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信息处理技术

信息处理技术. Chapter 4: File Management, Virus Protection, and Backup. Chapter 1: Computer, Internet, Web, and E-Mail Basics. 1. 1. 1. 1. Chapter 7 Preview. After this chapter, you should be able to:

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信息处理技术

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  1. 信息处理技术

  2. Chapter 7: Digital Media Chapter 4: File Management, Virus Protection, and Backup Chapter 1: Computer, Internet, Web, and E-Mail Basics 1 1 1 1

  3. Chapter 7 Preview After this chapter, you should be able to: • Describe the advantages, disadvantages, and uses for digital media, such as bitmap graphics, vector graphics, 3-D graphics, 3-D animations, desktop video, waveform audio, MIDI music, speech synthesis, and speech recognition • List the equipment and software that can be used to work with various types of digital media • Identify digital media files by their file extensions • Understand the advantages and disadvantages of using each type of digital media on the Web Chapter 7: Digital Media

  4. Chapter 7 Preview • Explain how resolution, image size, color depth, and color palettes can be manipulated to adjust the file size of a bitmap graphic • Describe procedures required to convert bitmap graphics into vectors and vector graphics into bitmaps • Explain how wireframes, rendering, and ray tracing apply to 3-D graphics • Define the differences between digital video and 3-D animation Chapter 7: Digital Media

  5. Chapter 7 Preview • Describe how to shoot, capture, edit, and process digital video • Explain how window size, frame rate, and compression affect file size for a desktop video • Describe the formats used for digital music • Explain how to download music files and transfer them to portable audio players Chapter 7: Digital Media

  6. Chapter 7 Outline • Section A • Bitmap Graphics 位图 • Section B • Vector and 3-D Graphics矢量及三维图 • Section C • Digital Video 数字视频 • Section D • Digital Sound 数字音频 Chapter 7: Digital Media

  7. Chapter 7Digital Media数字媒体 Section A: Bitmap Graphics 位图 Computer Concepts 8th Edition

  8. Bitmap Basics: What is a bitmap graphic? • Bitmap graphic – “raster graphic”, consists of a grid of dots • The color of each dot is stored as a binary number • Example Page 344 Chapter 7: Digital Media

  9. How do I create bitmap images? • Paint software – graphics software for creating bitmap graphics • Adobe Photoshop • Jasc Paint Shop Pro • Microsoft Paint • Bit-by-bit editing Page 344 Chapter 7: Digital Media

  10. How do I convert a printed image into a bitmap? Page 345 Chapter 7: Digital Media

  11. When should I use a digital camera rather than a scanner? • Digital camera – digitizes real objects • Takes photo in digital format, which you can then transfer directly to your computer Page 345 Chapter 7: Digital Media

  12. How does a digital camera store images? • Some digital cameras store images on floppy disks, CDs, mini-CDs, or miniature hard disk drives • Solid state storage – popular technology for digital camera memory modules • Holds data without consuming power • Memory card Page 346 Chapter 7: Digital Media

  13. How can I get the images out of the camera? • Media transfer, e.g disk • Direct cable transfer • Infrared port • Card readers • Floppy disk adapters • E-mail Page 346 Chapter 7: Digital Media

  14. Modifying Bitmap Graphics: What characteristics of a bitmap can I modify? • You can use graphics software to modify or edit bitmap graphics by changing any individual pixels • Retouch • Repair • Remove red eye or erase “rabbit ears” • Bitmap graphics can require large amounts of storage, and take a long time to load Page 347 Chapter 7: Digital Media

  15. Image Resolution: How does resolution pertain to bitmap graphics? • Resolution – dimensions of the grid that forms a bitmap graphic • Number of horizontal and vertical pixels that it contains • 150 x 100 – 150 pixels across and 100 pixels high, 1600 x 1200 • 1.9 Megapixels (1600x1200) • 3.5 Megapixels (2160x1440) Page 347 Chapter 7: Digital Media

  16. Size of Graphics & Image • Each pixel is 1 or more bits • Enlarging an image pixelates it Chapter 7: Digital Media

  17. How do I specify the size of a printed image? • Most graphics software lets you specify the size at which an image is printed without changing the resolution of the bitmap graphic • Get better printout if an image meets or exceeds the printers dpi (dots per inch) Page 348 Chapter 7: Digital Media

  18. How does a bitmap’s resolution relate to what I see on the screen? • Typically, one pixel on the graphic corresponds to one pixel on the screen • If image is larger than screen, you will have to scroll Page 348 Chapter 7: Digital Media

  19. Can I change a graphic’s file size? • Cropping – process of selecting part of an image • Resolution dependent – quality of the image depends on its resolution • Can reduce image quality • Pixel interpolation – creates new pixels by averaging the colors of nearby pixels • Pixelated – undesirable jagged appearance Page 349 Chapter 7: Digital Media

  20. Can I change a graphic’s file size? Page 349 Chapter 7: Digital Media

  21. Color Depth and Palettes: What is color depth? • The number of colors that are available for use in an image • Larger number, better quality and larger file size. Why? • 8-bit • 24-bit or True Color Page 350 Chapter 7: Digital Media

  22. How does a color palette work? 8-bits each Page 351 Chapter 7: Digital Media

  23. How do I select a color palette? • Use color palette or color picker tool • Grayscale palette – displays an image using shades of gray (usually 256 shades of gray) • System palette – selection of colors used by the operating system • Windows has 20 permanent colors and 236 that can be changed • Web palette – standard set of colors used by the Internet Web browsers Page 352 Chapter 7: Digital Media

  24. What if a palette doesn’t contain the colors needed for an image? • Dithering – uses patterns composed of two or more colors to produce the illusion of additional colors and shading, relying on the human eye to blend colors and shapes Page 352-353 Chapter 7: Digital Media

  25. Bitmap Graphics Formats: Are there different kinds of bitmap graphics? • BMP – native bitmap graphic file format of Microsoft Windows OS • PCX – one of original personal computer bitmap graphics file formats (8-bit – 256 color) • TIFF (Tag Image File Format) – highly flexible and platform-independent graphics file format • Supports True Color • Used by scanners and digital cameras Page 353 Chapter 7: Digital Media

  26. Are there different kinds of bitmap graphics? • JPEG – graphics format with built-in compression • You control level of compression • Uses True Color • GIF – limited to 256 colors • PNG – 48-bit True Color, compresses without losing data • Public domain format Page 353 Chapter 7: Digital Media

  27. How do I know which graphics format to use? • BMP – Buttons and other controls • PCX – Not used with much frequency • TIFF – High-resolution images and photos • JPEG – Photographic or scanned images • GIF – Popular for Web graphics • PNG – Alternative to GIF Page 354 Chapter 7: Digital Media

  28. Chapter 7Digital Media Section B: Vector and 3-D Graphics 矢量及三维图 Computer Concepts 8th Edition

  29. Vector Graphics Basics: What is a vector graphic? • Consists of set of instructions for re-creating a picture • Contains the instructions that the computer needs to create the shape, size, position, and color for each object in an image Page 356 Chapter 7: Digital Media

  30. What is a vector graphic? Page 356 Chapter 7: Digital Media

  31. How do vector graphics compare with bitmap graphics? • Vectors resize better than bitmaps • Vector images usually require less storage space than bitmaps • It is easier to edit an object in a vector graphic than an object in bitmap graphic • Vector graphics are not usually as realistic as bitmap images, simpler and more like a cartoon or linedrawing Page 357 Chapter 7: Digital Media

  32. What tools do I need to create vector graphics? • Digitizing tablet – device that provides a flat surface for a paper-based drawing • AutoCAD for architects Page 358 Chapter 7: Digital Media

  33. What tools do I need to create vector graphics? Page 359 Chapter 7: Digital Media

  34. Vector-to-Bitmap Conversion: Is it possible to convert a vector graphic into a bitmap? • Rasterization works by superimposing a grid over a vector image, and determining the color for each pixel • Once converted, the resulting graphic no longer has the qualities of a vector graphic • Metafiles - bitmaps & vectors Page 360 Chapter 7: Digital Media

  35. How about converting a bitmap graphic into a vector graphic? • This process is more difficult • Tracing software locates the edges of objects in a bitmap image and converts the resulting shapes into vector graphics objects Page 360 Chapter 7: Digital Media

  36. Vector Graphics on the Web: Do vector graphics work on the Web? • Browsers support a limited number of graphics formats – GIF and JPEG • Support for vector graphics has been slow, but plug-ins and players are currently available Page 361 Chapter 7: Digital Media

  37. Which vector graphics formats can be used on the Web? • SVG (Scalable Vector Graphics) – designed for the Web • Automatically resized when displayed on different screens • Uses <EMBED> tag • Flash graphics – can be static or animated and require less space than SVG graphics, but require a browser plug-in to be viewed • Animated GIFs much larger Page 361 Chapter 7: Digital Media

  38. Advantages of Using Vector Graphics on the Web • Consistent Quality • Looks the same on all screens • Resizes • Searchable • Text in vector, e.g. labels • Smaller than bitmaps Chapter 7: Digital Media

  39. 3-D Graphics: How do vector graphics relate to 3-D graphics? • 3-D graphics – stored as a set of instructions • Wireframe – framework for a 3-D graphic • Rendering – process of covering a wireframe with surface color and texture • Ray tracing – technique for adding light and shadows to a 3-D image Page 362 Chapter 7: Digital Media

  40. How do vector graphics relate to 3-D graphics? Page 362 Chapter 7: Digital Media

  41. How do vector graphics relate to 3-D graphics? • Rotating the graphic Page 362 Chapter 7: Digital Media

  42. What do I need to create 3-D graphics? Page 363 Chapter 7: Digital Media

  43. Is it possible to animate 3-D graphics? • 3-D graphics can be animated • Pixar Animation Studios • DreamWorks • Toy Story, LOR, etc. • Special effects can be created and incorporated into final footage • 3-D computer game animation happens in “real-time,” rendered as you play • Graphics cards Page 363 Chapter 7: Digital Media

  44. VRML • Virtual Reality Markup Language • Similar to vector graphics • Interpreted by plug-ins • Allows you to “move thru” graphics • http://prt.fernuni-hagen.de/lehre/KURSE/PRT001/course_main/node19.html Chapter 7: Digital Media

  45. Chapter 7Digital Media Section C: Digital Video 数字视频 Computer Concepts 8th Edition

  46. Desktop Video Basics: What is digital video? • Uses bits to store color and brightness data for each video frame • Stored on hard disks, CDs, DVDs, videotapes, memory cards, or the Web • Footage can be supplied by: • Video camera • Videotape • Television • DVD • Digital recording device Page 365 Chapter 7: Digital Media

  47. What is digital video? • Video is composed of a series of frames • Each frame is essentially a still picture (can be stored as bitmap graphic) • Frame rate – number of frames per second Page 365 Chapter 7: Digital Media

  48. Are there different kinds of digital videos? • Desktop video • Web-based video • DVD video • PDA video Page 365 Chapter 7: Digital Media

  49. How do I create digital video? Page 366 Chapter 7: Digital Media

  50. Is it necessary to use a digital video camera for filming digital video? • You can use analog or digital video camera to shoot footage • Digital video camera – stores footage as a series of bits • Analog video camera –stores as continuous track of magnetic patterns • Must be digitized • Videoconferencing cameras – attach directly to a computer Page 366 Chapter 7: Digital Media

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