The edge-based method standardized in ISO 12233 approximates the modulation transfer function (MTF) as a function of horizontal or vertical spatial frequency by analyzing a supersampled edge profile obtained from the captured image of a slightly slanted bi-tonal edge. The method describes the slanted projection of pixels sampled in a square array into a linear array of subpixel-wide bins. An ad hoc correction is available to accommodate the diagonal MTF measurements. However, using a fixed oversampling ratio in the standard method degrades the accuracy and precision of the MTF estimates, owing to the periodic misalignment between the projection paths and the bin array. A new edge-based method using a variable oversampling ratio, OMNI-sine, has been proposed to remedy this misalignment. In this study, computer simulations were performed to demonstrate the accuracy and precision of the MTF estimates over a full range of finely sampled slant angles.