MATLAB: What is the function of this code segment in the whole code? Can any one explain

Question

mask = zeros(length(img(:,1)), length(img(1,:)));

>for i=1:1:length(img(:,1))

 >p1=find(img(i,:)~=0,1,'first');
 >p2=find(img(i,:)~=0,1,'last');
   > if(~isempty(p1) && ~isempty(p2))
      >  mask(i,p1:p2) = 1;
    >end

>end

Answer 1

This poorly written code makes a mask where it scans each row and makes the mask "true" from the first non-zero pixel in the row to the last non-zero pixel in the row.