Star Dog,
All depends on what you want to do with that image over time. First, I never get rid of original images unless they are badly streaked or have other massive defects. The same goes for my flat, dark and bias subframes since you may want to be able to reprocess masters for matching lights at some point in the future. I learned that the hard way since I did not save those subhframes when I was using other software and now cannot reproduce quality PI standard masters for my old data sets.
For processing images, I always at least save my latest effort because I may want to go back in the processing sequence and tweak something I did earlier. This is especially true when new tools come along, which happens all the time in PI. It saves having to go all the way back to the beginning if you have saved along the way and identified the steps you took each time in the name for that step in the process.
Of course, you are right that this gets to be a load of data. But hell, you can pick up an external TB hard for next to nothing these days so that shouldn't be the driver for your decision.
Best,
Jim
