gaborfilter0.m

基于瑞利波及lamb波的频散曲线程序,可用于根据实验绘制Rali波及lamb波的频散曲线,检验其在不同材料中的频散特性

%%%%%%%VERSION 2 
%%ANOTHER DESCRIBTION OF GABOR FILTER 

%The Gabor filter is basically a Gaussian (with variances sx and sy along x  
%  and y-axes respectively) 
%modulated by a complex sinusoid (with centre frequencies U and V along  
% x and y-axes respectively) 
%described by the following equation 
%% 
%                            -1     x' ^     y'  ^ 
%%% G(x,y,theta,f) =  exp ([----{(----) 2+(----) 2}])*cos(2*pi*f*x'); 
%                             2    sx'       sy' 
%%% x' = x*cos(theta)+y*sin(theta); 
%%% y' = y*cos(theta)-x*sin(theta); 

%% Describtion : 

%% I : Input image 
%% Sx & Sy : Variances along x and y-axes respectively 
%% Sx & Sy : Variances along x and y-axes respectively 
%% f : The frequency of the sinusoidal function 
%% theta : The orientation of Gabor filter 

%% G : The output filter as described above 
%% gabout : The output filtered image 



%%  Author : Ahmad poursaberi  e-mail : [e-mail] 
%%          Faulty of Engineering, Electrical&Computer Department,Tehran 
%%          University,Iran,June 2004 

function [G,gabout] = gaborfilter0(I,Sx,Sy,f,theta); 
% 如果I不是double类型,将矩阵I转化为double类型 
if isa(I,'double')~=1 
    I = double(I); 
end 

for x = -fix(Sx):fix(Sx) 
    for y = -fix(Sy):fix(Sy) 
        xPrime = x * cos(theta) + y * sin(theta); 
        yPrime = y * cos(theta) - x * sin(theta); 
for x = -fix(Sx):fix(Sx) 
        G(fix(Sx)+x+1,fix(Sy)+y+1) = exp(-.5*((xPrime/Sx)^2+... 
                                    (yPrime/Sy)^2))*cos(2*pi*f*xPrime); 
    end 
end 

Regabout = conv2(I,double(real(G)),'same'); 
Imgabout = conv2(I,double(imag(G)),'same'); 
gabout = sqrt(Imgabout.*Imgabout + Regabout.*Regabout);