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Digital Media

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

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Digital Media

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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

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