How to perform 2D fit of image using Fit2D Gaussian optimization toolbox

Hello, I am trying to perform a 2D fit using this toolbox: https://www.mathworks.com/matlabcentral/fileexchange/41938-fit-2d-gaussian-with-optimization-toolbox?status=SUCCESS

I am having trouble converting the image into the required format for this toolbox.

The toolbox instructions are as follows:

FMGAUSSFIT performs a gaussian fit on 3D data (x,y,z). [fitresult,..., rr] = fmgaussfit(xx,yy,zz) uses ZZ for the surface height. XX and YY are vectors or matrices defining the x and y components of a surface. If XX and YY are vectors, length(XX) = n and length(YY) = m, where [m,n] = size(Z). In this case, the vertices of the surface faces are (XX(j), YY(i), ZZ(i,j)) triples. To create XX and YY matrices for arbitrary domains, use the meshgrid function. FMGAUSSFIT uses the lsqcurvefit tool, and the OPTIMZATION TOOLBOX. The initial guess for the gaussian is places at the maxima in the ZZ plane. The fit is restricted to be in the span of XX and YY.

clc

clear all

close all

cmap = jet(256);

new_cmap_range = linspace(120, 300, 256);

new_cmap = interp1(linspace(0, 1, 256), cmap, linspace(0, 1, 256), 'linear');

filename = 'ANP_polarizer50_90mm.png';

I0 = imread(filename);

%----------------------------------

%extract x,y,z coordinates

[xx, yy] = meshgrid(1:size(I0, 2), 1:size(I0, 1));

zz = double(I0);

%use 2D Gauss fit

[fitresult, zfit, fiterr, zerr, resnorm, rr] = fmgaussfit(xx,yy,zz);

imshow(I0,new_cmap);

axis on

set(gca, 'YDir', 'normal'); %set y axis direction

title('Beam');

colorbar; %add colorbar

impixelinfo;

xlabel('Position (px)');

ylabel('Postion (px)');

[Mathieu NOE]

can you share the image file as well ?