Get the picture

Photos are amazing things and I'm sure that many a treatise has been based on then. But have they been based on the original - as in unedited - version or on the effect after the pic has been through some photo editing software? I used to be a puritan about not editing pics but somewhere over the last while I seem to have lost that - as I noticed this evening as I cropped and adjusted the contrast/brightness of a plc taken with the iPhone and really in need of some help. The only problem was working out which software to use - even though I had been determined not to use one, I had kept downloading programs - just in case!