I am looking for an online application that can be locally hosted which will allow authorized users to view PDFs stored on a local file system, redact the areas in the PDF that contain sensitive information, and save the updated PDF back to the file system.
Since all of the PDFs were created from scanned documents (aka they are just images of documents) it's OK if the PDF is converted to an image, edited, and converted back to a PDF.
We cannot use any remotely hosted services, we must be able to set it up on our internal web servers (Windows/IIS or Apache or Linux/Apache). Prefer the app to be PHP, Perl, or Java (in that order).
As far as building our own. We know how to convert a PDF page into an image, display the image on a web page, and draw solid black rectangles (aka div elements) on top of the image (keeping track of the x,y coordinates). We are stuck on how to take those coordinates and actually modify the image file adding the solid black areas using the coordinates obtained. From there converting the image back to a PDF is a simple task.
If anyone has any suggestions for a pre-built app or for rolling our own I would greatly appreciate it.