MATLAB: How do i calculate hessian matrix for an image

hessian

i need to calculate hessian matrix manually.can anyone help?

Best Answer

Hi, you need to compute second derivatives in each direction, using something like:

 [gx, gy] = gradient(double(img));
 [gxx, gxy] = gradient(gx);
 [gxy, gyy] = gradient(gy);

The coefficients of the hessian matrix for each pixel are given by gxx, gxy and gyy.

regards

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MATLAB: Calculating the eigenvalues of a composite matrix

You are overwriting V,D,W every time. The simplest way to avoid this, ignoring the specific size of the variables, is to put the answers into a cell array:

for j=1:n %n=1280
    for i=1:m %m=1024
      HesseM = [Gxx(i,j) Gxy(i,j); Gyx(i,j) Gyy(i,j)];
      [V{j,i},D{j,i},W{j,i}] = eig(HesseM);
    end
end

MATLAB: Error “Too many output arguments” from fmincon

Do you mean I choose 'on' for the option "GradObj'' and 'GradConstr' and need to switch them to 'off'?

Either switch them off or provide the gradients, e.g.,

function [obj,grad] = e1_funcOptimal(x)
     obj = -x(1,10);
     
     if nargout>1
       grad=zeros(size(x)); 
        grad(1,10)=-1;
     end
 
end

Best Answer

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