Resize images on entire drive

[Don Manuel]

Welcome at our mainly German speaking board. I am sorry to tell you, but you won't find too many ppl here reading or even answering English. I do, so let me give you a comment:
Your idea of saving a few GB by resizing truly makes no sense with given HDD-prices. Any resizing means a loss of quality, aside of time and the risk of data-loss. So invest a little in the safe storing of your full data and forget about this resizing job.