k-Wave Toolbox

getAlphaFilter

Create filter for medium.alpha_filter

Syntax

alpha_filter = getAlphaFilter(kgrid, medium, filter_cutoff)
alpha_filter = getAlphaFilter(kgrid, medium, filter_cutoff, taper_ratio)

Description

getAlphaFilter uses getWin to create a Tukey window via rotation to pass to the medium.alpha_filter input field of the first order simulation functions (kspaceFirstOrder1D, kspaceFirstOrder2D, and kspaceFirstOrder3D). This parameter is used to regularise time reversal image reconstruction when absorption compensation is included.

Inputs

kgrid

k-Wave grid structure returned by makeGrid

medium

k-Wave medium structure

filter_cutoff

alpha_filter cutoff frequency [Hz], where

filter_cutoff = [f_all] in 1-D
filter_cutoff = [f_all] or [f_x, f_y] in 2-D
filter_cutoff = [f_all] or [f_x, f_y, f_z] in 3-D

Any of the filter_cutoff inputs may be set to 'max' to set the cutoff frequency to the maximum frequency supported by the grid

Optional Inputs

taper_ratio

taper ratio for Tukey Window (default = 0.5)

Outputs

alpha_filter

filter

Examples

Image Reconstruction With Compensation For Acoustic Absorption