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Graphic File Formats

Graphic File Formats. Objectives. Understand the difference between two major categories of computer graphic images Investigate the differences between various file formats Generalize formats to the type of software that creates them

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Graphic File Formats

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  1. Graphic File Formats

  2. Objectives • Understand the difference between two major categories of computer graphic images • Investigate the differences between various file formats • Generalize formats to the type of software that creates them • Establish a philosophy of use for various graphic file formats

  3. Native File Format

  4. Two Categories of Formats Bitmapped Vector

  5. Bitmapped Formats • Images are created by individual pixels displayed in various colors.

  6. Bitmapped Formats • Remember, each pixel can hold up to 24 bits (3 bytes) of color information

  7. Bitmapped Formats • Bitmapped formats have a fixed resolution • Can NOT be resized without some effects on the clarity of the image

  8. Bitmapped Formats • Bitmapped formats are best suited for “photographic” quality images

  9. Bitmapped Formats • Scanners and digital cameras acquire images in bitmapped formats

  10. TIF JPG BMP PIC GIF PNG PSD PCX Common Bitmapped File Formats

  11. TIF Format • Tagged Image File format. • Standard between MAC and PC bitmap graphics. • Handles multiple channel files. • i.e. RGB • i.e. Alpha Channels

  12. TIF Format • Writes a "header" that tells software what information is contained. • Header may increase file size. • Not really a problem with modern hardware

  13. TIF Format • Uses a LZW compression scheme. • No data lost, just compressed.

  14. JPG (Jpeg) Format • Joint Photographic Experts Group • A file format and compression scheme. • Emerging as a standard format for photos. • Internet use.

  15. JPG (Jpeg) Format • “Lossy” compression- • Reduces data during save. • Data loss can be controlled. • Can reduce file size in a ratio between 10:1 and 20:1.

  16. BMP Format • Microsoft native file format • PC system compatible • DOS • Windows • OS/2 • No MAC compatibility.

  17. BMP Format • Photoshop encodes to 1, 4, 8, 24 bit color but .bmp can not support channels. • No file space savings for photos with .bmp. • - Try a JPG!

  18. PIC (Pict) Format • A MAC native file format. • Not PC operating system compatible. • Can do 24 bit color plus an extra 8 bits. • Any MAC monitor can display 32 bit PICT files

  19. PICT Format • MAC system format used to exchange data via clipboard.

  20. GIF Format • Graphics Interchange Format. • Created by Compuserve to speed downloading of graphics. • Limited to 256 colors. • Compression format

  21. GIF Format • Can be both interlaced and non-interlaced • Common Internet file format • 87 • 89a (interlaced, with one transparent color)

  22. PNG Format • Portable Network Graphics • New format targeted for Internet use • Can support up to 48 bit color • Big compression factor • Can support multiple transparent colors

  23. PSD Format • Photoshop native file format. • Supports all image types from line art to photos. • Increasing compatibility with other software.

  24. PSD Format • PSD can hold an infinite amount of channels! • Each layer can hold 24 channels. • Infinite amount of layers are possible. • Subject to available RAM!!!!

  25. Multi-Channel to .GIF

  26. PCX Format • From ZSoft Corp. • Many versions exist. • Great for indexed, grayscale and line art. • Supports only one channel.

  27. PCX Format • Photoshop only supports PCX version 5! • Convert .pcx to RGB to use most Photoshop tools. • PC Paintbrush format.

  28. Kodak Photo CD - PCD • Kodak format for images stored on Kodak Photo CD. • Uses YCC color model. • Limited to five image sizes.

  29. Kodak Photo CD - PCD • Photoshop opens as a LAB color model. • Photoshop can not save as a PhotoCD format.

  30. Bitmapped FormatsAnd Pixels

  31. Vector Formats • Images are a series of pixels that are "turned on" based on a mathematical formula.

  32. Vector Formats • Vector Formats are basically defined by shapes and lines • No more than 256 colors • Clip Art

  33. Vector Formats • Not resolution dependent • Infinitely scalable • Not appropriate for photo realistic • images

  34. WMF AI Post Script CGM Fonts DRW CIL Common Vector File Formats

  35. WMF Format • Windows Metafile Format. • Designed for easy exchange between Windows programs via clipboard. • Common clipart format.

  36. PostScript Format • Developed by Adobe Systems for typefaces. • Expanded for many graphic elements. • Encapsulated Post Script (.eps) is of this format.

  37. PDF Format • Adobe Acrobat file format. • Portable Document Format

  38. PDF Format • Integrates color, graphics and text • Searchable format

  39. CGM Format • Computer Graphics Metafile • Most common DOS-based format • Used by - • Harvard Graphics • Freelance Graphics • Others

  40. CGM Format • Older versions of format may not load cleanly into modern versions of software • Can support very elaborate graphics • A "schizophrenic" file format!

  41. Vector FormatsAnd Shapes

  42. Software Choices • Traditionally, different software creates either bitmapped or vector art • This is changing!

  43. For bitmapped, names that include the words “Paint” or “Photo” indicates that the primary function of the software is to create and manipulate bitmapped formats Software Choices

  44. For bitmapped, names that include the words “Paint” or “Photo” indicates that the primary function of the software is to create and manipulate bitmapped formats Examples – Adobe Photoshop Deluxe Paint Photoshop Elements Macromedia Fireworks Corel Photo-Paint Paint Shop Pro Software Choices

  45. For vector art, names that include the words “Draw” or “Illustrator” indicates that the primary function of the software is to create and manipulate bitmapped formats Software Choices

  46. For vector art, names that include the words “Draw” or “Illustrator” indicates that the primary function of the software is to create and manipulate bitmapped formats Examples – Adobe Illustrator Corel DRAW Microsoft Draw Macromedia Freehand Serif DrawPlus Macromedia Flash Software Choices

  47. Software Choices • Most modern versions of bitmapped software also include draw tools • Photoshop 6.0 now can create vector art.

  48. Software Choices • Adobe Acrobat, desktop publishing, etc. software is friendly to both categories of graphic types

  49. When to Use What and When!?!? What are the requirements of your output device?

  50. When to Use What and When!?!? Image Quality File Size

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