Most images, jpg, png, etc, are visible directly in most modern browsers.
If you have images that are not visible directly, look for filters for those formats to convert from whatever you have to a web friendly format. Also consider using a "thumbnail generator". As you know, a thumbnail is a compact edition of an image that is very web friendly.
The linux world is full of utilities with names like mumble2pdf
. There are also numerous filters with names like mumble2ps
. Where "mumble" might be "text", "ps" (postscript), "doc", "html", "man" and so on. You will need someone to create scripts that accomplish the command line conversions for your server.
Conversion on demand sounds like a good idea at first, but I would discourage that approach. It is too easy to store files in a compressed archive that you uncompress on demand. Thing about a very large DOC file -- a dissertation or other white-paper. Do you really what your site visitor to wait while it converts before they can read it.
- Accept documents uploads in whichever formats make sense
- Convert on receipt or batch them up,
- store as PDF to a separate folder
- compress the folder contents to save space