Huge PowerPoint files and how to avoid them

I have used PowerPoint for many years in a variety of job roles and it never ceases to amaze me that other people are able to create presentations which are, quite frankly, vast in their file sizes. There are several reasons for this, but the underlying problem is twofold:

a) users don’t think about file size until it is too late (when they realise they can’t email it, nor fit it on their memory stick nor even burn it to a single CD)

b) they don’t know how to avoid or fix the problem even if they did think about it

This means that many common causes of over-sized files go unchecked, files are used and re-used, and by the time you see there is a problem you have a huge clearing up job to do. Much better to tackle the issue at the source – when creating your presentation in the first place.

A picture is worth ten thousand words

… and most of them will be expletives if you don’t handle your images properly.

The most common culprit I see in my training and support work is often over-sized graphics. Having been involved in a games development company for a while (back in the good old DOS days) I had to get to understand different file types, pixels and colour depths and the difference between vector and bitmap graphics. However, many PPT users simply do not have this background, and have grown up in a generation with huge disk capacities, fast processing, streaming media and multi-megapixel digital cameras. They have learned to be complacent about images because their normal experience is that their hardware can handle whatever is thrown at them.

Seeing the whole picture

I once had to provide support for a user who could not understand why the picture she was inserting simply did not insert when she pressed OK. It took me a moment or two to see that the picture object was in fact created, but it could not display the image and had replaced it with the infamous ‘red X’. The reason this took me a second to spot was because it had been inserted at full size, much larger than the slide itself and the red X was way off the screen so all we could see was white (which was also the slide background colour). The picture border only came into view at about 25% zoom. This was an original, full-size professional product shot taken on a high-end camera with almost no compression. The JPEG was about 30MB! She wanted to scatter about two dozen such pictures on the same slide, postage stamp sized. Sanity prevailed, I resized the images to a few hundred pixels square and then gave them back.

When trying to explain the issues to people, the other stumbling block is of course trying to get them to grasp the difference between a megabyte and a super-sized burger. So I tend to use a much simpler approach through analogy:

If you look at the Eiffel tower from further away, you do not actually believe it has become smaller or has any less steel in it, or is any lighter, do you? If you wanted to share your enjoyment of it with someone you know you could not send it by mail, even though it looks quite tiny when you stand far away. So what do you do? You get a much smaller copy of it from a souvenir stall and send that instead. You might lose some of the detail of individual rivets, but the recipient gets the sense of the thing.

So, take a copy which is smaller than the original (by resizing before inserting the picture) and deliver that (via the presentation) instead.

It’s not too late!

Say you already have a finished presentation with lots of graphics in and it’s too big to get on that CD to send to your client. You maybe don’t want to go to the hassle of zipping the file to make it smaller (or don’t know how) and that would annoy the client anyway. So what can you do to make it smaller?

Rather than remove and re-insert your images (many of which may no longer be available if you are using generation 27 of this file anyway) you can simply edit the ones you have, very easily.

Select an image, Cut it (Edit > Cut, or CTRL-X as a shortcut) then use Paste Special to get a choice as to how to put it back in. You need to select an appropriate type depending on what sort of image the original object was. This is very simple:

  1. for photographs always use JPEG. JPEG is a format specifically created to store photographs at the best quality for least size.
  2. for things which are drawings created in an MS Office application, which have lines, boxes, curves, coloured areas etc (such as a chart, org chart, or set of drawing objects), choose “Picture (Enhanced Metafile)”. This will allow you to continue scaling the whole thing later without too much loss of image quality
  3. for everything else use either GIF or PNG. Personally I always choose PNG but the difference is almost zero.

PowerPoint will then make make your images smaller as necessary – if you check the pasted object’s format you will see that size is exactly 100%. So if you scaled down a large photo to 25% this was like walking further away from the subject, but now the new copy of the image is this smaller size and would take up about 1/16th the filespace. PowerPoint has thrown away unnecessary detail that you can’t see at this size, as well as any cropped parts.

You can take this one step further if you have several drawing objects on a slide – by selecting them all at once before cutting and pasting back in as a picture you don’t have to group them together, they just work as a single object and can be moved and scaled as one. This does mean you can no longer animate them individually (which is probably not a good idea anyway if you don’t want your slide to be too ‘busy’) and if you stretch the image any lines / arrows / box outlines and so on will get thicker as well as longer (unlike a true drawing object which retains consistent line thickness).

Don’t try this for mixed types of images such as photos and drawing objects as you will not get the best result for any of them. Also avoid it for multiple photos as you will probably end up with a big black rectangle showing through all the gaps between them; simply do them all individually.

In PowerPoint 2003 and later you can also run the optimisation wizard to get it to resize one or all of your imported pictures in a presentation and this will have a similar effect, although it won’t select multiple ones to turn them into a single object.

File format myth busting

I have had people say to me that they have heard GIFs are always smaller than JPEG, or vice versa, or that you have to use GIFs for websites and JPEGs for everything else (who makes this stuff up?). If you save a photograph as a GIF file it will not only tend to look worse than a JPEG equivalent, but may well be significantly bigger in filesize. If you save a block-colour image as a JPEG it will have mottled areas and other artefacts which reduce the quality (particularly at larger scales), and again will often be bigger. GIF and PNG are good at making repetitive, flat-colour images very small. Anything which is supposed to have areas of flat colour, such as a company logo, will always be better off as a GIF or PNG. Anything like a photo, or a scan of a photo, is best off as a JPEG.

Charting your success

The other common problem I see is people using embedded objects such as Excel spreadsheets in order to display information – a monthly sales chart for example.

I have nothing against OLE when used correctly for it’s intended purpose, but again the problem arises through ignorance because people want to achieve a goal and not understand what is really going on.

A typical scenario will be that one person (or team) produce figures, such as sales reports in Excel, and add a chart to make the information easier to digest.

Another person wants to use this chart in their presentation in order to make their slide have more impact and be easier to take in than a whole table of figures. Good plan so far.

What you see is (not) what you get

So they open the spreadsheet, select the chart object, hit copy, go to their PowerPoint slide and hit paste. The chart appears where they asked it to be and the goal is achieved. However, all is not as it appears. What happens when they then double-click on the chart? They get an instance of Excel and can actually edit all the original content of the spreadsheet, because this has been embedded in the slide now – and if the spreadsheet was several megabytes in size, then so is this slideshow now.

This is not what they intended in most cases, but it is what they get. The chart appears to be simply pasted, so the user believes they got what they wanted. There is a real risk that the underlying data may be commercially sensitive, highly confidential or contain some form of personal information. If this is emailed out to someone, then the potential risks to your business are huge.

What people really want to do in most cases is to paste the chart on its own. This is very simple to do just be going to Edit > Paste Special and choosing to Paste as a picture. The same applies if you want to paste a table of data from Excel although that would be much worse from the point of view of creating a clear presentation.

Less (clutter) is more (impact)

Something to bear in mind is that many default Excel charts can look quite cluttered once included in a presentation. Think about removing the background colour (usually a dull grey), the tick marks on axes, data labels, maybe even the legend if it is redundant. Anything you can do to reduce the amount of things people have to take in will help them to concentrate only on the important part – the data and it’s meaning.

To see a great example of the difference between an overblown 1980s-style chart and a stripped-down, streamlined, minimalist corporate look with much more impact take a look at this PDF file of a chart being stripped down on the Hichert website. If you view this so you can see a full page you can use your mouse’s scroll wheel to really see it being stripped away as you flick through the pages.

More resources

If you want to see why a particular presentation is particularly large, then this SizeMe addin from Bill Dilworth, MVP is a great tool for PowerPoint XP (=2002) and 2003 (and a version for 2007 coming soon).

PPTMinimizer is a great utility for reducing the size of one or more PowerPoint files. Really great value, and you can even download a free limited-use demo version to try it out.

This article on PPTFaq goes into a lot more detail about the problem of PowerPoint file bloat and some possible causes and fixes, including the effect of enabling / disabling fast file saves.

2 Responses to Huge PowerPoint files and how to avoid them

  1. graycat says:

    For really big presentations that have to be e-mailed out, I find a simple Right Click on one of the pictures, hit format and then “compress pictures” works great. Well, only on Office 2003 and late of course 😉

  2. Adam Vero says:

    Thanks for the input!

    That can be useful (as mentioned in the article) but if you have fast saves turned on it can leave the file at the bloated size. Ultimately, it is best practice to resize images before they get anywhere near the slides themselves, and if th original and reduced images are well-managed then one person can resize them and every other user benefits rather than having to repeat the effort of doing this.

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