document image binarization [closed]

Answer 1

How about starting with simply adapting the threshold based on the local neighborhood?

im = rgb2gray(im);
im = im2double(im);
f_makebw = @(I) im2bw(I.data, double(median(I.data(:)))/1.45);
bw = ~blockproc(im, [128 128], f_makebw);

Result: