You are not allowed to use this action.

Clear message

Name

filt_tanb - hyperbolic tangent band-pass Fourier filter

Usage

output = filt_tanb(image, freql, low_fall_off, freqh, high_fall_off, pad)

Input

image
input image (can be either real or Fourier)
freql
low-end frequency of the filter pass-band
low_fall_off
fall off of the filter at the low-end frequency
freqh
high-end frequency of the filter pass-band
high_fall_off
fall off of the filter at the high-and frequency
pad
logical flag specifying whether before filtering the image should be padded with zeroes in real space to twice the size (this helps avoiding aliasing artifacts). (Default pad = False).

Output

output
filtered image. Output image is real when input image is real or Fourier when input image is Fourier

Method

Fourier transform of the input image is multiplied by a radially symmetric hyperbolic tangent filter:

where `f_L` if the low-end frequency of the filter pass-band (freql), `f_H` if the high-end frequency of the filter pass-band (freqh), `a_L` is the fall off of the filter at the low-end frequency (low_fall_off), and `a_H` is the fall off of the filter at the high-end frequency (high_fall_off).

Reference

Basokur, A. T., 1998. Digital filter design using the hyperbolic tangent functions. Journal of the Balkan Geophysical Society 1, 14-18.

Author / Maintainer

Pawel A. Penczek

Keywords

category 1
FILTER
category 2
FOURIER

Files

filter.py

Maturity

stable
works for most people, has been tested; test cases/examples available.

Bugs

None. It is perfect.