this would require hand coding using the file_exists() function:
function.file-exists.php
for example:
<?php if (file_exists("path/to/images/".$row_recordsetName['imgColumn']."")) { ?>
<img src="path/to/images/<?php echo $row_recordsetName['imgColumn']; ?>" />
<?php } else { ?>
<img src="path/to/images/default.jpg" />
<?php } ?>