Patent ID: 7796778

Claim:
A digital watermarking system comprising: a storing unit for storing text information, the text information comprising textual information and one or more background images, the textual information comprising a plurality of textual dot matrixes; a background image obtaining module, for obtaining a background image to be watermarked from the storing unit, wherein the background image comprises a plurality of pixels, and each of the pixels has a brightness value; a pixel determining module for earmarking a pixel to be adjusted, wherein an initial brightness value of the earmarked pixel is in a predetermined range; an encrypting module, for adjusting the brightness value of the earmarked pixel; and a storing module, for storing watermarked text information in the storing unit; wherein the pixel determining module is further configured for earmarking a pixel of the obtained background image, if a length of a bit sequence is not equal to zero and the brightness value of the pixel is in a predetermined range, the bit sequence comprises an instruction for watermarking the text information; the encrypting module is further used for adjusting the brightness value of the earmarked pixel according to a bit value of one bit of the bit sequence; and the storing module is further used for recording the adjusted pixel and corresponding bit value.