Which is the reason to use Image Handler and is explained in the readme..

Quote Originally Posted by ScriptJunkie View Post
IH2 takes your original images and makes optimized and resized copies of them and stores them in the bmz_cache folder. It leaves your original images untouched.

So, if you delete image copies from the bmz_cache folder, or clear the folder altogether, nothing happens to your original images. However, next time the page is loaded, copies of the images will be once again placed in the bmz_cache folder.

Every time that page is loaded in the future, those image copies are served up from the bmz_cache folder, ensuring that your pages load faster (because the image copies are optimized and resized according to the IH2 configuration settings you specified when you installed IH2).

Suggest you download the IH3 installation package (it has a better READ_ME file) and read the first tab of the READ_ME...which explains what IH is and what it does. This might help you have a better understanding.

Good luck and happy Zenning