PPT: Scaling Bitmaps and Movies for Slide Shows

ID: q111822

The information in this article applies to:

Microsoft PowerPoint for Windows 95, version 7.0
Microsoft PowerPoint for Windows, versions 3.0, 4.0, 4.0a, 4.0c
Microsoft PowerPoint for the Macintosh, versions 3.0, 3.0b, 4.0

SYMPTOMS

If you run a PowerPoint slide show that contains imported bitmaps or video clips, the bitmaps may appear distorted and/or the movies may play irregularly. In both cases, they look and show as expected when you edit the slide in 100-percent view.

When running an on-screen slide show in PowerPoint, the slides and their contents are scaled proportionally to use as much of the screen as possible. Because bitmaps do not scale well, it is important to pre-scale bitmaps (including QuickTime and AVI movies) so that they are rescaled to their original imported proportions during the slide show. Improper scaling can result in choppy/jerky playback of movies or distorted bitmaps during a slide show.

RESOLUTION

To avoid distortion of bitmapped graphics, follow these steps:

1. Select the imported graphic, and then click Scale on the Draw menu.

2. In the Scale dialog box, click "Best Scale for Slide Show" and select

   the resolution of the video driver on the computer system that will
   display the slide show.

3. Click OK.

MORE INFORMATION

You can use the following procedure to help you choose the appropriate pre-scaling factor:

1. Determine the width/height ratio of the target display and the

   slide using the following table. (The dimensions for display drivers
   are listed in pixels.)

      Display/Driver    Width   Height   Ratio
      ----------------  -----   ------   -------
      Standard VGA      640     480      1.33333
      Macintosh Plus    512     384      1.33333
      Macintosh E-Mac   832     624      1.33333
      Macintosh PBook   640     400      1.6
      PP3 Letter Paper  10.5    7.5      1.33333
      PP3 On-Screen     10.5    7.5      1.33333
      PP3 35 mm         11.25   7.5      1.5

   If you do not know the width/height ratio of your target display, you
   can do the following:

      Windows:   Use the Windows Paintbrush utility to examine the
                 default Image Attributes on the target machine. Consult
                 your "Microsoft Windows User's Guide" or the Help
                 utility in Paintbrush for additional information.

      Macintosh: Consult the display hardware documentation or the
                 manufacturer of your display card, or use a
                 third-party utility, such as TattleTale, to get this
                 information.

2. Determine the pixel resolution (pixels per display inch) of the

   display.

   NOTE: For the following calculations, the horizontal pixel
   resolution and vertical pixel resolution are assumed to be
   identical (square pixels). Standard values are:

      Windows:   Pixel resolution = 96 dpi
      Macintosh: Pixel resolution = 72 dpi

3. Determine the scaling factor by comparing the width/height ratios

   for the target display and slide size (you can find the slide size
   by clicking Slide Setup on the File menu) and using one of the
   following formulas.

   If target display ratio is greater than or equal to the slide
   ratio, use the following formula:

                                        Pixel resolution(pixels/inch)
   Scale % = 100 * Slide Height(inch) * -----------------------------
                                            Display Height(pixels)

   Example for VGA: 150% = 100 * 7.5 * (96 / 480)

   If the target display ratio is less than or equal to the slide
   ratio, use the following formula:

                                       Pixel Resolution(pixels/inch)
   Scale % = 100 * Slide Width(inch) * -----------------------------
                                           Display Width(pixels)

   Example for Mac Plus: 197% = 100 * 10.5 * (72 / 384)

4. Make sure that the object to be scaled is at its original

   proportions by doing the following:

   Windows:   Hold down SHIFT and double-click one of the object's
              resize handles.

   Macintosh: Hold down SHIFT+OPTION and double-click one of the
              object's resize handles.

5. Use the Scale command to prescale the object using the scaling

   percentage calculated in Step 3.

NOTE: You can use these instructions to create a presentation on one platform intended for display on another platform as long as you know the display size and resolution of the target display.

Additional query words: 3.00 3.00b 4.00 4.00a 4.00c 7.00 power point powerpt scale movie bitmap macppt ppt95 winppt powerpt

Keywords          : kbgraphic
Version           : windows:3.0,4.0,4.0a,4.0c,7.0,97; macintosh:3.0,4.0,98
Platform          : MACINTOSH WINDOWS
Hardware          : MAC x86
Issue type        : kbhowto

Last Reviewed: August 3, 1998