First of all, never use $_POST in 4images, use $HTTP_POST_VARS instead, unless for some reason you need unprotected/unfiltered data.
Second, you'll need specify image_id for each my_check field, like so:
<input type=\"checkbox\" name=\"my_check[".$image_row['image_id']."][]\" value=\" size photo does not comply;\">
Then, you can retrieve the data with something like this:
foreach ($image_list as $key => $val) {
$note = "";
if (isset($HTTP_POST_VARS['my_check'][$key]))
$note = implode(" ", $HTTP_POST_VARS['my_check'][$key]);