  A well-known old adage says that {\em "A picture is worth a thousand words!"}
(attributed to the Chinese philosopher Confucius ca 500 years BC). But more
precisely, what do we mean by information in images? And how can it be
retrieved effectively by machines? We briefly highlight these puzzling
questions in this column. But first of all, let us start by defining more
precisely what is meant by an "Image."
