PHP Code:
<input type="file" name="picture_name" <?php echo $image_name; ?> >
You can't enter your own values for the input file name for obvious security reasons.
Otherwise people could send all sorts of malicious code to the server.
You can get the original filename to enter into the database from
$_FILES['txtUploadFile']['name'] where txtUploadFile is the name of your file input box.