There’s no native feature in PowerPoint that lets you run your slides in a random order. But, where there's a will, there's a way! And with a touch of VBA, we've got a way.
Have you ever noticed the PowerPoint icons that show up on your desktop or inside Windows File Explorer? Sometimes the default application icon is shown and sometimes you see a PowerPoint preview thumbnail of a slide from your presentation. You’re about to learn everything you ever needed to know about how these work, how to generate them, and how to get rid of them.
Default PowerPoint application icons
You may or may not know that when you save a presentation it’s saved as a pptx file. When you create a template the extension used is potx. And if you save your presentation as a self-starting slide show then ppsx is used. When you view these three formats in Windows File Explorer, the icon you see reflects that format or file extension:
These icons correspond to the three ‘standard’ formats: presentation, template and slide show. If you add macros to any of these files the formats change to ones ending in ‘m’ and the icons change, illustrating the presence of macros with an exclamation mark (Office 365 / PowerPoint 2016 and 2019):
How to create custom PowerPoint preview thumbnail icons
You might be happy to create and distribute your beloved PowerPoint content using these default icons but when you have a lot of them all in the same place, it’s nice to see a preview of what’s inside the separate files. Providing a visual cue of the file’s content can also help improve accessibility for your users.
Here’s an example of three presentations with the preview thumbnail set in each PowerPoint file:
This makes it easy to see what each file contains! So how do you activate these thumbnails?
Preview thumbnails are created by PowerPoint taking a static capture of your first non-hidden slide. If that slide contains animations, you’ll need to take this into account because the thumbnail will be generated from what you see in the normal view, not the slide show view.
Here’s how you create a thumbnail preview image for your PowerPoint file:
1. Open your presentation in PowerPoint
2. Click File followed by Info to open what Microsoft call the backstage
3. Over on the right-hand side, click the Properties heading then click Advanced Properties in the drop-down menu
4. Click the Summary tab in the window that opens
5. At the bottom of the window, tick the Save preview picture check box:
6. Click OK and save your presentation.
Back in Windows File Explorer, or your desktop if that’s where your presentation is, press F5 to refresh the view and your preview thumbnail will magically appear. If you don’t see it, you may need to clear your Windows thumbnail cache. Here’s how to do that:
- Click the Windows Start button and type cleanmgr followed by Enter (or click Disk clean-up when it appears)
- Make sure the Thumbnails check box is ticked at the bottom of the list and then click OK followed by Delete Files
- Go back to Explorer (or your desktop) and press F5
Refreshing the preview image
Each time you change the content in your first non-hidden slide and resave your presentation, PowerPoint will automatically update the thumbnail image. To see any changes, make sure you press F5 back in Explorer or your desktop.
How to turn off the preview thumbnail
Should you decide that you don’t want the preview thumbnail to appear in Explorer, turning it off is as easy as turning it on. Just repeat the steps above and in step 5 untick the Save preview picture check box.
For those of you who want to know what’s going on under the hood of PowerPoint, I’m going to let you in on where the thumbnail file gets created in the Office XML archive. If you don’t know what this is, it’s probably time to grab a cup of your favourite hot drink while we write an article on that! Or you could read this file size reduction article which touches on zip archives.
When the thumbnail image is created by PowerPoint, it’s saved inside the zip archive that makes up the presentation file.
There are several ways to see inside the raw guts that make up a PowerPoint file. You can use the fairly well known method of renaming the file to have a .zip extension or use my preferred method which is to use the free and very powerful 7-Zip application to open the archive without renaming it or having to extract files.
Once you’ve downloaded and installed 7-Zip you can simply right-click on your file and select 7-Zip / Open archive as shown below:
Now you have opened the door to a new and wonderful underworld known as Office Open XML where we can browse and view what makes your PowerPoint presentation tick:
You can navigate the content of your PowerPoint file just as you would with Explorer. To find your preview thumbnail image file you open the docProps folder and there she is, your thumbnail.jpeg image:
Double click this file and you can see it in your associated image editing app:
Going even deeper
Because I like to hack PowerPoint both at work and in my spare time (please send help!) I was curious to know if it was possible to programmatically set the Save preview picture option via VBA (Visual Basic for Applications) which is a programming language that comes with all Office apps.
There’s no API (Application Programming Interface) that allows this to be done but maybe there’s an XML setting that can be changed? Looking at the Word XML file structure, there is such a setting in the aptly named settings.xml file inside a Word zip archive. It’s the element below called <w:savePreviewPicture/>
Curiously, the setting in the Word UI (User Interface) is slightly different compared to PowerPoint in that it appears to be system-wide rather than per-document:
But on checking the PowerPoint XML structure, there is no such setting with that name or any other name. By opening two files, one with a preview thumbnail and one without, I was able to establish that PowerPoint has no XML setting for this and is instead simply checking for the existence of a thumbnail image file and setting the Save preview picture check box accordingly. It’s a pity because that would have made a very nice BrightSlide feature!
So, there you have it. Everything you ever needed to know – and a little bit more! – about preview thumbnails in PowerPoint.Leave a comment
Senior technical consultantView Jamie Garroch's profile
With a dash of patience and a dollop of creativity you can create professional looking assets using just the tools you can find in PowerPoint.
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It provides us with powerful presentation material to use again and again. This helps us get our message across and enhances our professional image.Joe Critchley Trade Extensions