Simple stretching and compression algorithm using Lagrange's polynomials
Alfredo J. Ramirez · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1990
Most implementations of Fast Fourier Transform (FFT) algorithms available in software packages and libraries require the number of points on the input to be an integral power of two. However most digital images especially those obtained in PC based systems will seldom meet this requirement. This paper will present a simple computational technique to adjust image dimensions to an appropriate size. Nonlinear polynomials are used as the basis for the scheme. The derivation of the basic interpolation functions is presented and a basic three by three mask is obtained. Observations regarding properties of image and mask are made which lead to the reduction of the mask to a three by one. An optimal procedure for utilizing the mask is also presented.