Patent ID: 7995247

Claim:
A method of generating a halftone screen code by a computer for embedding information into a type of printed media content comprising at least one pixel, wherein said method comprises the steps of: (a) setting a predetermined threshold value of said halftone screen code; (b) setting a predetermined code length value of said halftone screen code; (c) generating a first group of codes each having said predetermined code length value, wherein each of said codes is represented by a binary bit; (d) calculating a similarity value between each two of said codes, wherein said similarity value is expressed as (n−d)/n, where d is a distance between two of said corresponding said codes, and n is said predetermined code length value; (e) for each two of said codes, comparing said similarity value with said threshold value, wherein when said the similarity value is greater than said threshold value, determining whether said similarity value and said threshold value comparison is completed for all of said codes, wherein when said comparison is not completed for all of said codes, sending said codes with a similarity value smaller than said threshold value as a second group to halftone dots, wherein when said similarity value is less than said threshold value, saving said codes with said similarity value; and (f) exchanging said codes with said halftone dots according to different configurations of said halftone dots to form said halftone screen code.