/dotsecrets

reveal hidden printer dot codes

Primary LanguageMakefile

dotsecrets - reveal hidden printer dot codes

ABOUT

Commercial printers insert a watermark on every printed document, in the form of patterns of dots. dotsecrets reveals these interesting patterns.

EXAMPLE

high resolution scan of a ruler

dot pattern highlighted

$ lp fizzy.pdf
$ (scan printed page to fizzy-scan.jpg)
$ make
matlab -nojvm -nodisplay -nosplash -r "M = extract_printer_dot_mask(imread('1cm-scan.png')); imwrite(M, '1cm-mask.bmp'); exit"
matlab -nojvm -nodisplay -nosplash -r "M = extract_printer_dot_mask(imread('fizzy-scan.jpg'), 240, 5); imwrite(M, 'fizzy-mask.bmp'); exit"
$ open *.bmp
...

MATLAB Central

http://www.mathworks.com/matlabcentral/fileexchange/55284-mcandre-dotsecrets

REQUIREMENTS

  • MATLAB
  • a printer
  • a high quality document camera ("scanner")

BONUS LEVEL

Try dotsecrets with bills.