The invention proposes a method of inserting a message in a subset (VO) of
digital data representing physical quantities, characterized in that it
includes the steps of: estimating (E4) a capacity to receive a message
for said subset, selecting (E5) a message with a size less than or equal
to the estimated capacity, in a set of a messages, inserting (E6) the
selected message in the said subset of digital data. The invention
applies particularly to an object in a digital image.