@INCOLLECTION{WFWBB05,   author = {J. Weickert and C. Feddern and M. Welk and B. Burgeth and T. Brox} ,   title = {P{DE}s for tensor image processing} ,   editor = {J. Weickert and H. Hagen} ,   pages = {399--414} ,   month = {January} ,   year = {2006} ,   booktitle = {Visualization and {P}rocessing of {T}ensor {F}ields} ,   publisher = {Springer} , }