function [imout]=removetrend(imagein)



mask=3;

mid=round(mask/2);

range=mask-1;

div=1/(mask*mask);

s = size(imagein);

imout=zeros(s(1),s(2));



for down = 1:s(1)-range;

   for across = 1:s(2)-range;

      tmp = imagein(down:down+range,across:across+range);

      imout(down+mid,across+mid) = div*sum(tmp(:));

   end;

end;





imout=imout-double(imagein);

%t=min(imout(:));

%if t < 0

   %imout=imout-t;

   %imout=imout*255/max(imout(:));

%end;

imout=histeq(uint8(imout));