I need to find the orientation of a fingerprint.I have a code that uses gaussian filter that I got from mathworks.in but I'm getting a weird error that I cant figure out what to do about.

function [orientim, reliability] = ...
         ridgeorient(im, gradientsigma, blocksigma, orientsmoothsigma)

    [rows,cols] = size(im);

    % Calculate image gradients.
    sze = fix(6*gradientsigma);   if ~mod(sze,2); sze = sze+1; end
    f = fspecial('gaussian', sze, gradientsigma); % Generate Gaussian filter.
    [x,y] = gradient(f);                        % Gradient of Gausian.
    [fx,fy]=meshgrid(x,y);
   Gx = filter1(fx, im); % Gradient of the image in x
    Gy = filter1(fy, im); % ... and y
    %Gx=imfilter(im,fx,'conv','replicate');
     %Gy=imfilter(im,fy,'conv','replicate');

    % Estimate the local ridge orientation at each point by finding the
    % principal axis of variation in the image gradients.

    Gxx = Gx.^2;       % Covariance data for the image gradients
    Gxy = Gx.*Gy;
    Gyy = Gy.^2;

    % Now smooth the covariance data to perform a weighted summation of the
    % data.
    sze = fix(6*blocksigma);   if ~mod(sze,2); sze = sze+1; end    
    f = fspecial('gaussian', sze, blocksigma);
    Gxx = filter2(f, Gxx); 
    Gxy = 2*filter2(f, Gxy);
    Gyy = filter2(f, Gyy);

    % Analytic solution of principal direction
    denom = sqrt(Gxy.^2 + (Gxx - Gyy).^2) + eps;
    sin2theta = Gxy./denom;            % Sine and cosine of doubled angles
    cos2theta = (Gxx-Gyy)./denom;

    sze = fix(6*orientsmoothsigma);   if ~mod(sze,2); sze = sze+1; end    
    f = fspecial('gaussian', sze, orientsmoothsigma);    
    cos2theta = filter2(f, cos2theta); % Smoothed sine and cosine of
    sin2theta = filter2(f, sin2theta); % doubled angles

    orientim = pi/2 + atan2(sin2theta,cos2theta)/2;

??? Undefined function or method 'conv2' for input arguments of type 'double' and attributes 'full 3d real'.

Error in ==> filter2 at 73 y = conv2(hcol, hrow, x, shape);

Error in ==> ridgeorient at 56 Gxx = filter2(f, Gxx);

Answer 1

[Walter Roberson]

Is your image possibly an RGB (truecolor) image? That code is not designed to support that. Try using rgb2gray() on your original image and passing that grayscale image to this routine.