Fast bicubic interpolation algorithm?

[blue_tomato]

I am sorry if this is slightly off topic, but it is related to a LWJGL game project I am doing...

I have eight points forming the corners of a cube.

Each point is associated with a color, and I need to find the interpolated color of any point within this cube.

I tried a simple bilinear filtering approach, but that gives too "square" results. A bicubic filtering approach would be perfect though, and there might be other good algorithms out there as well..?

Do you know of a fast algorithm to solve this?

Thanks