1. A system for generating an interpolated value at a first interpolation point between two central source points of a set of four source points, the four source points aligned along a first direction, each source point having a value, the system comprising: a display; and a processing unit configured to calculate the interpolated value as a first cubic function f 0 (a), wherein: 
 f 0 ( a )= a 0 a 3 +b 0 a 2 +c 0 a+d 0 wherein [ a 0 b 0 c 0 d 0 ] = Q ⁡ [ y - 1 y 0 y 1 y 2 ] , wherein: y −1 is a value of a second-nearest source point in a first direction parallel to a first image axis; y 0 is a value of a nearest source point in the first direction; y 1 is a value of a nearest source point in a second direction opposite the first direction and parallel to the first image axis; y 2 is a value of a second-nearest source point in the second direction; a is the ratio of: the distance between the first interpolation point and the nearest source point in the first direction; to the distance between the nearest source point in the first direction and the nearest source point in the second direction; and Q is equal to [ - 0.3333 1 - 1 0.3333 0.8 - 1.8 1.2 - 0.2 - 0.4667 - 0.2 0.8 - 0.1333 0 1 0 0 ]. the first cubic function being one of three cubic functions forming a piecewise cubic spline, the cubic spline taking the value of each source point at the source point and having a vanishing second derivative at the second-nearest source point in the first direction and at the second-nearest source point in the second direction, the processing unit being further configured to set a pixel value for a color of a pixel of the display to the interpolated value, wherein the four source points are four provisional interpolation points, and the first interpolation point is an ultimate interpolation point, wherein the processing unit is configured to interpolate four times in a third direction, each time using four pixels as source points, to form the four provisional interpolation points, and to interpolate from the four provisional interpolation points, in a fourth direction, perpendicular to the third direction, to form the interpolated value.