Very large scanned images take up a lot of space in the "comments" table. This tool goes through all scanned images attached to comments, certifications and background checks, looking for images which are larger than the size you specify. Run it specifying the maximum width and height for scanned images and VSys will go through all images which are too large and resize them.
This is not a fast process and may take a while to process, especially if you're on a slow network connection or the drive holding the data is slow.