We discuss quantitatively the problem linked with the fractal and mult
ifractal characterisation of complex real systems from image analysis.
We have used a model of early spinodal decomposition introduced by Ca
hn. This model, although resulting from a purely random process, conta
ins a characteristic length scale lambda. Using the classical box coun
ting method, we have studied the scaling properties of this system whi
ch is by construction a non-(multi)fractal object. We show how in that
case a blind use of the box counting may lead to a spurious (scale de
pendent) multifractal curve and how the more general scaling of the in
formation entropy in the cross-over region around lambda can provide a
method of characterisation of the morphology of the model.