I'm not an specialist, but you can start with <a href="https://en.wikipedia.org/wiki/Spatial_anti-aliasing" rel="nofollow">https://en.wikipedia.org/wiki/Spatial_anti-aliasing</a>
you can read <a href="https://en.wikipedia.org/wiki/B-spline" rel="nofollow">https://en.wikipedia.org/wiki/B-spline</a><p>most of them simply use a lasso method.