UNIT 2

• Computer graphics describes any use of computers to create and manipulate images
• Graphics can be two- or three-dimensional; images can be completely synthetic or produced by manipulating photographs
• Modeling deals with the mathematical specification of shape and appearance properties that can be stored on the computer
• Rendering deals with the creation of shaded images from 3D computer models
• Animation is a technique to create an illusion of motion through sequences of images
• User interaction deals with the interface between input devices such as mice and tablets, application, feedback to the user in imagery, and other sensory feedback
• Virtual reality attempts to immerse the user into a 3D virtual world, often requiring stereo graphics and response to head motion
• Visualization attempts to give users insight into complex information via visual display
• Image processing deals with the manipulation of 2D images and is used in both graphics and vision fields
• 3D scanning uses range-finding technology to create measured 3D models
• Computational photography uses computer graphics, computer vision, and image processing methods to capture objects, scenes, and environments photographically
• Visual computing deals with the acquisition, analysis, and synthesis of visual data through computer resources
• Visual computing encompasses computer science, mathematics, physics, and cognitive sciences
• Visual computing includes computer graphics, image processing, visualization, computer vision, virtual and augmented reality, video processing, pattern recognition, human-computer interaction, machine learning, and digital libraries
• Visual computing aims to let us control and interact with activities through the manipulation of visual images
• Video games increasingly use sophisticated 3D models and rendering algorithms
• Cartoons are often rendered directly from 3D models
• Visual effects use various computer graphics technology in modern films for digital compositing, 3D modeling, animation, and creating synthetic environments and characters
• Animated films use techniques similar to visual effects but may not aim for realistic images
• CAD/CAM stands for computer-aided design and computer-aided manufacturing, using computer technology to design parts and products virtually
• Simulation can be thought of as accurate video gaming and is useful for training in safety-critical domains and scenario training
• Medical imaging creates meaningful images of scanned patient data using computer graphics
• Information visualization creates images of data that may not have a natural visual depiction
• Most computer graphics images are presented on raster displays, showing images as rectangular arrays of pixels
• Raster images store pixel values for each pixel, usually as three numbers for red, green, and blue
• Vector images describe shapes with no reference to a pixel grid, allowing resolution independence and display on high-resolution devices
• Raster devices can be categorized into output, display (transmissive and emissive), hardcopy (binary and continuous tone), and input (2D array sensor and 1D array sensor)
• Displays are based on fixed arrays of pixels, separated into emissive displays (e.g., LED) and transmissive displays (e.g., LCD)
• LED displays use LEDs to emit light with varying intensities of red, green, and blue to create colors
• LCDs use liquid crystals to vary the amount of light passing through pixels
• Printers are raster devices like displays, with ink-jet printers forming raster images by scanning and thermal dye transfer printers allowing varying amounts of dye deposition
• Printer resolution is described in terms of pixel density, with ink-jet printers having a resolution of dots per inch (dpi) and thermal dye transfer printers having a resolution of pixels per inch (ppi)
• Raster input devices like cameras and scanners measure light values for each pixel, with cameras using CCDs or CMOS sensors and scanners using a 1D array to sweep across the page being scanned
• Color scanners and cameras use color-filter arrays or mosaics to capture red, green, and blue values for each pixel
• The resolution of cameras and scanners is determined by the fixed number of pixels in the array and is usually quoted using the total count of pixels
• Vector images are often used for text, diagrams, mechanical drawings, and applications where crispness and precision are important