²While this is an all encompassing statement, reality says that it can only be smaller if we throw information away. If the image is already at its smallest, then nothing can be saved. However, this is rarely the case. In my case, I shoot everything in the NEF format and they are many megabytes in size. Saving a thumbnail and 900x600 representation is a 10x savings in space. Now I can store 10 years worth of pictures on my local file system instead of the single year with NEFs. However, if your picture are already 900x600, then it is hard to save any significant space.