, 2017 | <document classification>

Architecture of Raster Scan System
Display Processor Memory System Memory Video Controller Monitor Display Processor System Memory CPU System Bus I/O DEVICES Presentation Title | March 25, 2017 | <document classification>

Random-Scan and Raster-Scan
Electron Beam directed only to the parts of the screen where a Picture is drawn. 60 Frames Per Second A pen plotter operates in a similar way. Example: Hard-Copy Device. Raster-Scan: Based Upon Television technology Electron beam is swept across the Screen, one row at a time from top to bottom. Each Pixel is Plotted into the Pixel. Example: Printer Presentation Title | March 25, 2017 | <document classification>

Interlacing In Some raster scan Systems(TV sets etc.) each frame is displayed into passes using an interlaced refresh procedure.In first pass, the beam sweeps across every other scan line from top to bottom.Then after the vertical retrace, the beam sweeps out the remaining scan lines. Interlacing of the scan lines allows us to see the entire screen displayed in one half of the time and used with SLOWER REFRESHING RATES. With Interlacing , each of the two passes can beaccomplished in 1/60th of a second.which brings the refresh rates nearer to 60 frames/second. This is the effecting Technique for avoiding flicker. Presentation Title | March 25, 2017 | <document classification>

Questions Presentation Title | March 25, 2017 | <document classification>

Question 1. What are Raster-Scan Graphic Systems? How does Raster-Display Processor play an important role in its functioning? Explain. Presentation Title | March 25, 2017 | <document classification>

Question 2. Write a short note on i) Random scan monitors ii) Raster scan monitors Presentation Title | March 25, 2017 | <document classification>

Question 3. Explain the working of CRT ? What are the primary components of CRT? What are the needs of CRT refreshing? Presentation Title | March 25, 2017 | <document classification>

Lecture - 3

Index Color CRT. Shadow CRT DVST(Direct-View Storage Tubes) Shadow Masking Flat Panel Display LED(Light Emitting Diode) LCD Presentation Title | March 25, 2017 | <document classification>

Color CRT Monitors A CRT Monitors displays color pictures by using a combination of phosphorus that emit different colored light. A range of different color displays with CRT are the beam penetration method and shadow Masking. Beam penetration method has been used with a random scan monitors. A Presentation Title | March 25, 2017 | <document classification>

Two layers of phosphor: Red Green Its an inexpensive way to produce color in random scan monitors and qualities of pictures is not as Good as with other Methods. Presentation Title | March 25, 2017 | <document classification>

Shadow Masking Presentation Title | March 25, 2017 | <document classification>

the intensity levels of the three electron beams. Red Green The color we see depends on the amount of excitation of the red, green, and blue phosphors. A white (or gray) area is the result of activating all three dots with equal intensity. Yellow is produced with the green and red dots only, magenta is produced with the blue and red dots, and cyan shows up when blue and green are activated equally. Presentation Title | March 25, 2017 | <document classification>

Color graphics systems can be designed to be used with several types of CRT display devices. inexpensive home-computer systems and video games Example: - TV set and an RF (radio-frequency) modulator. These display devices still require that the picture information be combined. High-quality raster-graphics systems have 24 bits per pixel in the frame buffer, allowing 256 voltage settings for each electron gun and nearly 17 million color choices for each pixel. Presentation Title | March 25, 2017 | <document classification>

Direct -View Storage Tubes
Maintaining a screen image is to store the picture the picture information inside the CRT. Picture information as a charge distribution just behind the phosphor-coated screen. Two Electron guns are used in a DVST: - Primary gun is used to store the picture pattern. The flood gun,maintain the picture display. Presentation Title | March 25, 2017 | <document classification>

They Don’t display colors and that selected parts of a picture cannot be erased. To eliminate a picture,the entire screen must be erased and the modified picture redrawn. Presentation Title | March 25, 2017 | <document classification>

Flat-Panel Displays A class of video devices that have reduced volume, weight, and power requirements compared to a CRT. Feature of flat-panel displays: - thinner than CRTs Example: - pocket notepads and small TV monitors, calculators, pocket video games, laptop computers, advertisement boards in elevators, etc. We can separate flat-panel displays into two categories: emissive displays: - devices that convert electrical energy into light. Non emissive displays: -Use optical effects to convert sunlight or light from some other source into graphics patterns. Example: liquid-crystal device. Presentation Title | March 25, 2017 | <document classification>

Basic design of a plasma-panel display device
Presentation Title | March 25, 2017 | <document classification>

Basic design Presentation Title | March 25, 2017 | <document classification>

Light-emitting Diode (LED)
A matrix of diodes is arranged to form the pixel positions in the display, and picture definition is stored in a refresh buffer. The refresh buffer and converted to voltage levels that are applied to the diodes to produce the light patterns in the display. Presentation Title | March 25, 2017 | <document classification>

Liquid-crystal Displays (LCD’s)
Liquid-crystal displays (LCDs) are commonly used in small systems, such ' as calculators, portable, laptop computers. These non-emissive devices produce a picture by passing polarized light from the surroundings or from an internal light source through a liquid-crystal material that can be aligned to either block or transmit the light. Presentation Title | March 25, 2017 | <document classification>

A hand calculator with an LCD screen
Presentation Title | March 25, 2017 | <document classification>

The light-twisting, shutter effect used in the design of most liquid-crystal display devices Presentation Title | March 25, 2017 | <document classification>

Question Presentation Title | March 25, 2017 | <document classification>

Question -1 Give the advantages and disadvantages of hard copy displays, DVST displays, vector refresh displays and raster displays. Suggest an application area for which each class of device is best suited. Presentation Title | March 25, 2017 | <document classification>

Question – 2 Why is the electron beam allowed to overscan? Also discuss about the technique which involves splitting a raster-scan pattern into separate patterns. Presentation Title | March 25, 2017 | <document classification>

Question – 3 What are Raster-Scan Graphic Systems? How does Raster-Display Processor play an important role in its functioning? Explain. Presentation Title | March 25, 2017 | <document classification>

Question - Differentiate the working principles of LCD and Plasma Panel Displays. Presentation Title | March 25, 2017 | <document classification>

SESSION – 4

INDEX Hard Copy Device Laser Printer Ink – Jet Printer. Electrostatic device Place Pen Plotter. Presentation Title | March 25, 2017 | <document classification>

Hard Copy Device We can obtain hard-copy output for our images in several formats. To put images on film, we can simply photograph a scene displayed on a video monitor. The quality of the pictures obtained from a device depends on dot size and the number of dots per inch, or lines per inch, that can be displayed. A line printer is an example of an impact device, with the typefaces mounted on bands, chains, drums, or wheels. Presentation Title | March 25, 2017 | <document classification>

A picture generated on a dot-matrix printer showing how the density of the dot patterns can be varied to produced light and dark areas Presentation Title | March 25, 2017 | <document classification>

Laser Printer Laser beam creates a charge distribution on a rotating drum coated with a photoelectric material. Toner is applied to the drum and then transferred to paper. examples of desktop laser printers with a resolution of 360 dots per inch. Presentation Title | March 25, 2017 | <document classification>

INK – JET METHOD Ink-jet methods produce output by squirting ink in horizontal rows across a roll of paper wrapped on a drum. The electrically charged ink stream is deflected by an electric field to produce dot-matrix patterns. A desktop ink-let plotter with a resolution of 360 dots per inch. Presentation Title | March 25, 2017 | <document classification>

Electrostatic Device Places
An electrostatic device places- a negative charge on the paper, one complete row at a time along the length of the paper. Then the paper is exposed to a toner The toner is positively charged and so is attracted to the negatively charged areas, where it adheres to produce the specified output. A color electrostatic printer/plotter is shown in Figure Electro thermal methods use heat in a dot- matrix print head to output patterns on heat-sensitive paper. Presentation Title | March 25, 2017 | <document classification>

Pen Plotter A pen plotter has one or more pens mounted on a carriage, or crossbar, that spans a sheet of paper. Pens with varying colors and widths are used to produce a variety of shadings and line styles. Wet-ink, ball-point, and felt-tip pens are all possible choices for use with a pen plotter. Plotter paper can lie flat or be rolled onto a drum or belt. Crossbars can be either moveable or stationary, while the pen moves back and forth along the bar. Presentation Title | March 25, 2017 | <document classification>

Question -1 Write a short note on hard copy devices. Presentation Title | March 25, 2017 | <document classification>

Question -2 Discuss the detailed of DVST. Presentation Title | March 25, 2017 | <document classification>

SESSION - 5

INDEX Introduction Scan-converting a Point Scan-converting a Straigh Line Presentation Title | March 25, 2017 | <document classification>

INTRODUCTION Converting binary values stored. pixel-on pixel-off information. More Complex graphics objects Points Lines Circles Ellipses. Presentation Title | March 25, 2017 | <document classification>

Human users with fast Memory-efficient routines The process of representing continuous graphics objects as a collection of discrete pixels is called scan conversion Many scan-conversion algorithms are implemented in computer hardware or firmware. The most commonly used graphics objects are line, the sector, the arc, the ellipse, the rectangle and the polygon. Presentation Title | March 25, 2017 | <document classification>

Scan - Converting a Point
A mathematical point (x, y) where x and y are real numbers. x’ = Floor(x) and y’ = Floor(y), x’ < x < x’ + 1 and y’ < y < y’ + 1 are mapped to pixel (x’ y’). Here we scan convert (x, y) x’ = Floor(x + 0.5) and y’ = Floor(y + 0.5). Presentation Title | March 25, 2017 | <document classification>

Scan - Converting a Straight Line
The two endpoints are described by (x1, y1) and (x2, y2). Using the equation of a straight line, y = mx + b where m = Δy/Δx and b = the y intercept, Interactive graphics is a graphics system in which the user dynamically controls the presentation of graphics models. Presentation Title | March 25, 2017 | <document classification>

THE LINE Presentation Title | March 25, 2017 | <document classification>

Direct Use Of Line Equation
First scan-convert P1 and P2 to pixel coordinates (x’1, y’1) and (x’2, y’2), respectively; then set m = (y’2 - y’1) / (x’2 - x’1) and b = y’1 –mx’1. If |m| > 1, then for every integer value of y between and excluding y’1 and y’2 calculate the corresponding value of x using the equation and scan-convert (x, y). While this approach is mathematically sound, it involves floating-point computation Presentation Title | March 25, 2017 | <document classification>

Example Presentation Title | March 25, 2017 | <document classification>

E1. The endpoints of a given line are (0, 0) and (6, 18). Compute each value of y as x steps from 0 to 6 and plot the results. An equation for the line was not given. (y = mx + b) y = 3x +b: 0 = 3(0) + b. Therefore, b = 0, so the equation for the line is y = 3x Presentation Title | March 25, 2017 | <document classification>

E2. What steps are required to plot a line whose slope is between 0o and 45o using the slope-intercept equation 1. Compute dx: dx = x2 - x1. 2. Compute dy: dy = y2 – y1. 3. Compute m: m = dy/dx. 4. Compute b: b = y1 – m  x1. Presentation Title | March 25, 2017 | <document classification>

5. Set (x, y) equal to the lower left-hand endpoint and set xend equal to the largest value of x. If dx < 0, then x = x2, y = y2, and xend = x1. If dx > 0, then x = x1, y = y1, and xend = x2. 6. Test to determine whether the entire line has been drawn. If x > xend, stop. 7. Plot a point at the current (x, y) coordinates. Presentation Title | March 25, 2017 | <document classification>

8. Increment x: x = x + 1. 9. Compute the next value of y from the equation y = mx + b. 10. Go to step 6. Presentation Title | March 25, 2017 | <document classification>

Use pseudo-code to describe the steps that are required to plot a line whose slope is between 45o and –45o (i.e., [m] > 1) using the slope-intercept equation. Presume y1 < y2 for the two endpoints (x1 , y1) and (x2, y2): int x = x1, y = y1; float xf, m = (y2 – y1)/(x2 - x1), b = y1 = mx1; Set Pixel (x, y); while (y < y2); y++; xf = (y – b)/m; x = Floor(xf + 0.5); Set Pixel (x, y);} Presentation Title | March 25, 2017 | <document classification>

Question -1 How is the point displayed on the graphics scale? Presentation Title | March 25, 2017 | <document classification>

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