How do I convert an image?

[True Federalist (진정한 연방 주의자)]

I know how I'd do it.  I use IrfanView as my image viewer/converter, So I'd load it into IrfanView and then save it as a *.jpg.  It's freeware, so other than the time it takes to download it and install it, there's no cost, but you may already have a program that can do the same.