Microsoft Powerpoint has, regrettably, not only become the default program for doing presentations is probably also the most common program for making posters (with the possible exception of Microsoft Word which is even less suited to the task). Also regrettably both academic & business posters are, these days, usually judged more on flashy appearance than on content. These two requirements are not very compatible because Powerpoint was only really designed for bullet point presentations. Even if one is used to producing on-screen presentations in Powerpoint, different tricks are needed for overcoming Powerpoint's faults when printing.
Of course, professional artists & graphic designers have far better programs for drawing, typesetting and rendering posters. If you are one of those then stop reading this and stick with those programs. Unfortunately the rest of us get stuck with Powerpoint, either because it is the only vaguely suitable program which comes bundled with most office computers, because it is corporate policy to use it or because one has been given a template or background in Powerpoint format. When I first tried producing a high quality conference posterboard in Powerpoint, I found numerous problems. The following is based on tricks I found to get around them. This is an addendum to my previous article "How to do Powerpoint Animations". That article is more comprehensive and covers, as well as animations, advice on basic Powerpoint use and adding graphics. Those bits should be read before reading this unless you are already familiar with the tricks for producing tidy on-screen graphics in Powerpoint.
In the following I am referring to the 2000 version of Powerpoint (the 97 version was probably similar but any versions before that are inadequate for image importing) for M$ Windows (I expect other platform versions will be similar except that commands might be in different menus). Later versions will probably have the same features plus some more but, even so, it is good practice to only use the oldest set of features that do the job because (a) those are most likely to have been debugged, and (b) the presentation should still work when saved as an older file type lest you have to use it on a system older than your own.
When making posters, different tricks are needed get around the deficiencies of Powerpoint from those needed for on-screen presentations. Some things are much easier. For example, there is no worry about whether animations will work or not in the live show; once a poster is printed, it is complete and safe from further Powerpoint bugs. Neither does it need to work on other people's computers (although if it does so then it is more likely you will be able to edit & reuse parts of the poster on your own future computers).
However there is one big snag: the resolution required is much higher. A typical computer projector screen is only 1024 dots across whereas even a 1 metre wide poster at typical 600 dpi printer resolution is about 24 000 dots across. The picture quality needs to be much better to avoid looking scruffy, especially if people can get close to it.
For photographic, & other bitmapped, images the solution is conceptually simple - just use higher resolution copies. This inevitably increases the overall file size but that is not so much of a problem as for on-screen presentations because you only need to ship the print-out eventually, not the original file. Even if you are using an external print-shop to produce your posters, they are used to artists with little underlying computer conceptualization sending them absurdly huge files so, as long as you have a fast network connection or a CD-writer then this is not much of a problem. Even so it is best to experiment with different resolutions and compression methods to prevent the file being unnecessarily large (e.g. an image that works on-screen with a 15 Kb file might need a 200 Kb file for printing but probably not a 30 MiB one as I've had one artist send me) as it may cause the programs and printers may run annoyingly slowly.
A more serious problem is that requires one to have the original images in high resolution in the first place. You may have to go out photographing or rendering again if you did not keep (or make) high resolution originals
Vector images are ideal for posters because they can be blown up to any size and printed at full printer resolution giving impressively sharp lines & clean solid colours with no redrawing effort and no increase in file size.
Unfortunately, the vector drawing facilities in Powerpoint itself are very primitive and importing pictures from better vector drawing programs, like Corel Draw, Adobe Illustrator or Macromedia Freehand, into Powerpoint without converting them into bitmaps (which would loose the ability to enlarge them neatly) does not work well. Powerpoint treats them as embedded editable objects, which cause problems if they are then transferred to a computer without that particular editing program. It also uses a bitmap copy of the images for display anyway, which does not rescale well and vastly increases the file size.
One solution is to use EPS as an intermediary image format. EPS, Encapsulated Postscript, is a version of the Postscript printer command language adapted for use with individual images rather than whole documents. Most good vector drawing programs should be able to export directly to EPS retaining the image in a vector form (if yours does not then you can still produce EPS in a manner similar to how one can produce PDF files). EPS images can be included in Powerpoint in the same way as normal JPEG & PNG images whilst retaining the vector ability to expand to any size at full resolution when printed.
As expected with Powerpoint, its EPS implementation is faulty. In particular, it cannot render EPS on-screen, only when printing to a Postscript printer, so an EPS image is not good for on-screen presentations. Powerpoint only uses the preview bitmap version of the image that is embedded in the EPS file. The preview image is not normally compressed well and, of course, does not rescale well. The embedding of a preview in EPS is optional so, if you do not mind not seeing the image on-screen whilst editing in Powerpoint, you can make the file much smaller by missing it out entirely. I personally used a compromise of a very low resolution embedded preview image to remind me what it the image was.
That EPS fault in Powerpoint unfortunately implies that separate versions of the Powerpoint presentation need to be made for printing & on-screen display if one wants both looking smart.
Remember that it needs a Postscript printer for Powerpoint to correctly print EPS as Powerpoint cannot render EPS itself. If printed on a non-Postscript printer, the images will be the scruffy preview ones or completely missing. To avoid this problem, take the whole presentation/posterboard and convert it into Postscript or PDF before printing. This will also allow you to print it from a computer without Powerpoint installed and makes it safer when sending for someone else to print as it avoids the risk of their version of Powerpoint rendering it differently.
Print a test sheet first to check the colour rendition on the printer is how you expected (or better) and adjust the settings in the printer drivers if the colours come out wrong. Remember that the colour capabilities of ink are not the same as a computer monitor. The monitor can do real real glowing colours which the printer, using reflected light, cannot but ink can give a much fuller colour range, in particular in the depths of dark colours, giving possibilities of a richer & more realistic appearance. Choose your poster & on-screen colour schemes accordingly.
One also needs to choose how to mount the poster and what shape to make it. The most popular mounts are:
The shape of the poster is a risk unless is sure in advance what size the space is. If one brings a short wide poster and finds that the display stand is tall and thin then fitting it is going to be rather difficult and/or ugly. A work-around is to make the posterboard out of several separate smaller sheets which can be arranged as needed. This also has the advantage that one can fit it in one's rucksack or suitcase rather having to carry a large awkward separate document tube or folder.
Yet another catch is that Powerpoint, by default, prints at screen aspect ratio & with a thick white border. To remove these two unwanted features, change the paper size in Page Setup to the one with the same aspect ratio as the printer paper and set it to "scale to fit" the paper in the printing dialogue box respectively. Both these options are (of course!) badly implemented in Powerpoint. Changing the aspect ratio causes Powerpoint to attempt to squish the background images in the Slide Master to match, which typically looks a mess so one has to delete the corrupted background artwork, copy the original back in from an unaltered copy of the Powerpoint file and then manually adjust it to fit. As for the scaling to fit printer paper setting, this setting is often forgotten by Powerpoint so remember to check it is still set each time before printing.