How to rip PSP isos

There are plenty of posts asking how to use ISOs on the PSP, but I couldn't find a single one which explains what software is used to actually rip the image from the UMD. I want to back up my collection and I'm simply unsure how to do so.
(PS. I already know that a downgraded PSP is necessary, that's not the issue).

Do you have a memory stick? Here's a guide but you need a memory stick. http://dukespspisos.forumotion.com/tutorial-section-f185/guide-how-to-rip-your-umd-games-t937.htm