My personal files are growing in space requirements, and much of the space is occupied by my photos. They are typically in the 4 mb range. Yesterday, I DL'd a resolution changer tool and it worked very well--perhaps too well. I set it to reduce the resolution of all the photos in a particular folder by 50%. Properties suggest that the new images (written to a new folder) are indeed 50% lower. However, the sizes (on the hard drive) are now minuscule, like a couple of hundred kb's. How is this possible? When I compare the new and old images visually, I don't see any difference, which is a good and encouraging thing. I'm reluctant, though, to trash the original, larger-resolution photos for fear I will have forever lost critical clarity I might want for some application.
My questions are:
1. How does reducing resolution by 50% result in reduction of space requirements by 85-90%?
2. If I can't see (visually) any difference in clarity, is there a possibility that a stark difference may appear when using my photos in some application in the future, say when printed or converted to some other format?