www.pudn.com > Normal_encoding.rar > gaborconvolve.m
% gaborconvolve - function for convolving each row of an image with 1D log-Gabor filters
%
% Usage:
% [template, mask] = createiristemplate(eyeimage_filename)
%
% Arguments:
% im - the image to convolve
% nscale - number of filters to use
% minWaveLength - wavelength of the basis filter
% mult - multiplicative factor between each filter
% sigmaOnf - 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.
%
% Output:
% E0 - a 1D cell array of complex valued comvolution results
%
% Author:
% Original 'gaborconvolve' by Peter Kovesi, 2001
% Heavily modified by Libor Masek, 2003
% masekl01@csse.uwa.edu.au
% School of Computer Science & Software Engineering
% The University of Western Australia
% November 2003
function [EO, filtersum] = gaborconvolve(im, nscale, minWaveLength, mult, ...
sigmaOnf)
[rows cols] = size(im);
filtersum = zeros(1,size(im,2));
EO = cell(1, nscale); % Pre-allocate cell array
ndata = cols;
if mod(ndata,2) == 1 % If there is an odd No of data points
ndata = ndata-1; % throw away the last one.
end
logGabor = zeros(1,ndata);
result = zeros(rows,ndata);
radius = [0:fix(ndata/2)]/fix(ndata/2)/2; % Frequency values 0 - 0.5
radius(1) = 1;
wavelength = minWaveLength; % Initialize filter wavelength.
for s = 1:nscale, % For each scale.
% Construct the filter - first calculate the radial filter component.
fo = 1.0/wavelength; % Centre frequency of filter.
rfo = fo/0.5; % Normalised radius from centre of frequency plane
% corresponding to fo.
logGabor(1:ndata/2+1) = exp((-(log(radius/fo)).^2) / (2 * log(sigmaOnf)^2));
logGabor(1) = 0;
filter = logGabor;
filtersum = filtersum+filter;
% for each row of the input image, do the convolution, back transform
for r = 1:rows % For each row
signal = im(r,1:ndata);
imagefft = fft( signal );
result(r,:) = ifft(imagefft .* filter);
end
% save the ouput for each scale
EO{s} = result;
wavelength = wavelength * mult; % Finally calculate Wavelength of next filter
end % ... and process the next scale
filtersum = fftshift(filtersum);