I suspect that if all you are doing is an after the fact lossy compression, you can probably find something out there that is free. I've seen websites where you upload the picture and it shows you different compression options. I think linux has a built in graphics editor that can do this. There are probably other tools as well. Check out download dot com and see what can be found. If that's all you need the software to do, there is little reason to burn $100 on a brand new PSP or $400(or whatever ghastly price its at now) for photoshop.