s[[] Is Ie e[]] Js Ie Is Je Js

Picture rotation considerations for contouring algorithms are straight forward. Equation ( 11) for the 9-point bi-quadratic interpolation algorithm is still valid after changing the Qk({) functions as follows:-

for kr = 1,3 (13)

in which k = -1,0,1, s = (-k)¥ and t = (-k)hfl. A similar formulation can also be applied to the 4-point bi-linear interpolation algorithm.