I’ve just been beta-testing the soon-to-be-released version 7 of this product.
The feature I was looking for was the ability to be able to run all my images through it, changing nothing except the dpi weight.
Doing this I managed to take images in a variety of formats from various sources (including a hi-res camera) and create a stream of Jpegs all at 105 dots per inch, and sharpened up a bit too.
The end result was an Images folder that came down from 30MB to 6MB, and an appreciable uptick in image rendering speeds.
Hexagon Global includes this step as standard in its rollout process.
Look out for JpegSizer v.7.0 when it is released.