I can't really give an answer since I lack experience on the subject but there is research done which might be helpful for your inquiry:

Weidong & Zhang - A Generalized Markov Chain Approach for Conditional Simulation of Categorical Variables from Grid Samples

http://gis.geog.uconn.edu/personal/paper1/journal%20paper/10%202006%20transaction%20gis_1017.pdf

Weidong - Markov chain random fields for estimation of categorical variables

http://link.springer.com/article/10.1007%2Fs11004-007-9081-0#/page-1

Hope it helps.