Cubic convolution is a method used to determine the gray levels in an image. This is determined by the weighted average of the 16 closest pixels to the input coordinates. Then that value is assigned to the output coordinates. This method is slightly better than bilinear interpolation, and it does not have the disjointed appearance of nearest neighbor interpolation. Cubic convolution requires about 10 times the computation time required by the nearest neighbor method.
Cubic Convolution: This resampling method assigns the average DN of the sixteen pixels closest to the input pixel (in a 4x4 window) to the corresponding output pixel. The mathematical function is cubic.
