Shifted linear interpolation for images

ABSTRACT: In this work we study the shifted linear interpolation (SLI) method and apply this method in wavelet domain in addition to the spatial domain. The SLI is computationally cheaper than the cubic interpolation and a little more computationally complicated than the standard linear in this way: the computed optimal shift for the SLI is used to change coefficients amplitude and location of the standard linear interpolation. In the spatial domain we achieve a noticeable improvement over the standard linear interpolation in cost of some simple computations. We compare the SLI with other interpolation methods in practical test to ensure its superiority over others. We then evaluate the SLI in wavelet domain, so we carry out our experimental tests in this domain. The SLI method is originated from the principle attempt to minimizing the least square error which is much in the case of the standard linear interpolation. We Evaluate the SLI with experimental results such as rotation and magnification in spatial and wavelet domain. In rotation experiment, we use the SNR and SSIM to evaluate the standard linear, the SLI, and the cubic methods and this comparison is carried out in spatial domain. A second practical experiment is magnification which is done in spatial as well as wavelet domain and the comparison between the nearest, the standard linear, the SLI and the cubic is hold by visual and objective evaluation. Keywords: Linear interpolation, Shifted linear interpolation, Super resolution, Spline functions, Discrete wavelet transform. …………………………………………………………………………………………………………………………