Methods and apparatus for enhancing the robustness of watermark extraction
from digital host content are provided. Embedded watermarks may be
extracted from received digital host content in accordance with a stego
key. A first watermark is extracted and a number of errors in the first
extracted watermark is assessed. If the number of errors is above a first
pre-determined value, at least a second watermark is extracted from the
host content. A number of errors in at least the second extracted
watermark is assessed. If the number of errors in at least the second
extracted watermark is above a second pre-determined value, the
extraction results for the extracted watermarks are combined in order to
cumulatively assess the validity of the first extracted watermark and at
least the second extracted watermark.