16 November 2009

Create high resolution 300dpi images for journal publication... in PowerPoint

Update July 1, 2011: Dear users of PowerPoint 2010 and all users of PowerPoint on Mac OSX, due to popular demand, I have created a new post taking into account the limitations of newer versions of PowerPoint. Please refer to my new post on how to create high resolution images without PowerPoint. Users of PowerPoint 2003 and 2007 may use the techniques outlined below.

Not many people know that you can create journal quality, 300dpi, .tif images in PowerPoint. Well, you can.

By default, PowerPoint compresses images and saves them at 96dpi. For most users, this isn't a big deal, but if you are interested in printing the contents of your slides, for example, as a conference poster or as a figure in an academic journal, 96dpi isn't going to cut it.

What is dpi?
Dpi is an acronym for dots per inch, and is a measure of printing resolution. Generally speaking, the higher the dpi, the better the printing will come out.

Changing the dpi setting in PowerPoint
The trick to changing PowerPoint's dpi setting, is that you do not actually change it in PowerPoint.
1. Select Run from the Start menu.
2. Type regedit into the Run box, and then click OK.
3. Once the Registry Editor has opened, navigate your way to the registry key for PowerPoint. This will depend on which version of PowerPoint you are using.

PowerPoint 2003: HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Options

PowerPoint 2007: HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\PowerPoint\Options

4. Select Options by clicking on it once, and then click the Edit menu, then New and then DWORD Value.
5. Type ExportBitmapResolution, and then press ENTER.
6. Select ExportBitmapResolution, and click on Modify on the Edit menu.
7. In the Value data box, type your desired resolution value: 300, then click Decimal (the value will change to 768), and then click OK.
8. Exit the Registry Editor.

Saving a high resolution image in PowerPoint
To save an image, you simply export a PowerPoint slide as a picture.
1. Have the slide that you want to export open.
2. Select Save As from the File menu.
3. In the Save as dialog, select the type of file that you want to export your slide as (.gif, .jpg, .png, .tif, .bmp, .wmf or .emf), and then click Save.

Why use PowerPoint to create images at all?
As I've mentioned before, a lot of people have Office installed on their computers, and universities often provide Office for their research students and staff. Because of its large user base, researchers often crunch their numbers and create their figures in Excel. Importing an Excel chart into PowerPoint is as easy as copy-pasting, and you may then save the figure as a high resolution tiff image, as outlined above.

PowerPoint provides another advantage, which is the reason that many conference posters are created in ppt format. The file may be saved as in native PowerPoint format, preserving the different objects. Need to insert a bigger arrow? No problem. Need to change the font size? Piece of cake. The advantage afforded by PowerPoint is its simplicity. It's easy to send the file to a collaborator, changes can be made, and comments inserted in text boxes.

Further reading
Using PowerPoint to Create High-Resolution Images for Journal Publications