How is this code binarizing an image?

Is there anyone way someone would be able to explain to me what these for loops are doing to turn that image into binary?

%binarization
% im1 being the orignal image that is passed to this function
Radius=30;        
intA=10;        
lengthV=length(img1(:,1));  % vertical length 
lengthH=length(img1(1,:));  horizontal length

for offV=1:lengthV/Radius          % Vertical Offset
    for offH=1:lengthH/Radius      % Horizontal offset    
        % Convert region of radius Radius in a row
        for i=1:Radius
            for j=1:Radius
                Obl((i-1)*Radius+j)=img1(j+(offV*Radius-Radius),i+(offH*Radius-Radius));
            end
        end
        Obl;

          Thres=mean(Obl)+intA;        % Threshold

          for i=1:Radius
              for j=1:Radius
                  if img1(j+(offV*Radius-Radius),i+(offH*Radius-Radius)) > Thres
                      bw(j+(offV*Radius-Radius),i+(offH*Radius-Radius))=0;
                  else bw(j+(offV*Radius-Radius),i+(offH*Radius-Radius))=1;
                  end
              end
          end
      end
  end
  bw;

Answer 1

[Guillaume]

The code divides the image into 30x30 square block (size is given by the badly named Radius). It calculates the mean intensity of each block, adds 10 (value given by intA) and uses that as a threshold. Anything in the block above the threshold is converted to black, everything else to white.

The whole code is badly written, obviously by someone who's not very good at matlab: convoluted way of calculating the size of the image, slow and unnecessary loops, badly named variables, lack of preallocation, useless if, and more

You can replace the entirety of the code with just one line:

bw = blockproc(img1, [30 30],(@b) b.data <= mean(b.data(:)) + 10);

[Recap]

Thank you for your answer. In the one line of code you gave. what is b and where are you getting it from?

[Walter Roberson]

"b" is the dummy parameter for the anonymous function

(@b) b.data <= mean(b.data(:)) + 10

That is, b is whatever value that blockproc passed in to the anonymous function. See blockproc for information about the struct that it passes to anonymous functions.

[Recap]

Correction to the above "one line" code

bw = blockproc(img1, [30 30],@(b) b.data <= mean(b.data(:)) + 10);