...Just read you JPEG and add an alpha channel manually, then assign values for transparency. Of course for printing you need to use a device that accepts alpha.See how it's done HERE.
Here’s a bit of code used to produce one of the figures in my recent paper dealing with modeling rocky intertidal snail body temperatures. This was my first foray into ggplot2, and it only involved a few hours of head-scratching. The plot is a co... [Read more...]