%?GABORCONVOLVE?-?function?for?convolving?image?with?log-Gabor?filters
%
%?Usage:?EO?=?gaborconvolve（im??nscale?norient?minWaveLength?mult?...
%			????sigmaOnf?dThetaOnSigma?feedback）
%
%?Arguments:
%?The?convolutions?are?done?via?the?FFT.??Many?of?the?parameters?relate?
%?to?the?specification?of?the?filters?in?the?frequency?plane.??
%
%???Variable???????Suggested???Description
%???name???????????value
%??----------------------------------------------------------
%????im????????????????????????Image?to?be?convolved.
%????nscale??????????=?4;??????Number?of?wavelet?scales.
%????norient?????????=?6;??????Number?of?filter?orientations.
%????minWaveLength???=?3;??????Wavelength?of?smallest?scale?filter.
%????mult????????????=?2;??????Scaling?factor?between?successive?filters.
%????sigmaOnf????????=?0.65;???Ratio?of?the?standard?deviation?of?the
%??????????????????????????????Gaussian?describing?the?log?Gabor?filter‘s
%??????????????????????????????transfer?function?in?the?frequency?domain
%??????????????????????????????to?the?filter?center?frequency.?
%????dThetaOnSigma???=?1.5;????Ratio?of?angular?interval?between?filter
%??????????????????????????????orientations?and?the?standard?deviation?of
%??????????????????????????????the?angular?Gaussian?function?used?to
%??????????????????????????????construct?filters?in?the?freq.?plane.
%????feedback?????????0/1??????Optional?parameter.??If?set?to?1?a?message
%??????????????????????????????indicating?which?orientation?is?being
%??????????????????????????????processed?is?printed?on?the?screen.
%
%?Returns:
%
%???EO?a?2D?cell?array?of?complex?valued?convolution?results
%
%????????EO{so}?=?convolution?result?for?scale?s?and?orientation?o.
%????????The?real?part?is?the?result?of?convolving?with?the?even
%????????symmetric?filter?the?imaginary?part?is?the?result?from
%????????convolution?with?the?odd?symmetric?filter.
%
%????????Hence:
%????????abs（EO{so}）?returns?the?magnitude?of?the?convolution?over?the
%?????????????????????image?at?scale?s?and?orientation?o.
%????????angle（EO{so}）?returns?the?phase?angles.
%???
%
%?Notes?on?filter?settings?to?obtain?even?coverage?of?the?spectrum
%?dthetaOnSigma?1.5
%?sigmaOnf??.85???mult?1.3
%?sigmaOnf??.75???mult?1.6?????（bandwidth?~1?octave）
%?sigmaOnf??.65???mult?2.1
%?sigmaOnf??.55???mult?3???????（bandwidth?~2?octaves）
%???????????????????????????????????????????????????????
%?For?maximum?speed?the?input?image?should?be?square?and?have?a?
%?size?that?is?a?power?of?2?but?the?code?will?operate?on?images
%?of?arbitrary?size.??
%
%
%?The?determination?of?mult?given?sigmaOnf?is?entirely?empirical
%?What?I?do?is?plot?out?the?sum?of?the?filters?in?the?frequency?domain
%?and?see?how?even?the?coverage?of?the?spectrum?is.
%?If?there?are?concentric?‘gaps‘?in?the?spectrum?one?needs?to
%?reduce?mult?and/or?reduce?sigmaOnf?（which?increases?filter?bandwidth）
%
%?If?there?are?‘gaps‘?radiating?outwards?then?one?needs?to?reduce
%?dthetaOnSigma?（increasing?angular?bandwidth?of?

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????7461??2006-09-22?11:23??gaborfilters.m

-----------?---------??----------?-----??----

?????????????????7679????????????????????2