filt_tanb142013-07-01 13:12:59localhostconverted to 1.6 markup132010-07-02 18:35:51139.52.19.64122010-07-02 18:24:10139.52.19.64112007-08-13 16:28:35penczek102007-06-21 20:25:28bmb24.med.uth.tmc.edu92007-06-20 21:31:07bmb24.med.uth.tmc.edu82007-06-20 20:55:55bmb24.med.uth.tmc.edu72006-07-23 19:50:52penczek62006-07-23 19:48:17penczek52006-07-23 19:47:45penczek42006-07-23 19:44:58penczek32006-07-23 19:44:19penczek22006-07-23 19:42:37penczek12006-07-23 19:38:37penczekNamefilt_tanb - hyperbolic tangent band-pass Fourier filter Usageoutput = filt_tanb(image, freql, low_fall_off, freqh, high_fall_off, pad) Inputimageinput image (can be either real or Fourier) freqllow-end frequency of the filter pass-band low_fall_offfall off of the filter at the low-end frequency freqhhigh-end frequency of the filter pass-band high_fall_offfall off of the filter at the high-and frequency padlogical 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). All frequencies are in absolute frequency units ``f_a``

and their valid range is [0:0.5]. Outputoutputfiltered image. Output image is real when input image is real or Fourier when input image is Fourier MethodFourier transform of the input image is multiplied by a radially symmetric hyperbolic tangent filter: ``H(f) = 0.5{tanh[(pi(f+f_H))/(2a_H(f_H-f_L)))]-tanh[(pi(f-f_H))/(2a_H(f_H-f_L))]-tanh[(pi(f+f_L))/(2a_L(f_H-f_L)))]+tanh[(pi(f-f_L))/(2a_L(f_H-f_L))]}``

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). ReferenceBasokur, A. T., 1998. Digital filter design using the hyperbolic tangent functions. Journal of the Balkan Geophysical Society 1, 14-18. Author / MaintainerPawel A. Penczek Keywordscategory 1FILTER category 2FOURIER Maturitystableworks for most people, has been tested; test cases/examples available.