The document discusses various types of raster images and display technologies. Raster images represent pictures as a grid of pixels stored as numerical values. Grayscale images vary pixel depth to generate different colors. Color images use three values per pixel. Display technologies discussed include CRTs, LCDs, plasma displays, and other emissive and non-emissive displays. CRTs use electron guns and phosphors to generate images while LCDs use liquid crystals and polarized light.
Random scan displays and raster scan displaysSomya Bagai
Raster scan displays work by sweeping an electron beam across the screen in horizontal lines from top to bottom. As the beam moves, its intensity is turned on and off to illuminate pixels and form an image. The pixel values are stored in and retrieved from a refresh buffer or frame buffer. Random scan displays draw images using geometric primitives like points and lines based on mathematical equations, directing the electron beam only where needed. Raster scans have higher resolution but jagged lines, while random scans produce smooth lines but cannot display complex images. Both use a video controller and frame buffer in memory to control the display process.
Introduction to computer graphics part 1Ankit Garg
This document discusses computer graphics systems and their components. It describes video display devices like CRTs and how they work. Color is generated using techniques like beam penetration and shadow masks. Raster scan and random scan displays are covered. Input devices for graphics like mice, tablets, and gloves are also summarized. The document provides details on graphics hardware like frame buffers, refresh rates, and video controllers.
Raster scan systems with video controller and display processorhemanth kumar
The document describes how a raster scan display system works with a video controller. The video controller retrieves intensity values from a frame buffer area of memory and displays them on the screen line by line at a refresh rate of 50 times per second. It uses registers to store pixel coordinates and accesses the frame buffer to display the pixels. For color displays, it uses a lookup table to store RGB values and only needs to access the table index from the frame buffer for each pixel.
The document discusses computer graphics and various display technologies. It describes raster and vector display systems used in computer graphics. Raster systems store and display images as a grid of pixels using a process called scan conversion. Each pixel is stored in a frame buffer and refreshed rapidly to display the image. Vector systems draw images as geometric objects and lines. Common display technologies discussed include cathode ray tubes (CRT), liquid crystal displays (LCD), and plasma displays. Applications of computer graphics mentioned include computer-aided design (CAD), multimedia, visualization, and entertainment.
Raster scanning is a process used in television and computer graphics where an image is captured and reconstructed by systematically scanning across it in horizontal lines from top to bottom. Each line, called a scan line, is transmitted as an analog signal or divided into discrete pixels. Pixels are stored in a refresh buffer and then "painted" onto the screen one row at a time, with the beam returning to the left side during horizontal retrace and to the top left for vertical retrace between frames. Raster scanning provides realistic images but at the cost of lower resolution compared to random scanning systems.
This document provides an introduction to computer graphics. It defines computer graphics as the creation, storage, and manipulation of pictures and drawings using digital computers. Computer graphics is used across diverse fields such as engineering, medicine, education, entertainment, and more. The document discusses basic terms related to display devices such as pixels, resolution, color depth, and frame buffers. It also describes different types of display devices including raster scan displays, random scan displays, direct view storage tubes, flat panel displays, and stereoscopic displays. Applications of computer graphics such as design, image processing, animation, simulation, and medical imaging are also summarized.
Random scan displays and raster scan displaysSomya Bagai
Raster scan displays work by sweeping an electron beam across the screen in horizontal lines from top to bottom. As the beam moves, its intensity is turned on and off to illuminate pixels and form an image. The pixel values are stored in and retrieved from a refresh buffer or frame buffer. Random scan displays draw images using geometric primitives like points and lines based on mathematical equations, directing the electron beam only where needed. Raster scans have higher resolution but jagged lines, while random scans produce smooth lines but cannot display complex images. Both use a video controller and frame buffer in memory to control the display process.
Introduction to computer graphics part 1Ankit Garg
This document discusses computer graphics systems and their components. It describes video display devices like CRTs and how they work. Color is generated using techniques like beam penetration and shadow masks. Raster scan and random scan displays are covered. Input devices for graphics like mice, tablets, and gloves are also summarized. The document provides details on graphics hardware like frame buffers, refresh rates, and video controllers.
Raster scan systems with video controller and display processorhemanth kumar
The document describes how a raster scan display system works with a video controller. The video controller retrieves intensity values from a frame buffer area of memory and displays them on the screen line by line at a refresh rate of 50 times per second. It uses registers to store pixel coordinates and accesses the frame buffer to display the pixels. For color displays, it uses a lookup table to store RGB values and only needs to access the table index from the frame buffer for each pixel.
The document discusses computer graphics and various display technologies. It describes raster and vector display systems used in computer graphics. Raster systems store and display images as a grid of pixels using a process called scan conversion. Each pixel is stored in a frame buffer and refreshed rapidly to display the image. Vector systems draw images as geometric objects and lines. Common display technologies discussed include cathode ray tubes (CRT), liquid crystal displays (LCD), and plasma displays. Applications of computer graphics mentioned include computer-aided design (CAD), multimedia, visualization, and entertainment.
Raster scanning is a process used in television and computer graphics where an image is captured and reconstructed by systematically scanning across it in horizontal lines from top to bottom. Each line, called a scan line, is transmitted as an analog signal or divided into discrete pixels. Pixels are stored in a refresh buffer and then "painted" onto the screen one row at a time, with the beam returning to the left side during horizontal retrace and to the top left for vertical retrace between frames. Raster scanning provides realistic images but at the cost of lower resolution compared to random scanning systems.
This document provides an introduction to computer graphics. It defines computer graphics as the creation, storage, and manipulation of pictures and drawings using digital computers. Computer graphics is used across diverse fields such as engineering, medicine, education, entertainment, and more. The document discusses basic terms related to display devices such as pixels, resolution, color depth, and frame buffers. It also describes different types of display devices including raster scan displays, random scan displays, direct view storage tubes, flat panel displays, and stereoscopic displays. Applications of computer graphics such as design, image processing, animation, simulation, and medical imaging are also summarized.
Computer graphics involves the creation and manipulation of images on a computer using geometric objects and their representations. It has many applications including computer-aided design, presentation graphics, computer art, entertainment, education and training, scientific visualization, image processing, and graphical user interfaces. Graphics packages provide standard functions and tools for working with geometric objects and images.
This document provides an overview of computer graphics and its applications. It discusses various types of video display devices used in computer graphics like CRTs and flat panel displays. It describes how raster scan and random scan systems work and lists common input and output devices. The document outlines different chapters that will cover topics like line and curve generation algorithms, transformations, 3D viewing, surface detection, and modeling techniques. It provides examples of how computer graphics is used in fields like CAD, presentations, entertainment, education, visualization, image processing, and graphical user interfaces.
Computer graphics involves using computers to generate and manipulate visual and spatial data. It has various applications including computer-aided design, presentation graphics, education and training, visualization, image processing, entertainment, medical imaging, and graphical user interfaces. The key advantages of computer graphics are its ability to produce high quality visualizations and animations that can effectively communicate information.
Input devices are used to input information into a computer. Common input devices include keyboards, mice, graphic tablets, data gloves, light pens, and graphic cards. Keyboards are the most widely used input device for typing text. Mice are commonly used pointing devices that work by moving a ball or optical sensor. Graphic tablets allow users to hand draw images similar to drawing with paper and pencil. Data gloves are worn like normal gloves but have sensors to allow hand gestures to interact with virtual objects. Light pens can select objects on a display screen by pointing. Graphic cards are hardware that processes graphics and enables the display of images on a monitor.
This document is a lecture outline for an introduction to computer graphics course. It outlines the course information and administrative details, provides an overview of topics to be covered including graphics systems, techniques, operations and a mathematical review. It also defines computer graphics, discusses image processing and analysis, and explains why computer graphics is an important field due to advances in computing power, visualization, and interaction capabilities.
Raster scan displays have lower resolution than random scan displays because raster scan stores picture definition as intensity values along scan lines, while random scan stores pictures as line commands. Raster scan directs its electron beam from top to bottom across the entire screen one row at a time, making it less expensive than random scan which only draws required lines. However, random scan produces smoother lines and can provide more realistic displays through advanced techniques like shadows and hidden surfaces.
Computer graphics refers to creating and manipulating pictures and drawings using a computer. There are two main types: passive graphics which have no interaction and active graphics which allow two-way communication and interaction between the user and hardware. Computer graphics has many applications including user interfaces, scientific visualization, animation, computer aided design, presentation graphics, image processing, and education/training.
The document discusses cathode ray tubes (CRTs), which were the primary output devices in graphical systems and video monitors. CRTs display images using an electron beam that scans across phosphorescent screen coatings. There are two types of display methods: raster scan and random scan. Color CRTs use three electron guns and phosphors to produce red, green, and blue light, and require convergence calibration. CRTs were used in televisions, computer monitors, radar displays, and oscilloscopes. They can produce bright, high quality images but also have disadvantages like health hazards from radiation emission and potential overheating issues.
• Daroko blog (www.professionalbloggertricks.com)
• Presentation by Daroko blog, to see More tutorials more than this one here, Daroko blog has all tutorials related with IT course, simply visit the site by simply Entering the phrase Daroko blog (www.professionalbloggertricks.com) to search engines such as Google or yahoo!, learn some Blogging, affiliate marketing ,and ways of making Money with the computer graphic Applications(it is useless to learn all these tutorials when you can apply them as a student you know),also learn where you can apply all IT skills in a real Business Environment after learning Graphics another computer realate courses.ly
• Be practically real, not just academic reader
This document discusses various input devices used for computer graphics workstations, including keyboards, mice, trackballs, spaceballs, joysticks, digitizers, image scanners, touch panels, light pens, and voice systems. These input devices allow users to input data, position screen cursors, select coordinates, and initiate graphics operations through mechanisms like buttons, wheels, sensors that detect motion and pressure, and voice recognition. Common input devices include mice, keyboards, graphics tablets, and touchscreens, while others like data gloves and spaceballs provide additional degrees of freedom for spatial input and manipulation in areas like virtual reality and 3D modeling.
A graphics monitor is a display that can show graphics in addition to text. Graphics monitors are used in applications like air traffic control, medical imaging, and CAD. A workstation is a powerful computer optimized for visualization and manipulation of complex data like 3D modeling, simulation, and image rendering. Workstations have specifications like 64MB or more of RAM, high-resolution graphics screens, large displays, and built-in network support. They are used for graphics-intensive applications like 3D design, video editing, and CAD. A server handles data requests from other computers on a network and hosts applications, while a workstation is a personal computer used for graphics applications and intensive programs by professional users.
This document discusses the process of computer animation. It begins by defining computer animation and listing some common applications like video games, cartoons, and mobile phones. It then outlines the main steps for designing an animation sequence, which include storyboard layout, object definitions, key frame specifications, and generating in-between frames. Key frames define the starting and ending points of movements, while in-betweens create the illusion of smooth motion between key frames. Raster animation and general animation functions are also briefly discussed.
a spline is a flexible strip used to produce a smooth curve through a designated set of points.
Polynomial sections are fitted so that the curve passes through each control point, Resulting curve is said to interpolate the set of control points.
Raster scan systems use a video controller to refresh the screen by accessing pixels stored in a frame buffer in memory. The video controller uses two registers to iterate through each pixel location, retrieving the pixel value and using it to set the intensity of the CRT beam. It draws one scan line at a time from top to bottom until the entire screen is refreshed at a rate of 60 frames per second. Display processors can offload graphics processing tasks from the CPU by performing operations like scan conversion and generating lines and color areas to draw objects in the frame buffer.
Scan conversion is the process of representing continuous graphics objects as discrete pixels. It involves converting geometric primitives like lines and circles, defined by parameters, into a set of pixels that make up the primitive in an image. This involves mapping real-valued coordinates to integer pixel coordinates. One approach is to take the floor of the x and y values, while another is to take the floor of x+0.5 and y+0.5 to center the coordinate system at the pixel grid.
The document summarizes raster scan and random scan displays. Raster scan displays use an electron beam that sweeps across the screen from top to bottom to generate pixels based on values stored in a refresh buffer. Random scan displays directly draw images using an electron beam without a fixed pattern, storing only line drawing instructions. The key differences are that raster scan is used for realistic images due to storing intensity values while random scan has higher resolution but is limited to line drawings. Both use a cathode ray tube containing an electron gun, deflection coils, and phosphor screen.
The document discusses different types of video display devices, focusing on cathode ray tubes (CRTs). It describes how CRTs work using an electron gun, deflection plates, and phosphor-coated screen to produce images. Color CRT monitors are also covered, explaining how they produce color using either beam penetration or shadow mask methods. Other display types mentioned include direct view storage tubes, flat panel displays, and their key differences from CRTs.
This slide contain description about the line, circle and ellipse drawing algorithm in computer graphics. It also deals with the filled area primitive.
This document provides an overview of graphics systems including video display devices, input devices, and raster-scan systems. It describes cathode ray tube monitors as the primary output device and discusses raster-scan and random-scan display principles. Color CRT monitors use color phosphors and shadow masks or electron guns to produce color. Flat panel displays like plasma panels and LCDs are also covered. Common input devices include mice, keyboards, tablets, and touchscreens. Raster-scan systems use a frame buffer in video memory that is refreshed by a video controller to display an image on a monitor.
Computer graphics involves the creation and manipulation of images on a computer using geometric objects and their representations. It has many applications including computer-aided design, presentation graphics, computer art, entertainment, education and training, scientific visualization, image processing, and graphical user interfaces. Graphics packages provide standard functions and tools for working with geometric objects and images.
This document provides an overview of computer graphics and its applications. It discusses various types of video display devices used in computer graphics like CRTs and flat panel displays. It describes how raster scan and random scan systems work and lists common input and output devices. The document outlines different chapters that will cover topics like line and curve generation algorithms, transformations, 3D viewing, surface detection, and modeling techniques. It provides examples of how computer graphics is used in fields like CAD, presentations, entertainment, education, visualization, image processing, and graphical user interfaces.
Computer graphics involves using computers to generate and manipulate visual and spatial data. It has various applications including computer-aided design, presentation graphics, education and training, visualization, image processing, entertainment, medical imaging, and graphical user interfaces. The key advantages of computer graphics are its ability to produce high quality visualizations and animations that can effectively communicate information.
Input devices are used to input information into a computer. Common input devices include keyboards, mice, graphic tablets, data gloves, light pens, and graphic cards. Keyboards are the most widely used input device for typing text. Mice are commonly used pointing devices that work by moving a ball or optical sensor. Graphic tablets allow users to hand draw images similar to drawing with paper and pencil. Data gloves are worn like normal gloves but have sensors to allow hand gestures to interact with virtual objects. Light pens can select objects on a display screen by pointing. Graphic cards are hardware that processes graphics and enables the display of images on a monitor.
This document is a lecture outline for an introduction to computer graphics course. It outlines the course information and administrative details, provides an overview of topics to be covered including graphics systems, techniques, operations and a mathematical review. It also defines computer graphics, discusses image processing and analysis, and explains why computer graphics is an important field due to advances in computing power, visualization, and interaction capabilities.
Raster scan displays have lower resolution than random scan displays because raster scan stores picture definition as intensity values along scan lines, while random scan stores pictures as line commands. Raster scan directs its electron beam from top to bottom across the entire screen one row at a time, making it less expensive than random scan which only draws required lines. However, random scan produces smoother lines and can provide more realistic displays through advanced techniques like shadows and hidden surfaces.
Computer graphics refers to creating and manipulating pictures and drawings using a computer. There are two main types: passive graphics which have no interaction and active graphics which allow two-way communication and interaction between the user and hardware. Computer graphics has many applications including user interfaces, scientific visualization, animation, computer aided design, presentation graphics, image processing, and education/training.
The document discusses cathode ray tubes (CRTs), which were the primary output devices in graphical systems and video monitors. CRTs display images using an electron beam that scans across phosphorescent screen coatings. There are two types of display methods: raster scan and random scan. Color CRTs use three electron guns and phosphors to produce red, green, and blue light, and require convergence calibration. CRTs were used in televisions, computer monitors, radar displays, and oscilloscopes. They can produce bright, high quality images but also have disadvantages like health hazards from radiation emission and potential overheating issues.
• Daroko blog (www.professionalbloggertricks.com)
• Presentation by Daroko blog, to see More tutorials more than this one here, Daroko blog has all tutorials related with IT course, simply visit the site by simply Entering the phrase Daroko blog (www.professionalbloggertricks.com) to search engines such as Google or yahoo!, learn some Blogging, affiliate marketing ,and ways of making Money with the computer graphic Applications(it is useless to learn all these tutorials when you can apply them as a student you know),also learn where you can apply all IT skills in a real Business Environment after learning Graphics another computer realate courses.ly
• Be practically real, not just academic reader
This document discusses various input devices used for computer graphics workstations, including keyboards, mice, trackballs, spaceballs, joysticks, digitizers, image scanners, touch panels, light pens, and voice systems. These input devices allow users to input data, position screen cursors, select coordinates, and initiate graphics operations through mechanisms like buttons, wheels, sensors that detect motion and pressure, and voice recognition. Common input devices include mice, keyboards, graphics tablets, and touchscreens, while others like data gloves and spaceballs provide additional degrees of freedom for spatial input and manipulation in areas like virtual reality and 3D modeling.
A graphics monitor is a display that can show graphics in addition to text. Graphics monitors are used in applications like air traffic control, medical imaging, and CAD. A workstation is a powerful computer optimized for visualization and manipulation of complex data like 3D modeling, simulation, and image rendering. Workstations have specifications like 64MB or more of RAM, high-resolution graphics screens, large displays, and built-in network support. They are used for graphics-intensive applications like 3D design, video editing, and CAD. A server handles data requests from other computers on a network and hosts applications, while a workstation is a personal computer used for graphics applications and intensive programs by professional users.
This document discusses the process of computer animation. It begins by defining computer animation and listing some common applications like video games, cartoons, and mobile phones. It then outlines the main steps for designing an animation sequence, which include storyboard layout, object definitions, key frame specifications, and generating in-between frames. Key frames define the starting and ending points of movements, while in-betweens create the illusion of smooth motion between key frames. Raster animation and general animation functions are also briefly discussed.
a spline is a flexible strip used to produce a smooth curve through a designated set of points.
Polynomial sections are fitted so that the curve passes through each control point, Resulting curve is said to interpolate the set of control points.
Raster scan systems use a video controller to refresh the screen by accessing pixels stored in a frame buffer in memory. The video controller uses two registers to iterate through each pixel location, retrieving the pixel value and using it to set the intensity of the CRT beam. It draws one scan line at a time from top to bottom until the entire screen is refreshed at a rate of 60 frames per second. Display processors can offload graphics processing tasks from the CPU by performing operations like scan conversion and generating lines and color areas to draw objects in the frame buffer.
Scan conversion is the process of representing continuous graphics objects as discrete pixels. It involves converting geometric primitives like lines and circles, defined by parameters, into a set of pixels that make up the primitive in an image. This involves mapping real-valued coordinates to integer pixel coordinates. One approach is to take the floor of the x and y values, while another is to take the floor of x+0.5 and y+0.5 to center the coordinate system at the pixel grid.
The document summarizes raster scan and random scan displays. Raster scan displays use an electron beam that sweeps across the screen from top to bottom to generate pixels based on values stored in a refresh buffer. Random scan displays directly draw images using an electron beam without a fixed pattern, storing only line drawing instructions. The key differences are that raster scan is used for realistic images due to storing intensity values while random scan has higher resolution but is limited to line drawings. Both use a cathode ray tube containing an electron gun, deflection coils, and phosphor screen.
The document discusses different types of video display devices, focusing on cathode ray tubes (CRTs). It describes how CRTs work using an electron gun, deflection plates, and phosphor-coated screen to produce images. Color CRT monitors are also covered, explaining how they produce color using either beam penetration or shadow mask methods. Other display types mentioned include direct view storage tubes, flat panel displays, and their key differences from CRTs.
This slide contain description about the line, circle and ellipse drawing algorithm in computer graphics. It also deals with the filled area primitive.
This document provides an overview of graphics systems including video display devices, input devices, and raster-scan systems. It describes cathode ray tube monitors as the primary output device and discusses raster-scan and random-scan display principles. Color CRT monitors use color phosphors and shadow masks or electron guns to produce color. Flat panel displays like plasma panels and LCDs are also covered. Common input devices include mice, keyboards, tablets, and touchscreens. Raster-scan systems use a frame buffer in video memory that is refreshed by a video controller to display an image on a monitor.
This document summarizes computer graphics and display devices. It discusses that computer graphics involves displaying and manipulating images and data using a computer. A typical graphics system includes a host computer, display devices like monitors, and input devices like keyboards and mice. Common applications of computer graphics include GUIs, charts, CAD/CAM, maps, multimedia, and more. Display technologies discussed include CRT monitors, LCD panels, and other devices. Key aspects of CRT monitors like refresh rate, resolution, and bandwidth are also summarized.
This document provides information about different types of display devices used in computer graphics. It discusses cathode ray tubes (CRTs) which produce images using an electron beam striking a phosphorescent screen. CRTs are bulky and electromagnetic fields may pose health risks. Raster scan displays redraw images by sweeping an electron beam across the screen in lines. Color CRTs use phosphors and shadow masks to produce colors. Flat panel displays like liquid crystal displays are thinner alternatives to CRTs.
This PPT gives detailed information about Computer Graphics, Raster Scan System, Random Scan System, CRT Display, Color CRT Monitors, Input and Output Devices
This document summarizes different types of display devices, including cathode ray tubes (CRTs), raster scan displays, random scan displays, liquid crystal displays (LCDs), and light emitting diodes (LEDs). It describes the basic components and functioning of CRTs, including electron guns, phosphor coatings, and deflection coils. It compares raster and random scan displays, noting that raster displays are better for realistic images while random scans are suited for line drawings. LCDs use polarized light passing through liquid crystals to turn pixels on and off. LED displays use semiconductors to emit light when forward biased, and have advantages over traditional light sources like lower energy use and longer lifetimes.
The document discusses various display devices used for visual presentation of information. It describes cathode ray tubes (CRT), which use electron guns and phosphorescent coatings to produce images. Raster scan displays refresh images by sweeping an electron beam across the screen in rows, while random scan displays draw individual lines. Liquid crystal displays (LCD) use polarized light passing through liquid crystals. Light emitting diodes (LED) also emit light when electrically biased and are used in displays and lighting due to their low energy use and long lifetime. The document provides details on the components and functioning of CRTs and explains the differences between raster and random scan displays.
The document discusses different types of graphics display systems including raster scan displays, random scan displays, and flat panel displays. It describes the key components of cathode ray tube (CRT) displays such as the electron gun and phosphor screen and how they generate images. It also covers color reproduction methods for CRTs like beam penetration and three color guns.
The document summarizes video display devices, specifically cathode ray tubes (CRTs). It describes the basic design of CRTs including the electron gun, phosphor coating, and refresh process. CRTs use an electron beam directed by deflection systems to illuminate spots on the screen in a raster pattern, maintained by refreshing the screen rapidly. Color CRTs employ different color phosphors and methods like beam penetration or shadow masks to combine colors. Random scan displays draw images as lines rather than pixels.
The document provides an overview of computer graphics systems. It discusses different types of display devices including refresh cathode-ray tubes, raster-scan displays, random-scan displays, color CRT monitors, and flat panel displays. It also covers basics of raster graphics systems and random scan systems, including components like the video controller, display processor, and frame buffer. Input devices for graphics systems such as the keyboard, mouse, and digitizer are also mentioned.
CG03 Random Raster Scan displays and Color CRTs.ppsxjyoti_lakhani
The document discusses different types of graphics displays. It describes raster-scan displays, which use an electron beam that sweeps across the screen from top to bottom to display an image. Picture definition is stored in a frame buffer. It also describes random-scan displays, which direct the electron beam only where lines need to be drawn. Color CRT monitors use phosphors and a shadow mask to display color. Flat panel displays like plasma panels, thin-film electroluminescent displays, and liquid crystal displays provide thinner alternatives to CRTs.
The document describes various types of computer display devices and their characteristics. It discusses raster and random scan displays, CRT monitors, color CRT technologies including beam penetration and shadow mask methods, and other display types such as direct view storage tubes. Input devices are also covered, including keyboards, mice, digitizers, and touch screens.
This document provides an overview of video display devices and color graphics technologies. It discusses raster scan displays, which refresh the screen by sweeping the electron beam across rows of pixels stored in a frame buffer. Random scan displays direct the electron beam only where needed to draw lines, allowing higher resolution but not realistic images. Color CRT monitors use shadow mask or beam penetration methods, with the former allowing a wider range of colors by exciting red, green, and blue phosphor dots. Flat panel displays are thinner than CRTs and being used in more portable applications.
Computer graphics refers to creating, manipulating, and displaying visual images and animations using computers. There are two main types: interactive and non-interactive. Computer graphics has many applications including graphical user interfaces, plotting graphs and charts, simulations, entertainment, CAD/CAM, medicine, history, art, and cartography. Raster and vector graphics are the two main types of computer graphics representations. Raster uses a grid of pixels while vector uses mathematical formulas to define shapes.
This document discusses computer graphics hardware concepts related to video display devices and input/output devices. It describes the components and operation of cathode ray tube (CRT) displays, including the electron gun, accelerating anode, focusing system, deflection system, and phosphor screen. It also covers raster scan displays, random scan displays, color CRT monitors, and flat panel displays such as plasma panels, thin-film electroluminescent displays, and liquid crystal displays (LCDs). Input devices discussed include keyboards, mice, trackballs, joysticks, digitizers, and image scanners. Output devices covered are printers, including dot matrix, laser, inkjet, and bubble jet printers.
This document discusses computer graphics systems and their components. It describes common display devices like CRT monitors and how they work. It explains color generation techniques in monitors using beam penetration or shadow mask methods. Input devices for graphics like mice, tablets, and joysticks are also covered. The document provides details on frame buffers, resolution, refresh rates and how raster scan displays redraw images.
This document provides an overview of graphics display systems. It discusses the basic components and operation of cathode ray tube (CRT) displays, including the electron gun, focusing and deflection systems. It describes the refresh process of raster-scan CRTs and how random-scan CRTs work. Color CRT monitors are discussed, specifically the beam penetration and shadow mask methods. Key characteristics like resolution, persistence and aspect ratio are also summarized.
The document presents information on different types of display devices including CRT, LCD, plasma display, and LED displays. It discusses the key components, working principles, and properties of CRT and flat panel displays such as LCD, plasma, and LED displays. Advantages and disadvantages of different display technologies are also highlighted.
This document discusses different types of CRT display systems. It describes Direct View Storage Tubes (DVST) which store images using a long persistence phosphor but cannot be updated quickly. Random scan/calligraphic displays draw lines in arbitrary order but must be refreshed at 30 Hz. Raster scan displays store images as a matrix of pixels in a refresh buffer and draw the entire screen sequentially one line at a time, allowing for animation and faster updating than DVST systems.
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Computer graphics
1. Raster Images
Picture is made up of small cells
called pixels
Stored in computer memory as
array of numeral values called pixel
map or bitmap
Raster images are created suing
Hand designed images
Computed images (Mathematical
model of a scene)
Scanned images (support scaling)
2. Gray scale raster images
Pixel dept (memory required /pixel)
n-bit memory generates 2n
color values
Effect of pixel dept
Quality of image
Avoid color banding
Size of image
5. Display technologies
Cathode Ray Tubes
(CRTs)
Most common display
device today.
Evacuated glass
bottle
Extremely high
voltage
Heating element
(filament)
Electrons pulled
towards
anode focusing
cylinder
Vertical and
horizontal deflection
plates
Beam strikes
phosphor coating on
front of tube
7. Electron gun Contains a filament that, when heated, emits a stream of
electrons
Electrons are focused with an electromagnet into a sharp
beam and directed to a specific point of the face of the
picture tube
The front surface of the picture tube is coated with small
phosphor dots
When the beam hits a phosphor dot it glows with a brightness
proportional to the strength of the beam and how long it is hit
8. CRT characteristics
What’s the largest (diagonal) CRT you’ve
seen?
Why is that the largest?
Evacuated tube == massive glass
Symmetrical electron paths (corners vs. center)
How might one measure CRT capabilities?
Size of tube
Brightness of phosphers vs. darkness of tube
Speed of electron gun
Width of electron beam
Pixels?
9. Random Scan Display (Vector
Displays) Early computer displays, Control X,Y with
vertical/horizontal plate voltage
Often used intensity as Z (close things were
brighter)
Name two disadvantages
Just does wireframe
Complex scenes cause visible flicker
12. Vector Displays
How to generate an image using vectors
A line is represented by endpoints (10,10) to (90,90)
The points along the line are computed using a line
equation
y = mx + b
If you want the image larger, no
problem…
13. Raster Displays
Raster: A rectangular array of points or dots
Pixel: One dot or picture element of the
raster
Scan line: A row of pixels
14. Raster Displays
Black and white television: A fixed scan pattern: left to
right, top to bottom
As beam sweeps across entire face of CRT, beam
intensity changes to reflect brightness
Must synchronize
Your program makes decisions about the intensity signal
at the pace of the CPU…
The screen is “painted” at the pace of the electron gun
scanning the raster
Solution: special memory to buffer image with scan-out
synchronous to the raster. We call this the frame buffer.
16. Line Generation on Raster Display
How to generate a line using rasters
A line is represented by assigning some pixels a
value of 1
The entire line is specified by the pixel values
What do we do to make image larger?
17. Phosphers
Fluorescence
Light emitted while the phosphor is being struck
by electrons()
Phosphorescence
Light emitted once the electron beam is
removed
Persistence
The time from the removal of the excitation to
the moment when phosphorescence has
decayed to 10% of the initial light output
18. Refresh
Frame must be “refreshed” to draw new images
As new pixels are struck by electron beam,
others are decaying
Electron beam must hit all pixels frequently to
eliminate flicker
Critical fusion frequency
Typically 60 times/sec
Varies with intensity, individuals, phospher
persistence, lighting...
20. Color CRT
Color CRTs are much more complicated
Requires manufacturing very precise geometry
Uses a pattern of color phosphors on the screen:
Why red, green, and blue phosphors?
Delta electron gun arrangement In-line electron gun arrangement
21. Color CRT
Color CRTs have
Three electron guns
Beam penetration and shadow mask methods
A metal shadow mask to differentiate the beams
23. CRTs – A Review
CRT technology hasn’t changed much in 50 years
Early television technology
high resolution
requires synchronization between video signal and electron
beam vertical sync pulse
Early computer displays
avoided synchronization using ‘vector’ algorithm
flicker and refresh were problematic
24. CRTs – A Review
Raster Displays (early 70s)
like television, scan all pixels in regular pattern
use frame buffer (video RAM) to eliminate sync
problems
RAM
¼ MB (256 KB) cost $2 million in 1971
Do some math…
- 1280 x 1024 screen resolution = 1,310,720
pixels
- Monochrome color (binary) requires 160 KB
- High resolution color requires 5.2 MB
25. Liquid Crystal Displays (LCDs)
LCDs: organic molecules, naturally in crystalline state, that liquefy
when excited by heat or Electric field
Crystalline state twists polarized light 90º.
26. Polarizer
A wire-grid polarizer converts an unpolarized beam
into one with a single linear polarization. Red arrows
depict the electric field vector.
30. Display Technology: Plasma
Plasma display panels
Similar in principle to
fluorescent light tubes
Small gas-filled capsules
are excited by electric field,
emits UV light
UV excites phosphor
Phosphor relaxes, emits
some other color
32. Thin Film
Electroluminescent Display
Same as plasma display
Has phosphor coating instead of gas
High voltage applied on phosphor
Require more power
Good colors are hard to generate
Another emissive display is LED
33. Direct View Storage Tube
(DVST) Instead of refreshing screen, it Keeps information inside CRT
Picture information is stored as charge distribution behind the phosphorous
screen
Two electron guns are used in DVST, the primary gun and flood gun
Primary helps is storing picture patterns and flood gun maintain picture
display
No refresh requires, can display complex high resolution picture without flicker
Usually doesn’t display colors
Part of a picture can’t be refreshed (redrawn)
Erasing old picture and redrawing modified picture could take seconds
No replaced by raster displays
34. Raster Scan System
Special purpose processor called video/display
controller used to control operations of display
Video controller accesses frame buffer from
system memory
Some systems also use graphics/display processor
to relieve CPU of core graphic activities
Frame buffer locations and corresponding screen
positions are referenced in Cartesian coordinates
Coordinate origin is decided
35. Raster Scan System
Architedure of a simple raster graphics system.
Architecture of a raster system with a fixed portion of the system
memory reserved for the frame buffer.
36. Raster Scan System
intensity
Basic video-controller refresh operations
The origin of the coordinate
system for identifying screen
positions is usually specified
in the lower-left corner.
37. Raster Scan System
High quality system provides two frame buffers
Video controller also transform screen
Some video controllers use lookup tables (color
palets) and frame buffer values are indexed into
it to retrieve intensities
Some controllers allows mixing frame buffer’s
image with camera picture
39. Raster Scan Display
ProcessorDisplay processors scan convert, lines, curves and other
objects into intensity values
Characters are specified by rectangular grid or curved lines
Character grid can be 5 by 7 or 9 by 12 or more in high quality displays
Character grid is superimposed and character curves are scan converted
40. Raster Scan Display
Processor Digitize/scan-conversion picture definition provided by
application program
Display processor also performs additional tasks e.g. changing line
styles, coloring areas, transformation on objects etc
Efforts are made to shorten frame buffer
One way is to store intensity information as link list and apply run-
length encoding
Similar method applies when intensities change linearly
Short runs can increase storage requirements
Short runs bring difficulty in processing
Another approach encode raster as set of rectangular areas,
called cell encoding
42. Random Scan System
Display processor also called display processing unit or
graphics controller
Application program along with graphic package
stored in memory
Graphics commands of application are transformed by
graphic package into display file, stored in memory
Display processor goes through each line in display file in
a refresh cycle
Lines are specified by end points
Scene is drawn one line at a time and deflection
voltages are directed to fill region b/w end points
43. Hard Copy Devices
Purpose is to put our graphics/picture on
paper
Quality of pictures: Dots/inch also known
as resolution
High quality printing: Adjacent dots
overlaps
Two type of printers: Impact and non-
impact
Impact: press formed character faces
against ink ribbon
Non-impact: Use laser technique, inkjet
spay, xerographic process, electrostatic
or electro-thermal methods
44. Hard Copy Devices
Dot-matrix Printer
Impact printer
Dot-matrix head with rectangular array of
protruding wire pins
Number of pins depends on quality of printer
Character face or graphic patterns drawn by
retracting certain pins
Single column vs multi column printing head
45. Hard Copy Devices
Laser Printer
Have photoelectric,
e.g. selenium, coated
drum
Graphics are drawn by
creating charge
distribution on drum
using laser beam
Toner is applied to the
drum
Toner then applied to
paper to draw graphics
Xerographic Process
46. Hard Copy Devices
Ink-jet Printer
Paper wrapped on a drum
Ink is squirted horizontally across the length of paper
Ink-stream is deflected by electric field
Produce dot-matrix patterns
Three types: Thermal ink-jet, Piezoelectric ink-jet and continuous ink-jet
Thermal inkjet send current through heating element in heating
chamber and make steam explosion
Current send to piezoelectric material in ink-filled chamber which
changes shape & size and produce pressure
High-pressure pumps direct ink through a gunbody, microscopic nozzle,
piezoelectric crystal produce accoustic waves which breaks ink stream
into droplets at continuous intervals
Heating element contract on cooling and suck further ink from reserviors
47. Hard Copy Devices
Pen Plotter
A plotter is a vector graphics printing device to print
graphical plots
Move pen across the piece of paper
Can draw complex line art and text but very slowly
Can draw filled regions by complex closed lines
Printer control languages created to send more detailed
command for text
Paper placed over a roller which moves paper back &
forth for x motion and pen moved back & forth for y
motion
Fast computing, inexpensive memory and quality raster
graphics with laser and inkjet have replaced pen-plotters
48. Hard Copy Devices
Electrostatic Device
Place negative charge on the length of paper one
row at a time
Paper is then exposed to toner
Toner is positively charged
Negative and positive charge produce adhesion
49. Hard Copy Devices
Electro-thermal Device
Heat sensitive coated thermal paper
Apply selective heating
Produce output patterns using dotmatrix printing
head
Image is produced in the area where it is heated
Two color direct thermal printer produce black and
red color images when heated on two different
temperatures
50. Input Devices
Keyboard
Used for entering text
Extra features: screen coordinates, object selection,
menu selection and graphic functions
Function keys used to activate frequently used
operations
Cursor control keys used to relocate screen cursor
Can accompany track ball or joy stick
Additional numeric keyboard used for fast entry of
numeric data
Specialized application: buttons, switches and dials
51. Input Devices
Mouse
Another major input device
Small handheld box used to reposition screen cursor
Movement is recorded using wheel or roller in
bottom
Movement is also detected with optical sensor with
special mouse pad having horizontal and vertical
line grid
Not fixed, Used for relative changes in screen cursor
Also accompany two or three buttons to activate
certain function
Also Z mouse for 3D application
52. Input Devices
Track ball and space ball
A ball with potentiometer, produce screen
movements
Unlike track ball, the Space ball doesn’t actually
move
Strain gauges measure the amount of pressure and
the direction of pressure
Used for three dimensional positioning in virtual
reality, animation and CAD
53. Input Devices
Joy Stick
A small vertical lever which steers screen cursor
Some record physical movement of the stick while
others record only pressure on the stick
In first movement and direction and in second
pressure and direction is gauged (strain gauge)
Potentiometer is used
Might be mounted on the keyboard
Can also use one or more buttons
54. Input Devices
Image scanner
Pictures, graphs, charts, text etc can be used as bitmap in
computer memory
They are stored as color or grayscale grades
Purpose is to process image objects
Transform objects
Crop different areas (Picture editing)
Image processing
Extract text
Available in variety of sizes, from hand held to huge
55. Input Devices
Touch Panels
Select processing options, displayed
objects or screen positions with touch of
screen
Touch inputs are devised with optical,
electrical or acoustic methods
In optical method, infrared LEDs are fixed
along vertical and horizontal edges of the
frame (light detectors on opposite sides)
Detector detects which horiz and vert
beams are interrupted
In case of closed LEDs, Avg is taken when
two or more beams are interrupted
56. Input Devices
Touch Panel (continued…)
Should match the color and contour of system
In electrical method, two transparent plats, one
conductor and second resister, placed on small
distance
Both plates touches when pressure is applied
Voltage drop in resister plates is recorded as screen
coordinates
In acoustic method, acoustic waves are generated
across horiz and vertical directions
Interruption causes reflection of waves
Time interval is calculated to find screen
coordinates
57. Input Devices
Light Pen
Record screen location when electron been passes
to that point
Don’t detect environment light
Can’t detect black spots
Application must keep non-zero intensity for black
screen position
Few other disadvantages
58. Voice System
System is trained for a particular operator
Frequencies are recorded for different words for the
operator
System record word and operation performed on
those words
On use, operator voice is searched in dictionary
and operation for that word is performed
User don’t have to switch among devices
62. Human vision system
Human eye is a spherical camera with 20mm focal length
Lens focus the image on retina
Iris control the amount of light passing through pupil
Each eye is populated unevenly with 100m receptor cells
Near the fovea dense concentration of color receptor called
cons
Density of black & white receptors, called rods, increases
away from the center and cons decreases
Three different types of cons (with different chemical
properties) are sensitive to light of three different wavelengths
human is tri-chromate
63. Color model
Provide mechanism for encoding of color in
visible spectrum
Mathematical model for describing colors as
tuple of numbers
Numbers are usually three or four
Gives precise definition of how components are
interpreted
Usually define some primary colors
65. CMY Color Model
Cyan, Magenta, Yellow
Subtractive color scheme (Subtract from
white, transparent inks)
Colors which are not absorbed, determine
color
Cyan absorb red, magenta absorb green
and yellow absorbs blue
White(0,0,0): No component of light is
absorbed
Black(255,255,255): ???
66. CMYK Color Model
Cyan, Magenta, Yellow, Key
(Black)
Same as CMY
Black is added to improve
reproduction of some dark
colors
To save money on ink, and to
produce deeper black tones,
unsaturated and dark colors are
produced by substituting black
ink for the combination of cyan,
magenta and yellow
67. HSI or HSV Color Model
Hue, Saturation,
Intensity or Value
68. HSI or HSV Color Model
Separate Intensity from chromacy – Hue and
Saturation
Hexagon or hexacon is formed by projecting
RGB color cube along its major diagonal
Vertical intensity axes
H is defined angle between 0 and 2Π relative
to a-axes (0 angle mean pure red)
S is defined as color purity (1 pure i.e.
saturated and 0 for unsaturated i.e. some
shades of gray)
Convenient for graphics designers, provide
direct control over hue and brightness
69. 2D Trasformation
Changes in the object orientation, size and shape
is accomplished by 2D transformation
Basic transformations
Translation
Rotation and
Scaling
70. 2D Trasformation
Translation
Object is moved along a line path from one
coordination to another
It’s a rigid body transformation (no deformation)
(x, y) Original coordinate location
(tx, ty) translation distance, also called the translation
vector or shift vector
(x’
,y’
) new coordinate location
The most common type of graphics monitor employing a CRT is the raster-scan display, based on television technology…In a raster-scan system, the electron
beam is swept across the screen, one row at a time from top to bottom……Picture definition is stored in a memory area called the refresh buffer or frame buffer
Black and white system…….single color images exact black or exact white….per pixel I byte(8 bit) size…….
The primary output device in a graphic system is a video display monitors…….. The displaying operation( graphics or images on this display screen )is done through cathode ray tube…..
Persistence is defined as the time it takes the emitted light from the screen to decay to one-tenth of its original intensity.
Details about the basic operation of cathode rays tube……
Firstly the beam of electron is emitted by electron gun and passes it through focusing system and deflection system…..the magnetic deflection coils and focusing system divert the electron beam towards their exact position on the phosphorus coated-screen…. The phosphorus then emits a small spot of light at each position which are coming from electron beam…..
The primary components of an electron gun in a CRT are the heated metal cathode and a control grid ….. Intensity of the electron beam is controlled by setting voltage levels on the control grid, which is a metal cylinder that fits over the cathode……Since the amount of light emitted by the phosphor coating depends on the number of electrons striking the screen, we control the brightness of a display by varying the voltage on the control grid……..
The focusing system in a CRT is needed to force the electron beam to converge into a small spot as it strikes the phosphor. Otherwise, the electrons would repel each other.
Intensity of the electron beam is controlled by setting voltage levels on the control grid, which is a metal cylinder that fits over the cathode…..
Random scan monitors draw a picturePicture definition is now stored as a set of line drawing commands in an area of memory r efered to as the refresh display file one line at a time and for this reason are also referred to as vector displays (or stroke-writing or calligraphic displays).
Electronic devices…….for video display devices ……first picture once created second is already create ….and here is memory for pixel…….. Every display application have memory to allocate the picture ……then it take picture………synchronization in graphics, here make a picture and utilize it as a video so memory (buffer)free for other picture…..so our video is electromechanical device……
Double buffer image……..
To increase the size of raster image ……. Repeat all row and column twice……algorithm are used for this…………
In video display elctron come and hit the screen and generate a pixel picture and ……..frame for each picture………
In color picture Every pixel composed on three pixel(RGB)…..so every (RGB) have intensity and participate with different proportion…………..now our electron gun also composed on three waves………..two way arrangement for color pixel arrangement..