i am doing sclera based authentication project in that i need to perform sclera vessel pattern enhancement using gabor filter ,plese help me to modify the below code and to set parameters of gabor filter

i am doing project on sclera based authentication,i have done sclera area detection now i want to do sclera veins enhancement ,i tried that using gabor filter i have attached the code of gabor filter ,but it enhances edges of an eye rather than sclera vains ,what changes i should do so that only sclera veins will be enhanced .

desired outut is attached as "blood vessel enhanced umage".

code for gabor filter :

theta=pi/2;
lambda =3.5;
gamma=0.3;
sigma=2.8;
psi=0;

sigma_x = sigma;
sigma_y = sigma/gamma;

nstds = 5;
xmax = max(abs(nstds*sigma_x*cos(theta)),abs(nstds*sigma_y*sin(theta)));
xmax = ceil(max(1,xmax));
ymax = max(abs(nstds*sigma_x*sin(theta)),abs(nstds*sigma_y*cos(theta)));
ymax = ceil(max(1,ymax));
xmin = -xmax; ymin = -ymax;
[x,y] = meshgrid(xmin:xmax,ymin:ymax);

x_theta=x*cos(theta)+y*sin(theta);
y_theta=-x*sin(theta)+y*cos(theta);

gb= exp(-.5*(x_theta.^2/sigma_x^2+y_theta.^2/sigma_y^2)).*cos(2*pi/lambda*x_theta+psi);

%subplot(3,2,5);
%imshow(gb);
%title('theta=...');
%imagesc(gb);
%colormap(gray);
%title('theta=...');

image_double=im2double(K);
figure,subplot(2,2,1);
%imshow(image_double);
%figure(3);
filtered1 = conv2(image_double,gb);
%subplot(3,2,5);
imshow(filtered1);
title('gabor filter when theta is pi/2');
%colormap(gray);
%title('theta=pi/2');