I think you are referring to the aperture software.....with that being the case, you have minimum file size only after the original file is created.

That being said, if you make a color adjustment with, lets say, hue or saturation, you only create a very small file that performs that adjustment from the original file.

So in reality, what you have is a data base filled with only "negatives" or "original files". All of the different adjustments and versions that you create from the original are only minute command files, taking up hardly any space. As apposed to creating an entire new picture and saving it again for each adjustment and each version, as with PS. Those who have used, or are using PS clearly see their memory diminishing very quickly with each new saved version.

I hope that helps clarify what I was attempting to state.

TM