edjpgcom is a free Windows application that allows you to change (or
add) a JPEG commment in a JPEG file. That's all it does. All other
fields in a JFIF or Exif file are left untouched. It even keeps the
filesystem timestamp! It's based on the rdjpgcom and wrjpgcom
utilities from the Independent JPEG Group's 6b distribution. (Heck,
it's essentially these two programs combined with a basic dialog
control.)
1