Template:Interpolators

Nearest neighbor: to be used for testing purposes only because of the large amount of artifacts it produces. As a tradeoff it’s the fastest of all.
Bilinear: represents a decent quality/speed ratio.
Bicubic: if you don’t know which one to pick this is the one you should be using. Any differences from Bilinear will be hardly visible to the naked eye, but can be seen on highly contrasted lines. It is the default recommended setting.
Bicubic Sharper: same formula as Bicubic with some strength added (same as bicubic, only a touch stronger). This sampling mode is the same as the one found in the "Image Size" dialog, in the "Resample Image" drop-down of Adobe Photoshop.
Bicubic smoother: same formula as Bicubic with less strength (same as bicubic only a touch lighter). This sampling mode is the same as the one found in the "Image Size" dialog, in the "Resample Image" drop-down of Adobe Photoshop.
Spline36: the use of this powerful interpolator is to be reserved for cases where heavy post-processing will take place. To the naked eye, there is absolutely no visible difference with Bicubic.
Spline64: more powerful, slower but generally even better than Spline36 (if you can “see” the difference!). Same as for the Spline36 interpolator: to be reserved for cases where heavy post-processing, including reprojection and successive image transformations will take place.