I know I can do that, but the idea is that I have a cron script that runs once a day that will convert it for me - much easier than downloading a 3mb file, converting it and uploading it.
This may not be exactly what you want but I've done something similar in the past.
Using libgd (Current stable version is 1.8.4 found Here, although its usually included with most Linux dists thesedays) you can write out JPEGs PNGs and build them using C. Previously I produced a weather map (I had weather formations and stuff like that) which recursed quickly through the overhead map and built a graphic colouring the pixels. This file I then served via the internal web server I wrote.
Two problems with this, one, I don't think it works with RAW image files, although as Samson imports via AFK, I assume there is code to read it in, using libgd, you can write them out again, two, your overland may be a bit large to periodically write out these graphics but in which case you can create a seperate little prog (using the RAW import and libgd output) to do the job.
Bleugh, also just realised.. (*runs off to check some info*)
Another REALLY easy way.. bunch of tools called Netpbm. Just checked, will convert from RAW to its native and then to another format (says it has about 88 formats supported I believe so it should be able to do what you want it to). A small script and those tools should also be able to do the conversion you want.
Hopefully some of that is useful.