Gnuplot and Powerpoint (and other presentation software)

• The fonts used are often so small that they can't be read from the back of the room (sometimes even the front).
• The line width is so small that sometimes a horizontal line will not be visible on a projector that does not have very high resolution.
• The default colour choices are poor (the default yellow is usually not visible).
• In many cases the default choice of point types make it difficult to distinguish points from different lines. E.g., the +, x and * are the first three characters used. If a + and x appear in the same location you can't distinguish them from a *.
• Powerpoint doesn't do a good job of including encapsulated postscript files (eps files). Sure it works, the graph appears but the resulting output is of very poor quality (lots of jaggies).

This note describes some steps you can take to to produce better quality graphs that can be used with Powerpoint (and likely other presentation software).

Here is the approach that I've used. Some of this information comes from Martin Arlitt.

• Use gnuplot to generate an encapsulated postscript (eps) file. Be sure to increase the linewidth, border width, and font size so that they can be seen when using an overhead projector. I actually use a slightly modified version of gnuplot that does (in my opinion) a better job of picking symbols, colors and when generating black and white versions for papers line types (e.g., better dashes, dots, etc.).
  Here is a gzipped tar file of a modified version of gnuplot-4.0.0
  Here is a gzipped tar file of a modified version of gnuplot-3.7.2
  Here is an example gnuplot input file.
  Here is the input.txt file (data) used with the example.
  Here is the resulting eps file (example.eps)
  Here is the resulting eps file converted to pdf (example.pdf)
  
• Use "convert" from ImagemagicK to convert the eps file to a jpg file.
  Options I've found that work pretty well:
  % convert -density 1200x1200 -quality 100 example.eps example.jpg
  Note that the density is very important. Lower density produces relatively small graphs that when enlarged in powerpoint look very poor/fuzzy.
  Here is a Makefile showing how to do a number of different conversions
  Here is the resulting jpg file (1252255 bytes) and very large.
• In powerpoint "Insert -> Picture -> From File ...
  
  You can insert the file directly. This should produce a powerpoint file that is fairly portable, but probably quite large. It also means that anytime you change the the gnuplot produced graphs you need to reinsert the new version of the jpg file.
  
  Or once you've browsed and selected filename.jpg click on the little down arrow on the right side of the "Insert" dialog box. Then select "Link to File". If you change/update filename.jpg those changes will be seen the next time you open the powerpoint file. However, this doesn't seem to be very portable because it looks like it tracks the file by the absolute pathname :-(. So if you create the presentation and store the files in d:/talk on one machine you need to ensure that it is in d:/talk on the machine you use later.
  
  I've used gnuplot and the ImageMagicK software under Linux and Cygwin.
  
  
• Here is a powerpoint presentation with containing the jpg and eps versions of the graph.
• Here is an Open Office presentation containing the jpg versions of the graph.

You might want to try png