Master of Computer Application (MCA) Semester 3

NAME - KRUSHITHA.V.P

ROLL NO. - 520791371ASSIGNMENT 1SUBJECT - MC0072 COMPUTER GRAPHICSMaster of Computer Application (MCA) Semester 3

MC0072 Computer Graphics

Assignment Set 1

1. Describe the following:

A) Image Processing as Picture Analysis B) Advantages of Interactive Graphics

C) Representative Uses of Computer Graphics

Ans:-The computer graphics is one of the most effective and commonly used way to communicate the processed information to the user. It displays the information in the form of graphic objects such as pictures, charts, graphs and diagrams instead of simple text. In computer graphics, pictures or graphics objects are presented as a collection of discrete picture elements called pixels. The pixel is a smallest addressable screen element. It is the smallest piece of the display screen which we can control. The computer graphics allows rotation, translation, scaling and performing various projection on the picture before displaying it..A) Image Processing as Picture AnalysisThe computer graphics is a collection, contribution and representation of real or imaginary objects from their computer based models. So we can say that computer graphics concerns the pictorial synthesis of real or imaginary objects. However, the related field image processing or sometimes called picture analysis concerns the analysis of scenes, or the reconstruction of models of 2D or 3D objects from their picture. This is exactly the reverse process.The image processing can be classified into three types:- Image enhancement Pattern detection and recognition Scene analysis and computer vision

The image enhancement deals with the improvement in the image quality by eliminating noise or by increasing image contrast.

Pattern detection and recognition deal with the detection and clarification of standard patterns and finding deviations from these patterns. The optical character recognition (OCR) technology is a practical example of pattern detection and recognition.

Scene analysis and computer vision deals with the recognition and construction of 3D model scene from several 2D images.

These three fields of image processing proved their importance in many areas such as finger print detection and recognition, modeling of ships, automobiles, buildings etc.,.

B) Advantages of Interactive Graphics

The advantages of interactive graphics are as follows:- In todays world, a high quality graphics display of personal computer provide on of the most natural means of communication with a computer.

Interactive graphics has an ability to show moving pictures, and thus it is possible to produce animations with it.

It provides tools for producing pictures not only of concrete, real-world objects but also of abstract, synthetic objects, such as mathematical surfaces in 4D and of data that have no inherent geometry, such as survey results. The interactive graphics also provides facility called Update Dynamics. With update dynamics it is possible to change the shape, colour or other properties of the objects being viewed.

With interactive graphics we can also control the animation by adjusting the speed, the portion of the total scene in view, the geometric relationship of the objects in the scene to one another, the amount of detail shown and so on. The interactive graphics provides tool called Motion dynamics. With this tool the user can move and tumble objects with respect to a stationary observer, or he can make objects stationary and the viewer moving around them. A typical example is walk through made by builder to show flat interior and building surroundings. In lot of cases, it is also possible to move both objects and viewer.

With the recent development of digital signal processing (DSP) and audio synthesis chip, the interactive graphics can now provide audio feedback along with the graphical feedbacks to make the simulated environment even more realistic.Totally, interactive graphics permits extensive, high-bandwidth user-computer interaction. It significantly enhances the ability to understand information, to perceive trends and to visualize real or imaginary objects either moving or stationary in a realistic environment. It also makes possible to get high quality and more precise results and products with lower analysis and design cost.

C) Representative Uses of Computer Graphics

The Computer graphics uses are wide spread. It is used in various areas such as industry, business, government organizations, education, and entertainment and most recently the home. User Interfaces: User friendliness is one of the main factors underlying the success and popularity of any system. It is well known established fact that graphical interfaces provide and attractive and easy interaction between users and computers. The built-in graphics provide the user interfaces use visual control items such as buttons, menus, icons, scroll bar etc, which allows user to interact with computer only by mouse-click. Typing is necessary only to input text to be stored and manipulated.

Office automation and Desktop Publishing: The desktop publishing on personal computers all the use of graphics for the creation and dissemination of information. Many organizations does the in-house creation and printing of documents. The desktop publishing allows user to create documents which contains text, tables, graphs and other forms of drawn or scanned images or pictures. This is one such approach towards the office automation.

Plotting of graphics and chart: In industry, businesses, government and educational organizations, computer graphics is mostly used to create 2D and 3D graphs of mathematical, physical and economic functions in form of histograms, bars and pie-charts. These graphs and charts are very useful for decision making. Computer-aided Drafting and Design.: The computer aided drafting uses graphics to design components and systems electrical, mechanical, electromechanically and electronic devices such as automobile bodies, structures of building, airplane, ships, very largescale integrated (VLSI) chips, optical systems and computer networks.

Art and Commerce; There is a lot of development in the tools provided by computer graphics. This allows user to create artistic pictures which express messages and attract attentions. Such pictures are very useful in advertising.

Simulation and Animation: Use of graphics in simulation makes mathematical models and mechanical systems more realistic and easy to study. The interactive graphics supported by animation software proved their use in production of animated movies and cartoon films.

Process Control: By the use of computer it is now possible to control various processes in the industry from a remote control room. In such cases, process systems and processing parameters are shown on the computer with graphic symbols and identifications. This makes it easy for operator to monitor and control various processing parameters at a time.

Cartography: Computer graphics is also used to represent geographic maps, weather maps, oceanographic charts, contour maps, population density maps and so on.

3. Explain the following with respect to Graphics Hardware:

A) Graphics Workstation

B) Video Controller

C) Color Tables

A) Graphics WorkstationGraphics Workstation is the Graphics Kernel Systems (GKS) term for a graphical device that can display graphical output or accept graphical input or both. We can show the graphics station through a block diagram. The block diagram consists of CPU, display processor, memory, display services, recorder, plotter, keyboard, joystick, light pen mouse, scanner etc. The main hardware components of a graphics workstation are CPU and Display Processor. The display processor is also called a graphics controller or a display coprocessor. It makes CPU from graphical chores. Other than that, there is also a separate display processor memory area is provided in graphics workstation. Graphics workstations have a provision to interface video cameras and television sets. The size of the display device, colors supported by it, whether it is a raster or line drawing device are the main properties of the graphics workstation. It is always supported with graphics software. Graphics software acts as a very powerful tool to create scenes, images, pictures and also animated pictures.B) Video Controller

Video controller receives the intensity information of each pixel from frame buffer and displays them on the screen.

The internal organization of video controller consists of raster-scan generator, x and y address registers and pixel value register. The raster-scan generator produces deflection signals that generate the raster scan. The generator also controls the x and y address registers which in turn define the memory location to the accessed next. Frame buffer locations and the corresponding screen positions, are referenced in Cartesian coordinates. For many graphics monitors, the coordinate origin is defined at the lower left screen corner. The screen surface is then represented as the first quadrant of a two-dimensional system, with positive x values increasing to the right and positive y values increasing from bottom to top. (In some personal computers the y values are inverted). Scan lines are then labeled from y, at the top of the screen to 0 at the bottom. Along each scan line, screen pixel positions are labeled from 0 to x max. During each fetch the pixel value is read an d is used to control the intensity of the CRT beam.

C) Color TablesIn color displays, 24-bits per pixel are commonly used, where 8-bits represent 256 levels for each color. Here it is necessary to read 24-bits for each pixel from frame buffer. This is very time consuming. To avoid this, video controller uses look up table (LUT) to store many entries of pixel values in RGB format. With this facility, now it is necessary only to read index to the look up table from the frame buffer for each pixel. This index specifies the one of the entries in the look-up table. The specified entry in the look up table is then used to control the intensity or color of the CRT.Usually, look-up table has 256 entries. Therefore, the index to the look-up table has 8-bits and hence for each pixel, the frame buffer has to store 8-bits per pixel instead of 24 bits.

There are several advantages in storing color codes in a look-up table. Use of a color table can provide a reasonable number of simultaneous colors without requiring large frame buffers. For most applications, 256 or 512 different colors are sufficient for a single picture. Also, table entries can be changed at any time, allowing a user to be able to experiment easily with different color combinations in a design, scene or graph without changing the attribute settings, for the graphics data structure. In visualization and image processing applications, color tables are convenient means for setting color thresholds so that all pixel values above or below a specified threshold can be set to the same color. For these reasons, some systems provide both capabilities for color-code storage, so that a user can select either to use color tables or to store color codes directly in the frame buffer.4. Describe the following:

A) Basic Concepts in Line Drawing

B) Digital Differential Analyzer Algorithm

C) Bresenhams Line Drawing Algorithm

A) Basic concepts in Line Drawing

There are some general requirements for algorithms for line drawing. These requirements specify the desired characteristics of line. 1. The line should appear as a straight line and it should start and end accurately.

2. The line should be displayed with constant brightness along its length independent of of its length and orientation. 3. The line should be drawn rapidly.

The vertical of the line is dependent on the orientation of the line.

Digital Differential Analyzer

The differential analyzer was a mechanical analog computer designed to solve differential equations by integration, using wheel-and-disc mechanisms to perform the integration. It was one of the first advanced computing devices to be used operationally.

A Digital Differential Analyzer (DDA), also sometimes called a Digital Integrating Computer[1], is a digital implementation of a Differential Analyzer. The integrators in a DDA are implemented as accumulators, with the numeric result converted back to a pulse rate by the overflow of the accumulator.

The primary advantages of a DDA over the conventional analog Differential Analyzer are greater precision of the results and the lack of drift/noise/slip/lash in the calculations. The precision is only limited by register size and the resulting accumulated rounding/truncation errors of repeated addition. Digital electronics inherently lacks the temperature sensitive drift and noise level issues of analog electronics and the slippage and "lash" issues of mechanical analog systemsc. Midpoint Line Drawing Algorithm:

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