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Graphics: Part 2 of 3

Bitmap Graphics
Object-oriented graphic vs. bitmap graphic

Bitmap graphics are commonly created by basic painting packages, such as Microsoft Paint. Most scanning packages also utilize bitmap formats. Bitmaps are comprised from a series of small square dots (pixels). Depending on the format of the particular bitmap, each of these dots can be black, white, some particular color, or a shade of gray.

Limitations of bitmap graphics:

  • Because bitmaps are made up of dots, sizing the graphic may distort it. Sizing the graphic proportionally minimizes the distortion.
  • Bitmap graphics can be very large. Scanned bitmaps at 300 dpi (dots per inch) can easily exceed 1 megabyte (MB). This causes slow screen redraws and creates larger Publisher files. Printing problems may also occur with large images.
  • Bitmaps do not typically output at as high a resolution as an equivalent object-oriented graphic format.
Object-Oriented Graphics

Object-oriented graphics, on the other hand, are not comprised of a series of dots. They are a set of instructions that tell the computer to draw lines, boxes, polygons, and so on. Such a file is basically an equation for generating the image, rather than the actual pixel by pixel representation.

Object-oriented graphics have several advantages over bitmaps.

  • A graphic can usually be resized without distorting the image. Object-oriented graphics are generated by a formula; therefore, if you resize the image, the application recalculates the formula to compensate for the change in size.
  • Object-oriented graphic files are much smaller in size.
  • They output at the highest resolution supported by the output device. In other words, if you send an object-oriented graphic to a 1024 x 1024 resolution printer, the graphic would recalculate and output at that resolution. A bitmap, on the other hand, is always limited by the initial resolution at which it was created. In most cases, this is no better than the screen resolution, 75 DPI for VGA, unless the image was scanned.

Typical programs using object-oriented graphics are CorelDRAW!, Micrografx Designer, Microsoft PowerPoint, Microsoft Excel, Adobe Illustrator and many others.

Information courtesy of Microsoft.com
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