Signal encoding based on spectral requirements

A printed object comprising:

• a white substrate or printed white background comprising a first area;
• an ink mixture printed at a first plurality of spatial locations within the first area, the ink mixture printed such that the first area comprises a second plurality of spatial locations without the ink mixture, the ink mixture comprising white extender and Green 7 ink, the ink mixture comprising a volume or weight ratio of 97.5%-99.75% white extender and 2.5%-0.25% Green 7 ink;
• in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and
• in which i) the white substrate or printed white background, and ii) the ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%.

An image processing method comprising:

• obtaining optically captured imagery representing a printed object, the imagery captured by a scanner have a peak illumination at or around 660 nm, the printed object comprising:
• a substrate or background comprising a first area;
• an ink mixture printed at a first plurality of spatial locations within the first area, the ink mixture printed such that the first area comprises a second plurality of spatial locations without the ink mixture, the ink mixture comprising white extender and ink including a Phthalocyanine green pigment, the ink mixture comprising a volume or weight ratio of 97.5% to 99.75% white extender and 2.5%-0.25% ink;
• in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal carrying a plural-bit payload, and in which i) the substrate or background, and ii) the ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%;
• processing the captured imagery to decode the plural-bit payload from the encoded signal;
• outputting the plural-bit payload.

An image processing method comprising:

• obtaining optically captured imagery representing a printed object, the imagery captured by a scanner have a peak illumination at or around 660 nm, the printed object comprising:
• a white substrate or printed white background comprising a first area, an ink mixture printed at a first plurality of spatial locations within the first area, the ink mixture printed such that the first area comprises a second plurality of spatial locations without the ink mixture, the ink mixture comprising white extender and Green 7 ink, the ink mixture comprising a volume or weight ratio of 97.5%-99.75% white extender and 2.5%-0.25% Green 7 ink, in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and in which i) the white substrate or printed white background, and ii) the ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%;
• processing the captured imagery to decode the plural-bit payload from the encoded signal;
• outputting the plural-bit payload.

A printed object comprising:

• a substrate or background comprising a first area;
• an ink mixture printed at a first plurality of spatial locations within the first area, the ink mixture printed such that the first area comprises a second plurality of spatial locations without the ink mixture, the ink mixture comprising white extender and ink including a Phthalocyanine green pigment, the ink mixture comprising a volume or weight ratio of 97.5%-99.75% white extender and 2.5%-0.25% ink;
• in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and
• in which i) the substrate or background, and ii) the ink mixture comprise a spectral reflectivity difference in a range of 8%-30% at or around 660 nm.