Otsu Threshold algorithm function for blockproc

Hello! I try to write an Otsu Threshold algorithm function to be used later along with the blockproc. Here is my code:

clc; clear; close all;

function out = graythresh(im)
if isstruct(im)
    im = im.data;
end

if ~isempty(im)
   I = im2uint8(im(:));
   num_bins = 256;
   counts = imhist(I,num_bins);
   P = counts/sum(counts);
   omega = cumsum(p);
   mu = cusum(p.*(1:num_bins)');
   mu_t = mu(end);

previous_state = warning('off','MATLAB:divideBYZero');
sigma_b_squared = (mu_t*omega-mu).^2./(omega.*(1-omega));
warning(previous_state);

maxval = max(sigma_b_squared);
isfinite_maxval = isfinite(maxval);
if isfinite_maxval
    idx = mean(find(sigma_b_squared == maxval));
    level = (idx-1)/(num_bins-1);
    else
    level = 0.0;
end
if nargout > 1
    if isfinite_maxval
     em = maxval/sum(p.*((1:num_bins).^2)')-mu_t^2);
    else
        em = 0;
    end
end

out = (im>level*max(im(:)));
disp(['Threshold =',num2str(round(255*level))])

However, this code cannot be run successfully. The command window state that

Error: File: OTSUBLOCK.m Line: 3 Column: 1
Function definitions are not permitted in this context.

Please kindly give me advices

Thankyou!

Answer 1

[Walter Roberson]

You must delete the first line, the one that says

clc; clear; close all;

Also, you must either rename the file from OTSUBLOCK.m to graythresh.m or else you must change the "function out = graythresh(im)" to

function out = OUTSUBLOCK(im)

[Issara Laosuwan]

Thank you very much!