Method and apparatus to detect watermark that are resistant to resizing, rotation and translation

A processing device operating under the control of a program, the program causing the processing device to carry out a method of detecting a watermark in a two-dimensional frame of data, the frame of data including a plurality of data values representing the watermark embedded in a frame of content data, the method comprising:

• computing a filtered frame of data from the frame of data having at least some harmonic frequency components corresponding to the watermark that are emphasized as compared to at least some frequency components corresponding to the content data;
• computing a two-dimensional Fourier transform of the filtered frame of data to produce a two-dimensional frequency spectrum of the filtered frame of data;
• selecting a set of frequency components associated with the watermark from among the frequency components of the two-dimensional frequency spectrum;
• and
• computing at least one of a rotation value, a resizing value, and a translation value associated with the watermark as compared to a reference watermark using one or more of the frequency components of the selected set.

A storage medium containing a program for causing a processing device to carry out a method of detecting a watermark in a two-dimensional frame of data, the frame of data including a plurality of data values representing the watermark embedded in a frame of content data, the method comprising:

• computing a filtered frame of data from the frame of data having at least some harmonic frequency components corresponding to the watermark that are emphasized as compared to at least some frequency components corresponding to the content data;
• computing a two-dimensional Fourier transform of the filtered frame of data to produce a two-dimensional frequency spectrum of the filtered frame of data;
• selecting a set of frequency components associated with the watermark from among the frequency components of the two-dimensional frequency spectrum;
• and
• computing at least one of a rotation value, a resizing value, and a translation value associated with the watermark as compared to a reference watermark using one or more of the frequency components of the selected set.