Bill,
I may have an option for you here
Currently there is no way to do this directly with PM. I however found a great work-around: use the export function. Take, e.g., PM Classic. With the export you can specify quality, size, etc. of the images exported.
There are a few disadvantages to this solution of course, but with a little bit of scripting yourself you can circumvent these. The major problems (I see) are:
1. Thumbs and html-files are generated as well, resulting in a lot of clutter and extra overhead.
You can get around this by editing and amending the ruby export script and/or create your own.
2. Image files are called xxxx.yyy.jpg (where xxxx.yyy is the original file name)
A little command-line scripting gets around this.
3. Files get dumped into one big directory (images and thumbs).
Again not too difficult to solve with a bit of scripting and/or drag and drop.
Hope this helps,