We initialize the lookup table by setting all entries that have exactly
one physically meaningful solution, and fill the remaining entries
using a smooth membrane interpolation. This is accomplished
by iteratively replacing every entry by the average of its six neighbors
(“Laplacian smoothing”). The smoothing is performed in a
coarse-to-fine manner. Computing a 1003
lookup table takes about
a second. Once the table is complete we use it to convert each of
the pixels in the input RGB scan. An example color separation is
shown in Figure 5.