Patent ID: 8050450

Claim:
A method of watermarking a digital image to embed a plural-bit watermark specified by a payload tile, said image comprising an two-dimensional array of elements spanning a first area, said payload tile comprising plural values spanning a two-dimensional second area smaller than the first area, said method comprising the acts: defining a first contiguous region and a second contiguous region, the first region corresponding to a portion of said image where a characteristic of said image falls within a first range, the second region corresponding to a portion of said image where said characteristic of said image falls within a second range different than the first range, the first region having a first control value associated therewith, and the second region having a second control value associated therewith that is different than the first control value, the first and second regions having different sizes; changing the value of the image elements in the first region in accordance with the payload tile values and the first control value, and changing the value of the image elements in the second region in accordance with said payload tile values and the second control value; wherein the same payload tile values encode the same plural-bit watermark in both the first and second regions, but change the image by differing amounts in said regions depending on the control values for said regions.