bicubic_filter

deepinv.physics.blur.bicubic_filter(factor=2)

Bicubic filter.

It has size (4*factor, 4*factor) and is defined as

\[\begin{split}\begin{equation*} w(x, y) = \begin{cases} (a + 2)|x|^3 - (a + 3)|x|^2 + 1 & \text{if } |x| \leq 1 \\ a|x|^3 - 5a|x|^2 + 8a|x| - 4a & \text{if } 1 < |x| < 2 \\ 0 & \text{otherwise} \end{cases} \end{equation*}\end{split}\]

for \(x, y \in {-2\text{factor} + 0.5, -2\text{factor} + 0.5 + 1/\text{factor}, \ldots, 2\text{factor} - 0.5}\).

Parameters:

factor (int) – downsampling factor