I'm not sure you would see much benefit to compressing image files anyway - most formats are reasonably compressed already.

I do have a case where we are capturing and storing reports as TXT files from an ERP system.  We have TONS of those files, and raw TXT files compress very nicely.  

Instead of using any compression in Laserfiche, we used the Windows folder compression.  (Right click on the volume folder in the filesystem, click Properties, then Advanced, Then "Compress contents to save disk space")  

One example volume - around 750,000 files - I see a 1.52:1 compression ratio, which will save us significant space.

Windows handles the compression, Laserfiche doesn't care, and we save on disk space.