Method and apparatus for embedding information in an image

An apparatus for embedding information in an image printed on a print medium, comprising:

• an ink jet print head for printing said image during relative movement between said print medium and said ink jet print head along a horizontal axis;
• a processor;
• and
• a memory, said memory storing software executable by said processor, said software including instructions for:
• printing a plurality of first lines along a vertical axis, each of said first lines including a plurality of first dots and a plurality of second dots, said second dots being offset from said first dots along said horizontal axis by a first amount;
• and
• printing a plurality of second lines along said vertical axis, each of said second lines including a plurality of third dots and a plurality of fourth dots, said fourth dots being offset from said third dots along said horizontal axis by a second amount different than said first amount;
• wherein said first lines represent a first value in an encoding scheme and said second lines represent a second value in said encoding scheme, and wherein said information is encoded in said image using said encoding scheme.