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Introduction to Computer Graphics and Multimedia, 2/e. Anirban Mukhopadhyay & Arup Chattopadhyay. Vikas Publishing. ; pages. Anirban Mukhopadhyay is the author of INTRODUCTION TO COMPUTER GRAPHICS AND MULTIMEDIA - SECOND EDITION ( avg rating, 16 ratings, . Introduction to Computer Graphics,. Anirban Mukhopadhyay, Arup. Chattopadhyay. COMPUTER GRAPHICS, Donald Haern,. M. Pauline Baker ( Second Edition).

Introduction To Computer Graphics By Anirban Mukhopadhyay Pdf

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Introduction to Computer Graphics and Multimedia - 2nd Edition [Anirban Mukhopadhyay, Arup Chattopadhyay] on yazik.info *FREE* shipping on qualifying. Introduction to Computer Graphics and Multimedia - Second Edition by Anirban Mukhopadhyay, , available at Book Depository with free. Computer Graphics Introduction to Computer Graphics, Anirban Mukhopadhyay, Arup Chattopadhyay COMPUTER GRAPHICS, Donald Haern, M. This 3D.

A book which deals with the fundamentals of the subject in an easy-to-understand manner without attempting to unfold the myriad of intricate details where the students are susceptible to get bogged down and finally lose interest. The book should provide a path through the complexities of the subject and optimally provide the necessary technical and mathematical background required for studying the subject. A book which is comprehensive and explains the elements from theory to implementation and most importantly has content suited to the common requirements of computer graphics paper in different universities in our country.

A book which will provide features of popular graphics applications with brief discussion of underlying technicalities and encourage students for advanced studies in computer graphics and related fields. With the above requirements in view, we have tried to make the book complete and suitable as a text or supplementary text for an introductory course in computer graphics. Since study of computer graphics calls for knowledge of basic high school level mathematics including two and three dimensional analytical geometry, trigonometry, vectors and matrix operations, chapter two will provide a ready reference of necessary formulae, rules and definitions.

Numerous examples and solved problems with illustrations have been given in most of the chapters to consolidate the concepts discussed; review questions collected from various universities and institutes all over India are given at the end of each chapter and this will help the students prepare well for examination. Read more Read less.

Product details Paperback: English ISBN Be the first to review this item site Best Sellers Rank: Tell the Publisher! I'd like to read this book on Kindle Don't have a Kindle? No customer reviews. Share your thoughts with other customers.

Write a customer review. There's a problem loading this menu right now. Learn more about site Prime. Get fast, free shipping with site Prime. Back to top. Get to Know Us. site Payment Products. English Choose a language for shopping. The output of a scanner is a bitmap file b OCR document c graphics metafile d postscript file Figure 1. Light Pen 2. Which of the following Light pens are popularly used to digitize map or engineering drawing or signature or components are common handwriting.

A keyboard can be called a allows the user to virtually touch an object displayed on the same monitor. With the object a locator device animated it would appear that the user wearing the data glove can pick up an object and b valuator device do things with it just as he would do with a real object.

In modern data glove devices, tactile c string device sensors are used to provide the user with an additional feeling of touch or the amount of d all the above pressure or force the fingers or hands are exerting even though the user is not actually touching anything. Thus data glove is an agent to transport the user to virtual reality. Data Glove 1. A dictionary is established for a particular operator voice by recording the frequency-patterns of the voice commands words spoken and corresponding functions to be performed.

Later when a voice command is given by the same operator, the system searches for a frequency-pattern match in the dictionary and if found the corresponding action is triggered. An application program can make simultaneous use of several input devices operating in different modes. For example, a keyboard, a mouse, a scanner and a voice system can all be attached to the same computer interacting through the same or different graphical user interfaces.

Many input devices are multifunctional and so more than one device can provide the same class of input data. Still the popularity of input devices varies based on the functional capabilities and users convenience. However, devices like data glove, webcam and bar-code reader are popular in specialized applications for their unique functionality. NOTES 1. Describe the touch-sensing mechanism as used in a touch panel. What are the advantages of feedback in graphical input techniques? What is position interaction task?

Briefly discuss the main issues.

SCS Computer Graphics Course Outline.pdf - SCS

Enumerate the differences between pointing devices and positioning devices. Explain how users can interact with a virtual screen. List the typical inputs that are used with VR systems. Compare the working device used in touch panel and light pen.

Compare the working of a locator device and valuator device. Hearn, Donal and M. Pauline Baker, Computer Graphics. Rogers, David F. Mukhopadhyay A. Chattopadhyay, Introduction to Computer Graphics and Multimedia. An Overview 2. Though plotters have limited and specialized uses, printer is a common yet important accessory of any computer system, specially for a graphics system.

In keeping with its importance in real life there have been close competitions amongst the manufacturers in developing newer and cheaper models of hardcopy devices ranging from low cost dot matrix and popular deskjets to heavy duty laserjets or sophisticated pen plotters.

This unit describes various hardcopy technologies and functional aspects of a variety of printers and plotters. This is because most of the graphics creation using computer graphics has its ultimate utilization in printed form — for documentation, exhibition or publication in print media or books.

It is the quality of printed output that finally matters in many businesses. Based on the available printing technology the major factors which control the quality of printer are individual dot size on the paper and number of dots per inch dpi. Clearly, the lesser the size of the dots the better the detail of the figure reproduced. Higher dpi values increase the sharpness and detail of a figure and enhance the intensity levels that a printer supports.

Other important factors for selection of a printer are printing speed and print area or printer memory. Non-impact There are several major printer technologies available.

Anirban Mukhopadhyay And Arup Chattopadhyay

These technologies can be broken down into two main categories with several types in each: These printers have a mechanism whereby formed character faces are NOTES pressed against an inked ribbon onto the paper in order to create an image. For example, dot matrix printer and line printer. These printers do not touch the paper rather use laser techniques, ink sprays, xerographic processes and electrostatic methods to produce the image on paper.

For example, laser printer, inkjet printer, electrostatic printer, drum plotter, flatbed plotter. Unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the printing involves mechanical pressure, these printers can create carbon copies. The print head normally prints along every raster row of the printer paper and the colour of print is the colour of the ink of the ribbon.

The pins are usually arranged vertically where marginal offsets are provided between columns to reduce inter-dot spacing. The position of pins in the print head actually limits the quality of such a printer. Hardware improvements to dot matrix printers boosted the carriage speed, added more typeface font options, increased the dot density from 60dpi up to dpi , and added pseudo-colour printing through multi-colour ribbon.

Still such printers lack the ability to print computer-generated images of acceptable quality. It is good for text printing in continuous sheets. In a typical design, a fixed font character set is engraved onto the periphery of a number of print wheels, the number matching the number of columns letters in a line. As the desired character for each column passes the print position, a hammer Hardcopy Devices strikes the paper and ribbon causing the desired character to be recorded on the continuous paper.

Printed type is set at fixed positions and a line could consist of any number of character positions with columns as the most common, but 80 column, column and column variants are also in use. The line printer technology is usually both faster and less expensive in total ownership than laser printers. It has its use in medium volume accounting and other large business applications, where print volume and speed is a priority over quality. Because of the limited character set engraved on the wheels and the fixed spacing of type, this technology was never useful for material of high readability such as books or newspapers.

Figure 2.

Introduction To Computer Graphics & Multimedia, 2E Pdf

Line Matrix Printer 2. These printers are popular because they less costly but generate attractive graphic output.

The dots can have different colours combined together to create photo-quality images. The core of an inkjet printer is the print head that contains a series of nozzles that are used to spray drops of ink. The ink is contained in ink cartridges that come in various combinations, such as separate black and colour cartridges, or a cartridge for each ink colour. A stepper motor moves the print head assembly print head and ink cartridges back and forth across the paper.

The mechanical operation of the printer is controlled by a small circuit board containing a microprocessor and memory. There are two main inkjet technologies currently used by printer manufacturers. This is used by manufacturers such as Canon and Hewlett Packard. In a thermal inkjet printer, tiny resistors create heat, and this heat vaporizes ink to create a bubble.

As the bubble expands, some of the ink is pushed out of a nozzle onto the paper. This pulls more ink into the print head from the cartridge. A typical bubble jet print head has or tiny nozzles, and all of them can fire a droplet simultaneously.

Patented by Epson, this technology uses piezo crystals. A crystal is located at the back of the ink reservoir of each nozzle. The crystal receives a tiny electric charge that causes it to vibrate. When it vibrates out, it pulls some more ink into the reservoir to replace the ink sprayed out. A laser beam focuses a positively charged selenium-coated rotating drum.

The laser gun removes the positive charge from the drum except for the area to be printed black portion of the paper. In this way, the laser draws the letters and images to be printed as a pattern of electrical-charges — an electrostatic image. The negatively-charged black toner powder first adheres to this positively-charged area image on the drum from where it is transferred to the rolling white paper. Before the paper rolls under the drum, it is given a positive charge stronger than the positive charge of the electrostatic image, so the paper can pull the toner powder away.

The paper is then subjected to mild heating to melt and fix the loose toner on the paper. The laser printer is mainly a bilevel printer. In case of colour lasers, this process is repeated three times.

For the printer controller and the host computer to communicate, they need to speak the same page description language. Both these languages describe the page in vector form — that is, as mathematical values of geometric shapes, rather than as a series of dots a bitmap image.

Apart from image data the printer controller receives all of the commands that tell the printer what to do — what paper to use, how to format the page, how to handle the font, etc. Accordingly the controller sets the text margins, arranges the words and places the graphics. When the page is arranged, the raster image processor RIP takes the page data, either as a whole or piece by piece, and breaks it down into an array of tiny dots so the laser can write it out on the photoreceptor drum.

In most laser printers, the controller saves all print-job data in its own memory. This lets the controller put different printing jobs into a queue so it can work through them one at a time.

Image Creation by the Laser on Drum 2. In contrast, the electrostatic printer has many print heads, actually covering the entire 36" media width. So instead of a single print head moving across the width of the media, the electrostatic printer prints an entire width of the page at one time.

The media paper, vellum, film is electrostatically charged energized. The printer creates colour prints by breaking colour data down into three basic colours cyan, magenta, and yellow plus black, and printing one colour at a time. In 5-pass print mode, combinations of cyan, magenta, yellow and black provide a wide range of different colours. Using the registration marks printed during the preliminary registration pass ensures that the colour plot is beautiful with no misalignment.

Which of the following is not a printer language? HP Electrostatic Printer d dot matrix printer and pen plotter 2. For which of the following In contrast to the printer which is primarily a raster scan device, the plotter is a vector pair of hardcopy devices is device. In colour plotters the carriage accommodates a number of pens with varying colours the nature of ink or printing material not identical? In flat bed plotter the paper lies flat and stationary c Inkjet printer and wet- while the pen moves from one location to another on the paper.

But in drum plotters the ink pen plotter paper itself slides on a cylindrical drum and the pen moves over the drum. Flatbed Plotter and Drum Plotter 2. The technology used by these devices ultimately constrains the quality of realistic graphics. So the knowledge of printing technology and printer or plotter capabilities is needed to make an optimized use of resources and generate output of acceptable accuracy w.

In addition to the printers discussed in this unit there are costlier varieties as dye-sublimation printer, thermal wax printer and thermal autochrome printer. The autochrome printers have three layers cyan, magenta and yellow that colour in the paper instead of in the printer.

Most interestingly some thermal printer accepts video signals thus creating hardcopy of video images. Looking at the future of printer the one which is very much in the line of evolution is the Bluetooth-enabled wireless printer. Compare the working of a digitizer with that of a plotter. Explain the laser printer with reference to the following points: Compare the working principles of the electrostatic printer with that of a laser printer.

For an electrostatic printer with an inch wide paper, a resolution of units to the inch in each direction, and a paper speed of 3 inches per second, how many bits per second must be provided to allow the paper to move at full speed?

Describe briefly how a computer communicates with a laser printer. CRT display is by far the most common display technology and most of the fundamental display concepts are embodied in CRT technology.

This unit focuses on CRT-based display technologies explaining the related concepts followed by illustrations of structural and functional components and working principles of each. The unit briefly explains few other common display technologies. To understand how digital video is used as a media we need to understand some fundamental aspects of analog video technology. Basically video or motion pictures are created by displaying images depicting progressive stages of motion at a rate fast enough so that the projection of individual images overlap on the eye.

Persistence of vision of human eye, which allows any projected image to persist for 40—50 ms, requires a frame rate of 25—30 frames per second to ensure perception of smooth motion picture. Constitution-wise there are three types of video signals: Component video, Composite video and S-video. Most computer systems and high-end video systems use component video whereby three signals R, G and B are transmitted through three separate wires corresponding to red, green and blue image planes respectively.

However, because of the complexities of transmitting the three signals of component video in exact synchronism and relationship these signals are encoded using a frequency- interleaving scheme into a composite format that can be transmitted through a single cable. Such format known as composite video, used by most video systems and broadcast TV, uses one luminance and two chrominance signals.

Luminance Y is a monochrome video signal that controls only the brightness of an image. Component video gives the best output since there is no cross-talk or interference between the different channels unlike composite video or S-video. In a television transmission system, every part of every moving image is converted into analog electronic signals and is transmitted. There are three main standards for analog video signals used in television transmission: A characteristic comparison of these standards is listed in the Table 3.

Video digitization is achieved just like audio digitization by sampling the analog video signal at a preset frequency and subsequently quantizing the discrete samples in digital format.

This is done with the help of analog to digital converter or ADC. There are two kinds of possible digitizations or digital coding—Composite coding and Component coding. In composite coding, all signal components taken together as a whole are converted into digital format. In component coding, each signal component is digitized separately using different sampling frequency The main function of the video frame grabber card is to take the composite luminance- chrominance analog video signal, decode it to RGB signal, then convert it to the digital format and store each frame first in the frame buffer on the card itself.

At an adequate frame-rate consecutive frames are streamed to the monitor, routed through the frame buffer of the main memory to present live video on the computer screen. How closely the digital video approximates the original analog video depends on the sampling resolution or number of bits used to represent any pixel value.

Storing video on digital devices memory ready to be processed, noise removal, cut and paste, size and motion control and so on and integrated into various multimedia applications is possible. NOTES 2. It allows direct access, which makes non-linear video editing audio mixing, adding text, titles and digital effects etc. It allows repeated recording without degradation of image quality.

Ease of encryption and better tolerance to channel noise is possible. HDTV standard that support progressive non-interlaced video scanning; has much wider aspect ratio Now imagine the storage space required for a 2-hour movie. So the only way to achieve digital motion video on PC is to reduce or compress the redundant data in video files.

Redundancy in digital video occurs when the same information is transmitted more than once. Primarily in any area of an image frame where same colour or intensity spans more than one pixel location, there is spatial redundancy. Secondly, when a scene is stationary or only slightly moving, there is redundancy between frames of motion sequence — the contents of consecutive frames in time are similar, or they may be related by a simple translation function.

This kind of redundancy is called temporal redundancy. Spatial redundancy is removed by compressing each individual image frame in isolation and the techniques used are generally called spatial compression or intra-frame compression. Temporal redundancy is removed by storing only the differences of subsequence of frames instead of compressing each frame independently and the technique is known as temporal compression or inter-frame compression.

Spatial compression applies different lossless and lossy method same as those applied for still images. Some of these methods are: The compare should produce zero for pixels, which have not changed, and non-zero for pixels, which are involved in motion. Only then can the pixels with non-zero differences be coded and stored, thus reducing the burden of storing all the pixel value of a frame.

Firstly, the even if there is no object motion in a frame, slightest movement of camera would produce non-zero difference of all or most pixels. Secondly, quantization noise would yield non-zero difference of stationary pixels. Such approach of temporal compression is said to be based on motion compensation.


The current image frame is referred to as target frame. This examination is known as forward prediction or backward prediction depending on whether the reference frame is a previous frame or next frame.

If the target macroblock is found to contain no motion, a code is sent to the decompressor to leave the block the way it was in the reference frame. If the block does have motion the motion vector and difference block need to be coded so that the decompressor can reproduce the target block from the code. The datastream architecture is based on a sequence of frame, each of which contains the data needed to create a single displayed image. There are four different kind of frames, depending on how each image is to be decoded: I-frames Intra-coded images are self-contained, i.

These frames are purely spatially compressed using a transform coding method similar to JPEG. An I-frame must exist at the start of any video stream and also at any random access entry point in the stream. P-frames Predictive-coded images are compressed images resulting from removal of temporal redundancy between successive frames.

These frames are coded by a forward predictive coding method in which target macroblocks are predicted from most similar reference macroblocks in the preceding I or P-frame. Only the difference between the spatial location of the macroblocks, i. Instead of the difference macroblocks itself is coded as non- motion compensated macroblock when a good match as reference macroblocks is not found.

Usually in P-frames large compression ratio three times as much in I-frames is achieved. Interpolative motion compensation is used here. If matching in both directions is successful, two motion vectors NOTES will be sent, and the two corresponding matching macroblocks will be averaged interpolated for comparing to the target macroblock for generating the difference macroblock. If an acceptable match can be found in only one of the reference frames, then only one motion vector and its corresponding macroblocks is used for generating the difference macroblock.

Maximum compression ratio one and half times as much as in P-frame is achieved in B- frames. D-frames DC-coded frames are intraframe coded and are used for fast forward or fast rewind modes. Hence for 4: As far as the sequence of I, P and B-frames is concerned in a MPEG-1 video datastream, there are certain guiding factors like resolution, access speed and compression ratio. For fast random access, the best resolution would be achieved by coding the whole datastream as I-frames.

On the other hand the highest degree of compression is attained by using as many B-frames as possible. However, to perform B-frame decoding, the future I or P frame involved must be transmitted before any of the dependent B-frames can be processed. This would cause delay in the decoding proportional to the number of B-frames in the series. Sequence layer: A video sequence consists of one or more group of pictures and always starts with a sequence header.

The header contains picture information such as horizontal size and vertical size, aspect ratio, frame rate, bit rate, and buffer size.

These parameters can be changed with optional sequence headers between GOPs. Group of Pictures GOPs layer: A GOP contains one or more pictures or frames at least one of which should be an I-frame. At this layer it is possible to distinguish the order of frames in the datastream with that in the display. But in the order of display, a B-frame can occur before Display Devices an I-frame. Datastream Decoding order: Picture layer: This layer contains a displayable picture. Slice layer: Each slice consists of a number of macroblocks that may vary in a single image.

The length and position of each slice are specified in the layer header. Slices are useful for recovery and synchronization of lost or corrupted bits. Macroblock layer: Each image is divided into macroblocks. The coded blocks are preceded by a macroblock header, which contains all the control information spatial address, motion vectors, prediction modes, quantizer step size etc.

Block layer: Each block contains DC coefficients first, followed by variable length codes VLC and terminated by end-of- block marker. The Programme Map Tables PMTs identifies which audio and video signals go together to make a particular program out of several are channels transmitted. Several approaches have been proposed for standardization of video files architecture but QuickTime has established itself as a de facto standard. NOTES 3. Adobe Premiere is a popular mid-range non-linear video editing application that provides some post-production facilities on desktop platform.

Three windows are used by Premiere namely Project, Timeline and Monitor. Project window is used for importing and displaying raw video and audio clips and still images with all relevant information. The timeline window provides a visual display of the linear extent of the completed movie, showing the order of its component clips. It uses multiple audio and video tracks for transitions and overlays. Audio and video clips can be dragged from the project window and dropped on the timeline for assembly.

Timeline, Project and Monitor Window The monitor window is used for editing and viewing the video frames. Editing includes trimming, overlaying, applying effects like dissolve, wipes, spins and page turns for transition of one clip to another.

Serious post production operations changes like colour and contrast corrections, blurring or sharpening of images, element insertion and compositing, applying filter to a clip and vary it over time, sophisticated interpolation between key frames and so on can be done with more control and perfection by using dedicated post-production softwares like Adobe After Effects.

The display system may be attached to a PC to display character, picture and video outputs.

Detailed Syllabus

Some of the common types of display systems available in the market are: Raster Scan Displays Display Devices 2. Random Scan Displays 3. Direct View Storage Tube 4. Flat Panel Displays 5. The most common video monitor that normally comes with a PC is the Raster Scan type.

However, every display system has three basic parts — the display adapter that creates and holds the image information, the monitor which displays that information and the cable that carries the image data between the display adapter and the monitor. Before we discuss the major display systems let us first know about some basic terms. Any image that is displayed on the monitor is made up of thousands of such small pixels also known as picture elements. The closely-spaced pixels divide the image area into a compact and uniform two-dimensional grid of pixel lines and columns.

Each pixel has a particular colour and brightness value. Though the size of a pixel depends mostly on the size of the electron beam within the CRT, they are too fine and close to each other to be perceptible by the human eye.

The finer the pixels the more the number of pixels displayable on a monitor screen. However, it should be remembered that the number of pixels in an image is fixed by the program that creates the image and not by the hardware that displays it.

One is Image Resolution and the other is Screen Resolution. Strictly speaking image resolution refers to the pixel spacing, i. A typical PC monitor displays screen images with a resolution somewhere between 25 pixels per inch and 80 pixels per inch ppi. In other words, resolution of an image refers to the total number of pixels along the entire height and width of the image.

The internal surface of the monitor screen is coated with red, green and blue phosphor material that glows when struck by a stream of electrons. This coated material is arranged into an array of millions of tiny cells—red, green and blue, usually called dots.

The dot pitch is the distance between adjacent sets triads of red, green and blue dots. This is also same as the shortest distance between any two dots of the same colour, i. Usually monitors are available with a dot pitch specification 0. Each dot glow with a single pure colour red, green or blue and each glowing triad appears to our eye as a small spot of colour a mixture of red, green and blue. Depending on the intensity of the red, green and blue colours different colours results in different triads.

The dot pitch of the monitor thus indicates how fine the coloured spots that make up the picture can be, though electron beam dia is an important factor in determining the spot size.

Pixel therefore, is the smallest element of a displayed image, and dots red, green and blue are the smallest elements of a display surface monitor screen.

The dot pitch is the measure of screen resolution. The smaller the dot pitch, the higher the resolution, sharpness and detail of the image displayed. Originally, monitors were fixed at a particular resolution, but for most monitors today display resolution can be changed using software control.

This lets you use higher or lower resolution depending on the need of your application. A higher NOTES resolution display allows you to see more information on your screen at a time and is particularly useful for operating systems such as Windows. However, the resolution of an image you see is a function of what the video card outputs and what the monitor is capable of displaying.

As the image has to fit in the limited resolution of the monitor, the screen pixels comprising a red, a green and a blue dot show the average colour and brightness of several adjacent image pixels. Only when the two resolutions match, will the image be displayed perfectly and only then is the monitor used to its maximum capacity.

The standard aspect ratio for PCs is 4: Monitors are calibrated to this standard so that when you draw a circle it appears to be a circle and not an ellipse. Displaying an image that uses an aspect ratio of 5: The only mainstream resolution that uses 5: Table 3. The CRT works just like the picture tube of a television set. Its viewing surface is coated with a layer of arrayed phosphor dots. At the back of the CRT is a set of electron guns cathodes which produce a controlled stream of electrons electron beam.

The phosphor material emits light when struck by these high-energy electrons. The frequency and intensity of the light emitted depends on the type of phosphor material used and energy of the electrons. To produce a picture on the screen, these directed electron beams start at the top of the screen and scan rapidly from left to right along the row of phosphor dots.

They return to the left-most position one line down and scan again, and repeat this to cover the entire screen. The return of the beam to the leftmost position one line down is called horizontal retrace during which the electron flow is shut off.

In performing this scanning or sweeping type motion, the electron guns are controlled by the video data stream that comes into the monitor from the video card. The instantaneous control of the intensity of the electron Display Devices beam at each dot is what controls the colour and brightness of each pixel on the screen. An image in raster scan display is basically composed of a set of dots and lines; lines NOTES are displayed by making those dots bright with the desired colour which lie as close as possible to the shortest path between the endpoints of a line.

As brightness of the dots begins to reduce, the screen-image becomes unstable and gradually fades out. In order to maintain a stable image, the electron beam must sweep the entire surface of the screen and then return to redraw it a number of times per second. This process is called refreshing the screen. After scanning all the pixel-rows of the display surface, the electron beam reaches the rightmost position in the bottommost pixel line.

The electron flow is then switched off and the vertical deflection mechanism steers the beam to the top left position to start another cycle of scanning.

This diagonal movement of the beam direction across the display surface is known as vertical retrace. If the electron beam takes too long to return and redraw a pixel, the pixel will begin to fade; it will return to full brightness only when redrawn.

Over the full surface of the screen, this becomes visible as a flicker in the image, which can be distracting and hard on the eyes. In order to avoid flicker, the screen image must be redrawn fast enough so that the eye cannot tell that refresh is going on.

The refresh rate is the number of times per second that the screen is refreshed. It is measured in Hertz Hz , the unit of frequency. The refresh rates are somewhat standardized; common values are 56, 60, 65, 70, 72, 75, 80, 85, 90, 95, , and Hz. Though higher refresh rates are preferred for better comfort in viewing the monitor, the maximum refresh rate possible depends on the resolution of the image.

The maximum refresh rate that a higher resolution image can support is less than that supported by a lower resolution image, because the monitor has more number of pixels to cover with each sweep. Actually support for a given refresh rate requires two things: Every monitor should include, as part of its specification, a list of resolutions it supports and the maximum refresh rate for each resolution.

Many video cards now include setup utilities that are pre-programmed with information about different monitors. When you select a monitor, the video card automatically adjusts the resolutions and respective allowable refresh rates.

Windows 95 and later versions extend this facility by supporting Plug and Play for monitors; you plug the monitor in and Windows will detect it, set the correct display type and choose the optimal refresh rate automatically. Some monitors use a technique called interlacing to cheat a bit and allow themselves to display at a higher resolution than is otherwise possible.

Instead of refreshing every line of the screen, when in an interlaced mode, the electron guns sweep alternate lines on each pass. In the first pass, odd-numbered lines are refreshed, and in the second pass, even- numbered lines are refreshed. This allows the refresh rate to be doubled because only half the screen is redrawn at a time. The usual refresh rate for interlaced operation is 87 Hz, which corresponds to There are two separate sets of horizontal and vertical retrace.

It contains three electron guns that emit a focused beam of electrons, deflection apparatus magnetic or electrostatic , which deflects these beams both up and down and sideways, and a phosphor-coated screen upon which these beams impinge. The vacuum is necessary to let those electron beams travel across the tube without running into air molecules that could absorb or scatter them.

The primary component in an electron gun is a cathode negatively charged encapsulated by a metal cylinder known as the control grid. A heating element inside the cathode causes the cathode to be heated as current is passed. These electrons are accelerated towards the CRT screen by a high positive voltage applied near the screen or by an accelerating anode.

If allowed to continue uninterrupted, the naturally diverging electrons would simply flood the entire screen. The cloud of electrons is forced to converge to a small spot as it touches the CRT screen by a focusing system using an electrostatic or magnetic field. Just as an optical lens focuses a beam of light at a particular focal distance, a positively charged metal cylinder focuses the electron beam passing through it on the centre of the CRT screen.

A pair of magnetic deflection coils mounted outside the CRT envelope deflects the concentrated electron beam to converge at different points on the screen in the process of scanning. Horizontal deflection is obtained by one pair of coils and vertical deflection by the other pair, and the deflection amount is controlled by adjusting the current passing through the coils.

When the electron beam is deflected away from the centre of the screen, the point of convergence tends to fall behind the screen resulting in a blurred defocused display near the screen edges. In high-end display devices this problem is eliminated by a mechanism which dynamically adjusts the beam focus at different points on the screen. Figure 3. This causes the electrons in the phosphor atoms to jump to higher energy orbits.

After a short time these excited electrons drop back to their earlier stable state, releasing their extra energy as small quantum of light energy. As long as these excited electrons return to their stable state phosphor NOTES continue to glow phosphorescence but gradually loses brightness. The time between the removal of excitation and the moment when phosphorescence has decayed to 10 per cent of the initial brightness is termed as persistence of phosphor. The brightness of the light emitted by phosphor depends on the intensity with which the electron beam number of electrons strikes the phosphor.

The intensity of the beam can be regulated by applying measured negative voltage to the control grid. Corresponding to a zero value in the frame buffer a high negative voltage is applied to the control grid, which in turn will shut off the electron beam by repelling the electrons and stopping them from coming out of the gun and hitting the screen. The corresponding points on the screen will remain black. Similarly, a bright white spot can be created at a particular point by minimising the negative voltage at the control grid of the three electron guns when they are directed to that point by the deflection mechanism.

Apart from brightness the size of the illuminated spot created on the screen varies directly with the intensity of the electron beam. As the intensity or number of electrons in the beam increases, the beam diameter and spot size increases.

Also the highly excited bright phosphor dots tend to spread the excitation to the neighbouring dots thereby further increasing the spot size. Therefore the total number of distinguishable spots pixels that can be created on the screen depends on the individual spot size. The lower the spot size, the higher the image resolution. In a monochrome CRT there is only one electron gun, whereas in a colour CRT there are three electron guns each controlling the display of red, green and blue light respectively.

Unlike the screen of a monochrome CRT, which has a uniform coating of phosphor, the colour CRT has three colour-phosphor dots dot triad — red, green and blue — at each point on the screen surface. When struck by an electron beam the red dot emits red light, the green dot emits green light and the blue dot emits blue light.

Each triad is arranged in a triangular pattern, as are the three electron guns. The beam deflection arrangement allows all the three beams to be deflected at the same time to form a raster scan pattern. There are separate video streams for each RGB red, green and blue colour components which drive the electron guns to create different intensities of RGB colours at each point on the screen.

To ensure that the electron beam emitted from individual electron guns strikes only the correct phosphor dots e. The mask is a fine metal sheet with a regular array of holes punched in it. The mask is so aligned that as the set of three beams sweeps across the shadow mask they converge and intersect at the holes and then hit the correct phosphor dot; the beams are prevented or masked from intersecting other two dots of the triad.

Thus, different intensities can be set for each dot in a triad and a small colour spot is produced on the screen as a result. Instead of a shadow mask, they use an aperture grill.

In this system, the metal mesh is replaced by hundreds of fine metal strips that run vertically from the top of the screen to the bottom. The gaps between the metal wires allow the three electron beams to illuminate the adjacent columns of coloured phosphor which are arranged in alternating stripes of red, green and blue. This configuration allows the phosphor stripes to be placed closer together than conventional dot triads. The fine vertical wires block less of the electron beam than ordinary shadow masks resulting in a brighter and sharper image.

Trinitron monitors are curved on the horizontal plane and are flat on the vertical plane. For TV sets and monitors, the diagonal dimension is stated as the size. As a portion of the picture tube is covered by the case, the actual viewable portion measures only 19 inches diagonally. For standard monitors the height is about three-fourth of the width.

For a inch monitor the image width will be 15 inches and the height will be 11 inches.Draw a neat block diagram, to explain the architecture of a raster display.

NOTES In many joysticks, optical sensors are used instead of analog potentiometer to read stick movement digitally. About these proceedings Introduction This book contains interesting findings of some state-of-the-art research in the field of signal and image processing. This site is like a library, you could find million book here by using search box in the header. The formula to calculate how much video memory is required at a given resolution and bit depth is: However, this book is intended for graduate-level students.

In acoustic type, similar to the light rays, sonic beams are generated from the horizontal and vertical edges of the screen. It generates the image by drawing a set of random straight lines much in the same way one might move a pencil over a piece of paper to draw an image — drawing strokes from one point to another, one line at a time.

Introduction to Computer Graphics is a free, on-line textbook covering the fundamentals of computer graphics and computer graphics programming.