## Differentiating in the discrete domain

Hi,

I need to minimize the following function. g and b are two dimensional functions of independent variables i and j. * represents a CONVOLUTION. lamba1 and lambda2 are non-negative weights.

Also, is it possible to solve its equivalent continuous function? i.e. with the summation replace by two integrations and having g and b as continuous functions.

Thanks a whole lot in advance.