Knowledge Base

PPT98: How to Scale Bitmaps and Movies for Better Slide Shows

Article ID: 188946

Article Last Modified on 10/3/2002

APPLIES TO

Microsoft PowerPoint 98 for Macintosh

This article was previously published under Q188946

For a Microsoft PowerPoint 2001 for Mac version of this article, see 279026.
For a Microsoft PowerPoint 2000 version of this article, see 251202.
For a Microsoft PowerPoint 97 version of this article, see 189971.
For a Microsoft PowerPoint 7.0 and earlier version of this article, see 111822.

SYMPTOMS

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

CAUSE

Microsoft PowerPoint 98 Macintosh Edition and Microsoft PowerPoint 98 Viewer do not display slides at full screen resolution. The display resolution is 16 pixels shorter vertically and 20 pixels narrower horizontally than full screen resolution.

Because of this, when you run a slide show, PowerPoint then scales the slides and their contents proportionally to use as much of the smaller screen size as possible. Because bitmaps do not scale well, it is important to pre-scale bitmaps (including QuickTime and Audio-Video Interleaved [AVI] movies) so that they are rescaled to their original imported proportions during the slide show. Improper scaling can result in choppy or jerky playback of movies, or distorted bitmaps during a slide show.

WORKAROUND

Determine the width/height ratio of the target display and the slide by using the following table. Standard slides have a width/height ratio of 1.33333:1. (The dimensions for display drivers are listed in pixels.)

NOTE: This table is not comprehensive; it only contains a sampling of display resolutions as a reference.

Display/Driver	Width	Height	Ratio
Standard VGA	640	480	1.33333 : 1
Macintosh Studio Display (Min)	640	480	1.33333 : 1
Macintosh Studio Display (Max)	1,600	1,200	1.33333 : 1
Macintosh Cinema Display (Min)	800	500	1.6 : 1
Macintosh Cinema Display (Max)	1,600	1,024	1.5625 : 1
Letter Paper	10"	7.5"	1.33333 : 1
On-Screen	10"	7.5"	1.33333 : 1
35mm Slides	11.25"	7.5"	1.5 : 1

If you do not know the width/height ratio of your target display, use the appropriate method for your operating system to determine the width/height ratio.

Microsoft Windows

Click Start, point to Settings, and then click Control Panel.
Double-click the Display icon.
Click the Settings tab and note the screen resolution setting under Desktop area or Screen area.
To calculate the width-to-height ratio for the display screen, divide the first number by the second number.

For example, if the resolution listed is 1,280 by 1,024 pixels, the width/height ratio is 1,280 divided by 1,024, which equals 1.25. The width of the screen is 25 percent wider than it is tall.

Macintosh

On the Apple menu, point to Control Panels, and then click Monitors or Monitors and Sound.
Click Monitor.
Note the screen resolution that is selected under Resolution.
To calculate the width-to-height ratio for the display screen, divide the first number by the second number.

For example, if the resolution listed is 1,280 by 1,024 pixels, the width/height ratio is 1,280 divided by 1,024, which equals 1.25. The width of the screen is 25 percent wider than it is tall.

After you have determined the width/height ratio of the target display, compare it to the width/height ratio of the presentation. If the two are not equal, you must change the slide's height as necessary.
1. On the File menu, click Page Setup.
2. Calulate the new Slide Height as follows:
  
  Slide Height = Slide Width / (Width/Height Ratio)
  
  For example, on a Macintosh Cinema Display with a screen resolution of 800 x 500, a width/height ratio of 1.6:1, and a default height of 10 inches, use a slide height of 6.25 inches:
  
  Slide Height = 10" / 1.6 = 6.25"
3. In the Height box, type the slide height that you calculated in the previous step, and then click OK.
  
  NOTE: If you change the slide height of an existing presentation, PowerPoint resizes all shapes to match the new slide size, which distorts images on all slides. Microsoft recommends that you change the slide height first, before you add any images or movies to your presentation.
In Slide view, click the video or bitmap that you want to resize.
On the Format menu, click Picture, and then click the Size tab.
Click Reset, and then click OK.
On the Format menu, click Picture, and then click the Size tab.
Click to select the Lock aspect ratio check box.
Click to select the Best scale for slide show check box.
In the Resolution list, click the resolution that most closely matches the resolution of the display on which the presentation will be shown.
Click to clear the Best scale for slide show check box.
Use the following formula to calculate the actual percentage to scale the image:

Actual Percentage = ((Width in Pixels - 20)/Width in Pixels) * Current Percentage

For example, if the current percentage for a Best scale for slide show of 800 by 600 is 120 percent, the actual percentage is 117 percent:

((800 - 20)/800) * 120% = Actual Percentage

(780/800) * 120% = Actual Percentage

0.975 * 120% = Actual Percentage

117% = Actual Percentage
In the Width text box, type the actual percentage that you calculated in the previous step, and then click OK. Because you selected the Lock aspect ratio setting earlier, PowerPoint scales the image height proportionately.

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

Additional query words: power point powerpt scale movie bitmap macppt fuzzy jaggy blurry sleepy dopey doc sneezy grumpy happy bashful

Keywords: kbprb kbgraphic kbusage KB188946

Microsoft KB Archive/188946

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