Automatic Jpeg compression

[The late XV105]

Background:
For reasons of reliability I have recently switched backup tools. Given that I do not need encryption, a nice side effect is that whilst the backups in question are still net change (so fast and near real-time, with full backups being taken periodically via separate means), they are also now a simple file copy, including structure. In other words I get a "plain" copy of the source that acts and looks identically. No encryption or funny control files beyond an XML master file at the same level as the root. This is working with total success.

Question:
Do any PPRuNers have experience of a Jpeg compression tool that can be run automatically when a file is received in a given location?

Reason:
In addition to my backups I currently maintain on my networked NAS a copy of my entire Jpeg photograph library in compressed format (typically 1280x1024 at 100kb per photograph). This is done for ease of on-demand e-mailability and swift next-next-next loading when browsing on my wife's 802.11g netbook. I will now use the new net-change "backup" tool to maintain this directory automatically but currently will still have to manually initiate compression. This is very easy using the excellent picture resizer from rw-designer.com to recursively scan the entire structure and batch compress where required, but the purist in me doesn't like that the HDD gets used for a full scan when in reality only a handful of files out of many (currently over 20,000) have changed.

TVM,
XV