This paper introduces a novel approach to visual data compression. The
approach, named dynamic coding, consists of an effective competition
between several representation models used for describing data portion
s, The image data is represented as the union of several regions each
approximated by a representation model locally appropriate, The dynami
c coding concept leads to attractive features such as genericness, fle
xibility, and openness and is therefore particularly suited to a multi
media environment in which many types of applications are involved. Dy
namic coding is a general proposal to visual data compression and many
variations on the same theme may be designed. They differ by the part
icular procedure by which the data is segmented into objects and the l
ocal representation model selected, As an illustrative example, a vide
o compression scheme based on the principles of dynamic coding is pres
ented, This compression algorithm performs a joint optimization of the
segmentation (restricted to a so-called generalized quadtree partitio
n) together with the representation models associated with each data s
egment. Four representation models are competing namely, fractal, moti
on compensation, text and graphics, and background modes, Optimality i
s defined with respect to a rate-distortion tradeoff and the optimizat
ion procedure leads to a multicriterion segmentation.