performing GMM on PDE (probability density estimator)

I have intensities map which I want to model as a sum of gaussians using GMM method. However, this map fits the probability density function of the GMM, while the built in matlab code gmdistribution.fit receives input which is a realization of that pdf. I can bypass it somehow by using that pdf to create a set of samples to be sent to the mentioned code, but that's a distorted way. Can I make Matlab have the pde as an input?