# What is an 'Oriented' Band-pass Filter?

In this research paper, Section 4.1 talks about a filter called "Oriented Band-pass Filter".

What does it actually mean by 'Orientation'?

Also, the article gives a function,

$$H(u, v) = \frac{1}{1 + 0.414(\sqrt{\frac{u^*}{D_h} + \frac{v^*}{D_v} })^{2n}}$$

Can you please explain this function in layman's terms?

What are $u$, $v$?

$u,v$ are the horizontal and vertical frequencies while $u^*,v^*$ are the rotated frequencies. If i understand correctly, they are looking for a line in an image with unknown rotation (aka slope) so they create of filter-bank of oriented filter, each with a different rotation.