Focus on PowerPoint printing

The curse of PowerPoint presentation printing

Everyone who runs a print center comes to despise PowerPoint and the people who make PowerPoint presentations available for printing. What's the problem? LAYERS!!

A feature of PowerPoint is the ability to create slide content by means of a set of layers. You may lay down a background image as one layer, then import a bunch of images for the slide on one or more layers, and then place text over all that imagery on a final layer. A college instructor will do this, and then do Save As to create a PDF of the presentation for the class to use. All seems well and good, where the PDF will consist of page by page images generated from the presentation, right? Wrong!

When a PDF is created from a PowerPoint file, the PDF does not consist of static image pages generated from each page of the PPT: the PDF carries all those complete images along, where each layer's content is fully included. When you view the PDF in a browser or like software, you see what looks like a final image of each slide, but that is misleading. Printing that PDF usually entails generating a PostScript file from the PDF, when then goes the printer. The PostScript file likewise carries all those layered images along, in their totality, for processing. This, of course, results in a very large file (e.g., 180 MB) which then takes considerable time to transmit and process. Far, far worse is that the PostScript interpreter has to render each page's final image from all the layers data. In effect, the PostScript interpreter has to play back each page's content in order to generate the page's final image. This involves rendering the full background image, then overlaying that with the content from each upper layer, in turn. The required processing can be seen by running the Ghostscript 'gs' command on such a PostScript file, where you will see all this image generation and overlaying going on until the final page image is produced. This is horrendous waste, in spending a lot of processing time generating imagery that will be at least partly overlaid by further page elements. Moreover, in many cases the background is elaborate, high density color imagery which takes considerable time to render.

This situation is often made worse by a PowerPoint author who either doesn't pay attention to what's in the layers or doesn't care, "replacing" some old text or image not by actual replacement, but instead by creating new content via a new layer which overlays old content in a now-lower layer, thus adding further bloat and processing time to the print processing.

Microsoft neglects to provide a capability in PowerPoint for the merging/flattening of images and layers.

What can a PowerPoint author do to make their creation efficient?

• Do not use elaborate background images: that's poor practice in general. "Busy" background images are distracting and make text hard to read. A solid color background usually makes the most asthetic sense (see Apple keynote presentations). If you absolutely feel compelled to have a background image, make it subtle and simple, such as gradient gray.
• Minimize the use of images: people often over-use images simply because they can, even if that makes for superfluous content which detracts from conveying the information that is the presentation's purpose.
• Minimize the use of overlapping images: use smaller, non-overlapping images.
• If you go to change content, actually replace it: do not put another layer on top of the old stuff — which only leaves your possibly embarrassing old stuff still present in the file. Cycle through your layers to assure that no obsolete content is still present.

Do a Web search on "powerpoint best practices" for more guidance and tips.