Image Processing, Photography, Photoshop, Computer Vision, Software.
Lagrange polynomials, cubic splines or cubic convolution algorithms. When we interpolate, we are estimating unknown data from known data. If we shot an image with a DSLR at 16 MP, then your known data is that you have 4928 x 3264 pixels (or 3264 x 4928 pixels), depending on the orientation