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  1. Section A Bitmap Graphics CHAPTER 7 Digital Media PARSONS/OJA Page 330

  2. Section A Chapter 7 Digital Media The Big Picture… • Bitmap graphics • Converts image to “off and on” • Pixels • Number • Edit • Changing size of image. Become pixelated. • Large files • Compressing bitmap files • JPEG, GIF, PNG • Images can be viewed by web browser Page 332

  3. Section A Chapter 7 Digital Media The Big Picture… • Vector graphic – consists of set of instructions for re-creating a picture • Resize better • Less storage space • Easier to edit • Not as realistic • 3-D Graphic • Design, cartoon • Requires computing power Page 332

  4. Section A Chapter 7 Digital Media The Big Picture… • Digital camera • Number of pixels • Type of storage • Method of transferring images to computer Page 332

  5. Section A Chapter 7 Digital Media The Big Picture… • Desktop video • Series of images • Compression • Transfer to computer • Editing • Decent computing capabilities • Conversion from analog Page 332

  6. Section A Chapter 7 Digital Media The Big Picture… • Digital sound • MP3: method of compression • MIDI: used to store music data • Speech synthesis: used to produce “spoken words” • Voice recognition software: problems Page 332

  7. Section A Chapter 7 Bitmap Graphics Bitmap Basics: What is a bitmap graphic? • Bitmap graphic – “raster graphic”, consists of a grid of dots, and the color of each dot is stored as a binary number Page 332

  8. Section A Chapter 7 Bitmap Graphics Where can I find bitmap graphics? • Often used to create realistic images • Cartoons in video games • 3-D graphics software • Digital cameras • E-mail photos Page 332

  9. Section A Chapter 7 Bitmap Graphics How do I create bitmap images? • Paint software – graphics software for creating bitmap graphics • Adobe Photoshop • Jasc Paint Shop Pro • Microsoft Paint Page 332

  10. Section A Chapter 7 Bitmap Graphics Scanners and Cameras: How do I convert a printed image into a bitmap? • Scanner – converts printed pages and images into a bitmap graphic • Divides image into fine grid of cells, and assigns a digital value for the color of each cell • Values are transferred to your computer’s disk and stored as a bitmap Page 333

  11. Section A Chapter 7 Bitmap Graphics 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 333

  12. Section A Chapter 7 Bitmap Graphics How does a digital camera store images? • The type of memory module used by a digital camera depends on the brand and model • Flash memory – popular technology for digital camera memory modules • Holds data without consuming power Page 334

  13. Section A Chapter 7 Bitmap Graphics How does a digital camera store images? Page 334

  14. Section A Chapter 7 Bitmap Graphics How do I get the images out of the camera? • Direct cable transfer – Fire Wire ports are used to transfer data • Infrared port – cameras “beam” the data to computer’s infrared port • Memory card readers – small device connected to computer and designed to read flash cards • Floppy disk adapters – adapter shaped like a floppy with slot for a flash memory module Page 334-335

  15. Section A Chapter 7 Bitmap Graphics How do I get the images out of the camera? Page 334-335

  16. Section A Chapter 7 Bitmap Graphics Modifying Bitmap Graphics: What characteristics of a bitmap can I modify? • You can use graphics software to modify or edit bitmap graphics by changing individual pixels • Retouch • Repair • Remove red eye or erase “rabbit ears” • Bitmap graphics require large amounts of storage, and take long time to load • May not fit on a floppy disk Page 335

  17. Section A Chapter 7 Bitmap Graphics 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 Page 335

  18. Section A Chapter 7 Bitmap Graphics How does resolution relate to image quality? • High-resolution graphics contain more data than low-resolution • Better printouts • Megapixels – total number of pixels in a graphic Page 335

  19. Section A Chapter 7 Bitmap Graphics How does resolution relate to the file size of a graphic? • Each pixel is stored as one or more bits • More pixels means larger file size Page 336

  20. Section A Chapter 7 Bitmap Graphics How does resolution relate to the physical size of an image? • Bitmap has no fixed physical size • Size depends on density • Graphic retains same resolution no matter how much you stretch or shrink the graphics physical size Page 336

  21. Section A Chapter 7 Bitmap Graphics How does resolution relate to the physical size of an image? Page 336

  22. Section A Chapter 7 Bitmap Graphics How do I specify the size of a printed image? • Most graphics software lets you specify the size at which 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 336

  23. Section A Chapter 7 Bitmap Graphics How does a bitmap’s resolution relate to what I see on the screen? • Typically, one pixel corresponds to one pixel on the screen • If image is larger than screen, you will have to scroll Page 336

  24. Section A Chapter 7 Bitmap Graphics 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 • If you attempt to enlarge a bitmap, computer must add pixels • Pixel interpolation – creates new pixels by averages the colors of nearby pixels • Pixelated – undesirable bitmappy appearance Page 337

  25. Section A Chapter 7 Bitmap Graphics Can I change a graphic’s file size? Page 337

  26. Section A Chapter 7 Bitmap Graphics Color Depth and Palettes: What is color depth? • Color depth – is the number of colors that are available for use in an image • Larger number, better quality and larger file size Page 338

  27. Section A Chapter 7 Bitmap Graphics How does color depth relate to file size? • True color bitmap (24-bit bitmap) – 16.7 million colors • Each pixel requires 3 bytes of storage • Color based on intensity levels or red, green, blue • 8-bits red, 8-bits green, 8-bits blue (24-bits) • 32-bit bitmap – 16.7 million colors plus special effects Page 339

  28. Section A Chapter 7 Bitmap Graphics How can I reduce color depth? • Reducing color depth can reduce size of file • To reduce color depth, manipulate color palette • Color palette – digital version of artist’s palette that holds the selection of colors for use • 256 colors – eight bits per pixel (1/3 size required for true color bitmap) Page 339

  29. Section A Chapter 7 Bitmap Graphics How does a color palette work? Page 339

  30. Section A Chapter 7 Bitmap Graphics 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 340

  31. Section A Chapter 7 Bitmap Graphics So what should I do about color depth? • Bitmap graphics that you wish to print should remain in True Color format • Those sent in e-mail or posted on Web site should be reduced to 256-color palette Page 341

  32. Section A Chapter 7 Bitmap Graphics 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 341

  33. Section A Chapter 7 Bitmap Graphics 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 342

  34. Section A Chapter 7 Bitmap Graphics How do I know which graphics format to use? • Selecting the best graphics file format to use depends on what you intend to do with the image • Scanned and digital images – could be stored as JPEG or TIFF format • Images for web pages – GIF or JPEG format • Designing Windows controls – BMP format Page 342

  35. Section B Chapter 7 Vector and 3-D Graphics Vector Graphics Basics: What is a vector graphic? • Vector graphic – consists of set of instructions for re-creating a picture • Instead of storing the color value for each pixel, a vector graphic file contains the instructions that the computer needs to create the shape, size, position, and color for each object in an image Page 344

  36. Section B Chapter 7 Vector and 3-D Graphics What is a vector graphic? Page 344

  37. Section B Chapter 7 Vector and 3-D Graphics How can I identify vector graphics? • Flat, cartoon-like quality • Filename extension • .wmf • .dxt • .mgx • .eps • .pict • .cgm Page 345

  38. Section B Chapter 7 Vector and 3-D Graphics What are the advantages and disadvantages of vector graphics? Page 345

  39. Section B Chapter 7 Vector and 3-D Graphics What are the advantages and disadvantages of vector 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 tend not to produce images that are as realistic as bitmap images Page 345-346

  40. Section B Chapter 7 Vector and 3-D Graphics What are the advantages and disadvantages of vector graphics? Page 346

  41. Section B Chapter 7 Vector and 3-D Graphics What tools do I need to create vector graphics? • Drawing software – vector graphics software • Helps you easily edit individual objects by changing their sizes, shapes, positions or colors Page 346-347

  42. Section B Chapter 7 Vector and 3-D Graphics What tools do I need to create vector graphics? • Gradient – smooth blending of shades from one color to another, or from light to dark • Metafiles – graphics that contain both bitmap and vector data • Apply bitmap texture to vector graphic Page 348

  43. Section B Chapter 7 Vector and 3-D Graphics What tools do I need to create vector graphics? Page 348

  44. Section B Chapter 7 Vector and 3-D Graphics 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 Page 348

  45. Section B Chapter 7 Vector and 3-D Graphics How about converting a bitmap graphic into a vector? • Tracing software – locates the edges of objects in a bitmap image and converts the resulting shapes into vector graphics objects Page 348

  46. Section B Chapter 7 Vector and 3-D Graphics 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 349

  47. Section B Chapter 7 Vector and 3-D Graphics 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 Page 349

  48. Section B Chapter 7 Vector and 3-D Graphics What are the advantages of using vector graphics on the Web? • Vector graphics appear with same consistent quality on all computer screens • Any text contained in a vector image is stored as actual text, not just a series of colored dots • Vector graphics on the Web have compact file sizes Page 349

  49. Section B Chapter 7 Vector and 3-D Graphics How do vector graphics relate to 3-D graphics? Page 350

  50. Section B Chapter 7 Vector and 3-D Graphics How do vector graphics relate to 3-D graphics? Page 350