Information Embedding Method forHome Printing ofCertifications

Inthispaper, we describe ourdot-pattern code, whichcanembedinformation ontothepaper. Itsmainfeatures are1)noneedtoreserve aspecial roomforthecode, 2)obscure andunnoticeable, 3)comparatively large information capacity, 4)theabsolute coordinates inthepaperismeasurable. We describe howtoembedanddetect theinformation onto/from thepaper,andwe estimate itby examination. From the examination, wefoundthatourdot-pattern codeisapplicable to various kinds ofpapers, printers including ink-jet andscanners. We alsofoundthatevenwhenthedensity oftheblackdotis greater than6%,over8,000 bits couldbesafely embeddedwith errorratelessthan10-6. We alsofoundthattheembedded information couldbedetected correctly after thepaperhadbeen damaged.