Access imagefield file object during node create/update
Even if the field hasn't been updated yet you should have access to the fid column (the file ID), which you can use in conjunction with the file_load() function to get the filename:

// Load a file object based on the fid column fo the field.
$file = file_load($node-&gt;field_foo_image[$node-&gt;language][0]['fid'];

// Get the filename.
$filename = $file-&gt;filename;