Embedding data to be embedded as a digital watermark is acquired. Packing
data is formed in which the embedding data is repeatedly connected three times
or more sequentially without interval. Real embedding information is formed such
that a redundancy bit with a fixed length that is used for an error correction
of an information bit is added immediately after the information bit in which the
packing data is subdivided into data each having a fixed length. The real embedding
information is embedded into the image data itself. The embedding mechanism for
the information is not easily understood, and security level is high.
