Fast interpolation by FFT with greatly increased accuracy
M.D. Macleod · Electronics Letters · 1993
When the FFT (or DCT or DST) is used for fast interpolation, errors arise due to the assumed periodicity in the data, and the resulting implied discontinuities of the function and its derivatives at the block edges. By adding simple functions before interpolation and subtracting them again afterwards, these interpolation errors can be removed.