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An ISO 9001:2008 Certified Organization PCTI Group Computer Graphics By : Pcti Group.

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Presentation on theme: "An ISO 9001:2008 Certified Organization PCTI Group Computer Graphics By : Pcti Group."— Presentation transcript:

1 An ISO 9001:2008 Certified Organization PCTI Group Computer Graphics By : Pcti Group

2 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 2 Session 1: The Coverage: Introduction Conceptual Framework Interactive and Passive Graphics.

3 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 3 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.

4 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 4 Conceptual framework for Interactive Graphics: Graphics System Application Model Application Program Display Device/PC

5 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 5 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.

6 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 6 Passive Graphics A Computer Graphics Operation that transforms automatically and Without operator intervention.

7 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 7 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. Usage of Computer Graphics:

8 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 8 Display Devices: Refresh CRT. Random and Raster Scan Monitor. Color CRT Monitors. Direct View Storage Tubes(DVST). Flat Panel Displays. Light Emitting Diodes and LCDs. Hard Copy Devices.

9 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 9 The Coverage: * Refresh CRT. * Deflection. MAGNETIC ELECTRONIC DEFLECTION * Raster and Random Scan Displays. Session -2

10 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 10 Cathode Control Grid Focussing Anode Accelerating Anode Display Screen. Electron Beam Path. Refresh CRT:

11 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 11 Base Connector pins Focussing System Horizontal Deflection Plates Vertical Deflection Plates Phosphor Screen Electron Beam Electrostatic deflection of the electron beam in a CRT.

12 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 12 A Random scan system draws the Component lines of an object in any order Specified. Random Scan System

13 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 13 A Raster Scan system displays an Object as a set of discrete points Across each scan lines. Raster Scan System

14 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 14 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. Interlacing

15 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 15 Session 3: The Coverage: Color CRT. Shadow Masking. DVST. LED. LCD.

16 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 16 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. A 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. Color CRT Monitors

17 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 17 Magnified Phosphor-Do Triangle screen green red blue Selection Of shadow Masking Shadow Masking Electron Guns

18 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 18 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 Dont 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. Direct -View Storage Tubes

19 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 19 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. Light Emitting Diodes

20 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 20 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). Liquid Crystal Display

21 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 21 Session 4: The Coverage: *Introduction of Scan conversion. *Scan about a point. *Scan about a line.

22 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 22 Introduction Scan Converting About a POINT. a LINE. a CIRCLE. an ELLIPSE. Side effects of Scan Conversion Scan Conversion

23 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 23 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. Introduction

24 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 24 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) Pixel grid Pixel Coordinates Pixel Coordinates Pixel Grid x y x y P1(1.7,0.8) P2(2.2,1.3) P3(2.8,1.9) P1(1.7,0.8) P2(2.2,1.3) P3(2.8,1.9) Scan Converting a point Scan Converting Point

25 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 25 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. x y Y X (X2,y2) (X1,y1) The Straight Line Scan Converting a Scan Lines

26 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 26 Session 5: The Coverage: *Introduction To Line Drawings: BRESENHAMS Algorithm. DDA Algorithm

27 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 27 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. x y Xi Xi+1 Yi Yi+1 P1 t s T S Scan-Converted Points True Line Bresenham's Line Algorithm

28 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 28 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. DDA line Algorithm

29 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 29 Session 6: The Coverage: *Scan Conversion of a Circle *Defining a Circle.

30 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 30 A Circle is the Symmetrical Figure. Any Circle Generating algo take advantage of the circles 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. x y (X,Y) (Y,X) (-Y,X) (-X,Y) (-x,-y) (-y,-x)(y,-x) (x,-y) Scan Converting a Circle

31 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 31 x y x y P=(Xi r 2 x 2 rcos x y r P= (r cos, r Sin Circle defined with a second –egree Polynomial equation. Circle defined with trigonometric functions Defining a Circle

32 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 32 Session: 7 The Coverage: *Scan Conversion of Ellipse. *Side Effects.

33 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 33 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) 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 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 a (Y-k) 2 b = 1Where (h,k) ellipse center a= length of major axis. B= length of minor axis k a 2 x-h 2 By aAnd floating point Multiplication of the square root [1 –(x-h) 2 ]By b. Scan -Converting an Ellipse

34 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 34 1.ALIASING 2.Overstrike Side Effects of Scan Conversion

35 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 35 Session: 8 The Coverage: Transformations. Transformation Types. Geometric Transformation.

36 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 36 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. 2D Graphics Transformation

37 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 37 Transformation Types: Geometric Transformation Coordinate transformation Composite Transformation

38 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 38 x y 0 Object 0x y p p Object 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. Geometric Transformation

39 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 39 Session: 9 The Coverage: *Coordinate Transformation. *Composite Transformation. * Concatenation of matrices.

40 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 40 X Y X Y P(x,y)(x,y) O O Y 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 xy.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. Coordinate Transformation

41 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 41 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 TransformationsCoordinate Transformations R = Cos -Sin sin cos Cos Sin sin cos - R S S X. S Y = S X 0 0S Y S X. S Y = S X 0 0S Y 1 1 Composite Transformation

42 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 42 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. Concatenation Of Matrices

43 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 43 Session: 10 The Coverage: Viewing and clipping. Window to view port Mapping.

44 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 44 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 World Coordinate System Viewport Workstation Window Workstation Viewport 2D Viewing & Clipping

45 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 45 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). 0 0 wy wx vy 1 WINDOW VIEWPORT Window To View port Mapping

46 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 46 Session: 11 The coverage: Cohen Sutherland algorithm. Introduction to Interactive Graphics.

47 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 47 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

48 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 48 Pictorial View: Coheb Sutherland Algorithm

49 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 49 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. Interactive Graphics:

50 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 50 Session: 12 The Coverage: Interactive Graphics Techniques. * Introduction of GKS.

51 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 51 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. Interactive Graphical Technique

52 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 52 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. Graphical Kernel System Introduction:

53 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 53 Session: 13 The Coverage: GKS primitives. GKS AS programming Language.

54 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 54 The graphics kernel System is based on four basic primitives: POLYLINE POLYMARKER FILL AREA TEXT GKS primitive attributes

55 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 55 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) Primitive basics:

56 An ISO 9001:2008 Certified Organization Computer Graphics

57 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 57 SESSION - 1

58 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 58 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

59 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 59 Introduction of Computer and Graphic Computer: - Hardware Software Graphics:- Images Animation Picture Movies and figures, e.t.c L1-2

60 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 60 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

61 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 61 Area of Computer Graphic General Special L1-4

62 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 62 General Industry Medical Business Government Education and training Entertainment Defense Home Agriculture L1-5

63 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 63 Special Mathematical Ele. Industry Statistical Finance Government Defense Art and Design L1-6

64 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 64 Types of Computer Graphic Passive Graphic Interactive Graphic L1-7

65 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 65 Passive Graphics A Computer Graphics Operation that transforms automatically and Without operator intervention. L1-8

66 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 66 Interactive Graphics: As per the framework, a computer receives input from interaction devices, and output images to a display device. L1-9

67 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 67 The S/W has 3 components: 1)Application Program: It Creates, Stores, and retrieves the input. 2)Application Model: It is a combination of object, data and relationship. 3)Graphics System: This is responsible for actually producing the picture from the detailed descriptions. L1-1 0

68 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 68 Conceptual framework for Interactive Graphics: Graphics System Application Model Application Program Display Device/PC L1-11

69 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 69 View of Interactive Graphics Geometric Graphic: - »Explicit Declaration »Select Criteria for insertion. NonGeometric Graphics: - »Implicit Declaration »Simple way of Insertion. L1-12

70 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 70 Summary L1-13

71 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 71 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

72 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 72 Questions L1-15

73 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 73 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

74 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 74 Question 2. What are the various types of Computer Graphics? And where they are used? L1-17

75 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 75 Question 3. Explain the Framework of Interactive Graphics? L1-18

76 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 76 SESSION - 2

77 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 77 Index Advantages of Computer Graphics. Usage of Computer Graphics. Overview of Display Devices. »Monitors »Tubes »CRTs »Random and Raster Scan

78 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 78 Advantages of Interactive Graphics Most Efficient way of communication Expressive way of presentation Interactive C.G

79 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 79 Dynamic way of Picturing and fast processing. Update Dynamically High quality

80 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 80 User Interfaces Interactive plotting in business,Science and Technology. Office automation and E- Publishing. Computer-aided and Design Usage of Computer Graphics:

81 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 81 Simulation and animation for scientific visualization and entertainment. Art and Commerce. Process Control. Cartography.

82 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 82 Overview of Display Devices. Monitors –Tubes Printers

83 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 83 Monitors Tubes –Refresh CRT. Random and Raster Scan Monitor. Color CRT Monitors.

84 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 84 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.

85 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 85 Refresh 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. Figure: Basic Design of a magnetic-deflection CRT

86 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 86 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.

87 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 87 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.

88 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 88 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.

89 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 89 1.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.

90 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 90 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.

91 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 91 Architecture of Random Scan System System Bus I/O DEVICES CPU System Memory Display Processor Monitor

92 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 92 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. Raster Scan System

93 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 93 Architecture of Raster Scan System System Bus I/O DEVICES CPU System Memory Display Processor Monitor Display Processor Memory System Memory Video Controller

94 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 94 Random-Scan and Raster-Scan Random-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

95 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 95 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. Interlacing

96 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 96 Questions

97 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 97 Question 1. What are Raster-Scan Graphic Systems? How does Raster-Display Processor play an important role in its functioning? Explain.

98 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 98 Question 2. Write a short note on 1)i) Random scan monitors 2)ii) Raster scan monitors

99 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 99 Question 3. Explain the working of CRT ? What are the primary components of CRT? What are the needs of CRT refreshing?

100 An ISO 9001:2008 Certified Organization Lecture - 3

101 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 101 Index Color CRT. Shadow CRT DVST(Direct-View Storage Tubes) Shadow Masking Flat Panel Display LED(Light Emitting Diode) LCD

102 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 102 A 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.

103 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 103 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.

104 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 104 Shadow Masking

105 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 105 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.

106 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 106 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.

107 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 107 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: - I.Primary gun is used to store the picture pattern. II.The flood gun,maintain the picture display. Direct -View Storage Tubes

108 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 108 They Dont 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.

109 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 109 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.

110 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 110 Basic design of a plasma-panel display device

111 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 111 Basic design

112 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 112 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.

113 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 113 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. Liquid-crystal Displays (LCDs)

114 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 114 A hand calculator with an LCD screen

115 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 115 The light-twisting, shutter effect used in the design of most liquid-crystal display devices

116 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 116 Question

117 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 117 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.

118 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 118 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.

119 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 119 Question – 3 What are Raster-Scan Graphic Systems? How does Raster-Display Processor play an important role in its functioning? Explain.

120 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 120 Question - Differentiate the working principles of LCD and Plasma Panel Displays.

121 An ISO 9001:2008 Certified Organization SESSION – 4

122 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 122 INDEX Hard Copy Device Laser Printer Ink – Jet Printer. Electrostatic device Place Pen Plotter.

123 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 123 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.

124 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 124 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

125 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 125 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.

126 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 126 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.

127 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 127 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.

128 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 128 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.

129 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 129 Question

130 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 130 Question -1 Write a short note on hard copy devices.

131 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 131 Question -2 Discuss the detailed of DVST.

132 An ISO 9001:2008 Certified Organization SESSION - 5

133 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 133 INDEX Introduction Scan-converting a Point Scan-converting a Straigh Line

134 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 134 INTRODUCTION – Converting binary values stored. pixel-on pixel-off information. – More Complex graphics objects Points Lines Circles Ellipses.

135 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 135 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.

136 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 136 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).

137 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 137 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.

138 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 138 THE LINE

139 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 139 Direct Use Of Line Equation First scan-convert P 1 and P 2 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

140 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 140 Example

141 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 141 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

142 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 142 E2. What steps are required to plot a line whose slope is between 0 o and 45 o using the slope-intercept equation 1.Compute dx: dx = x 2 - x 1. 2.Compute dy: dy = y 2 – y 1. 3.Compute m: m = dy/dx. 4.Compute b: b = y 1 – m x 1.

143 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | Set (x, y) equal to the lower left-hand endpoint and set x end equal to the largest value of x. If dx 0, then x = x 1, y = y 1, and x end = x 2. 6.Test to determine whether the entire line has been drawn. If x > x end, stop. 7.Plot a point at the current (x, y) coordinates.

144 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | Increment x: x = x Compute the next value of y from the equation y = mx + b. 10.Go to step 6.

145 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 145 Use pseudo-code to describe the steps that are required to plot a line whose slope is between 45 o and –45 o (i.e., [m] > 1) using the slope-intercept equation. Presume y 1 < y 2 for the two endpoints (x 1, y 1 ) and (x 2, y 2 ): int x = x 1, y = y 1; float x f, m = (y 2 – y 1 )/(x 2 - x 1 ), b = y 1 = mx 1 ; Set Pixel (x, y); while (y < y2); y++; x f = (y – b)/m;x = Floor(x f + 0.5); Set Pixel (x, y);}

146 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 146 Question

147 © Copyright PCTI Group 2009 Presentation Title | January 11, 2014 | 147 Question -1 How is the point displayed on the graphics scale?


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