For an newer article on this topic, please read Interpolation Revisited
AT 200% interpolation, not much difference could be seen between the various interpolation methods. However, as images are enlarged to greater sizes, the interpolations become more critical. In this article, the images are interpolated at 300% and examined.
Figures 1 to 5 show the Egret at 300%.
Figures 6 to 10 show the Mojave Green at 300%.
Figures 11 to 15 show the clock at 300%.
Figures 16 to 20 show the doll at 300%.
Two conclusions can be drawn from the 300% interpolations:
At 300% interpolation, the best interpolation method for an image may depend on the image itself. With these four images, the clock showed virtually no difference between four of the interpolation methods, the Mojave Green showed only minimal differences, the egret showed sharper and cleaner images with the Genuine Fractals and S-Spline interpolations, and the doll showed a far superior interpolation from Genuine Fractals.
The best interpolation method may depend on the size of the interpolation. At 200% interpolation, the differences between the interpolation methods were relatively small and probably would not be noticeable in a print. At 300% interpolation, differences between the interpolations methods start to become evident.