[Zope] image processing site quidance...

Hello Zopistas, I need a little guidance for a site that must make image processing on the fly. Users should be able to upload image files and after some pixels manipulation they should see the image preview after the changes and download it. I have installed PIL successfully for that reason (thanks to smiley Chris) so I can use it as an external method. I have thought to do this implementation uploading the file to the ZopeDB and change it there or should the file be uploaded in the local file system ? either way , what should I know so I can do that ? thanks in advance.