You can display on web pages images from container fields using the FileMaker API for PHP. This is FileMaker Custom Web Publishing. The obvious advantage to CWP is that you do not have to export your data anywhere to display it on the web.
If you want to export the images you have to use the 'Export Field Contents" command which is possible when the container field is selected. This can be done with a looping script which goes to each record and exports the field contents. The trick to doing this is that you have to give the imags a name that will allow matching with the records once again when in SQL.