Given the resolved support map s(x,y), we can now update the statistical models for each blob and for the scene texture model. By comparing the new model parameters to the previous model parameters, we can also update the dynamic models of the blobs.
For each class k, the pixels marked as members of the class are
averaged together to produce the model mean 
, and
their second-order statistics measured to calculate the model's
covariance matrix 
,
This process can be simplified by re-writing it in another form more
conducive to iterative calculation. The first term can be built up as
examples are found, and the mean can be subtracted when it is finally
known:
For computational efficiency, color models are built in two different
color spaces: the standard (Y,U,V) space, and the
brightness-normalized 
color space.