Digital watermarking in data representing color channels

An apparatus comprising:

• a processor configured to:
• receive optically captured data associated with printed media, wherein the received captured data represents a blue channel, a green channel and a red channel, and wherein a first digital watermarking is embedded in the printed media;
• scale the blue channel with a first factor;
• scale a sum of the red channel and the green channel with a second factor;
• subtract the scaled sum of the red channel and the green channel from the scaled blue channel and adding a shift factor to yield a detection signal;
• and
• search for the first digital watermarking in the detection signal.

A non-transitory tangible computer-readable medium having instructions stored thereon, the instructions comprising:

• instructions to receive optically captured data associated with printed media, wherein the received captured data represents a blue channel, a green channel and a red channel, and wherein a first digital watermarking is embedded in the printed media;
• instructions to scale the blue channel with a first factor;
• instructions to scale a sum of the red channel and the green channel with a second factor;
• instructions to subtract the scaled sum of the red channel and the green channel from the scaled blue channel and adding a shift factor to yield a detection signal;
• and
• instructions to search for the first digital watermarking in the detection signal.