Why bicubic interpolation uses a 4x4 pixels neighborhood?

edit

Hello, I am just starting to learn about image interpolation. I already read some papers about it and I'm doing some tests applying the bicubic interpolation (INTER_CUBIC) using the resize function provided by the OpenCV library.

In 2 papers that I read, the authors wrote that the bicubic interpolation uses a neighborhood of 16x16 pixels, but in the OpenCV documentation, it says that the bicubic interpolation method uses a neighborhood of 4x4 pixels.

Doc: http://docs.opencv.org/2.4/modules/imgproc/doc/geometric_transformations.html

Can someone explain to me why it uses a 4x4 neighborhood? What is the main difference between using a 16x16 neighborhood and a 4x4 neighborhood?

Thanks in advance

Note: keep in mind that I'm a newbie.