HIDING CODES IN INPUT DATA

The present invention relates to hiding codes in input data, e.g., such as still imagery and motion pictures. One claim recites: embedding an N-bit code with a source signal, N being at least one. The embedding proceeds, for each bit of the N-bit code, according to the following: mapping the bit to a portion of the source signal; changing values of at least two data values associated with the portion in accordance with the bit. The act of changing embeds the N-bit code in a manner that is generally imperceptible to a human observer of the source signal. A related claim recites that the portion includes a data value, and the above method further includes changing the value of the data value in accordance with said bit of the code, an amount of the changing being adjusted based on the value. Of course, other claims and combinations are provided as well.