Signal Encoding for Physical Objects including Dark Ink

Abstract

This disclosure relates to advanced image signal processing technology including encoded signals and digital watermarking. One implementation is directed a printed object comprising: a substrate comprising a first area; a first colored ink or design printed within the first area, the first colored ink or design comprising a spectral reflectivity of less than or equal to 20% at or around 660 nm; a colored ink mixture printed over the first colored ink or design at a first plurality of spatial locations within the first area, the colored ink mixture printed such that the first area comprises a second plurality of spatial locations without the colored ink mixture, the colored ink mixture comprising opaque white ink and a first colorant, wherein the color ink mixture comprises a spectral reflectivity greater than the first colored ink or design at or around 660 nm, and wherein colored ink mixture comprises a spectral reflectivity less than the first colored ink or design in the range of 495 nm-570 nm; in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and in which the first colored ink or design and the colored ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%. Of course, other objects, methods, packages, labels, containers, systems and apparatus are described in this patent document.

What is claimed is: 
     
         1 . A printed object comprising:
 a substrate comprising a first area;   a first colored ink or design printed within the first area, the first colored ink or design comprising a spectral reflectivity of less than or equal to 20% at or around 660 nm;   a colored ink mixture printed over the first colored ink or design at a first plurality of spatial locations within the first area, the colored ink mixture printed such that the first area comprises a second plurality of spatial locations without the colored ink mixture, the colored ink mixture comprising opaque white ink and a first colorant, wherein the colored ink mixture comprises a spectral reflectivity greater than the first colored ink or design at or around 660 nm, and wherein colored ink mixture comprises a spectral reflectivity less than the first colored ink or design in the range of 495 nm-570 nm;   in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and   in which the first colored ink or design and the colored ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%.   
     
     
         2 . The printed object of  claim 1  in which the colored ink mixture comprises opaque white ink and a plurality of colorants including the first colorant. 
     
     
         3 . The printed object of  claim 2 , in which the plurality of colorants comprises Lithol Rubine, and the first colorant comprises Carbazole Violet. 
     
     
         4 . The printed object of  claim 3  in which the colored ink mixture comprises by weight or volume 30%-42% Lithol Rubine, 8%-22% Carbazole Violet and 44%-56% Opaque White. 
     
     
         5 . The printed object of  claim 4  in which the colored ink mixture comprises by weight or volume 36% Lithol Rubine, 14% Carbazole Violet and 50% Opaque White. 
     
     
         6 . The printed object of  claim 4  in which the first colored ink or design comprises a color selected from the color group consisting of: PANTONE 357 C, PANTONE 2945, PANTONE Violet and CMY. 
     
     
         7 . The printed object of  claim 1  in which the first colorant comprises Lithol Rubine. 
     
     
         8 . The printed object of  claim 7  in which the volume of weight ratio for the colored ink mixture comprises 24%-32% Lithol Rubine and 68%-76% opaque white. 
     
     
         9 . The printed object of  claim 7  in which the volume or weight ratio for the colored ink mixture comprises 78% opaque white and 22% Lithol Rubine. 
     
     
         10 . The printed object of  claim 1  in which the difference range comprises 12%-25%. 
     
     
         11 . The printed object of  claim 1  in which the first colored ink or design and the colored ink mixture comprise a spectral reflectivity difference of 12% or higher at 670 nm±10 nm. 
     
     
         12 . The printed object of  claim 1  in which the encoded signal comprises a sparse mark and carries a plural bit identifier payload. 
     
     
         13 . The printed object of  claim 1  in which at or around 660 nm comprises a spectral range of 620 nm-700 nm. 
     
     
         14 . 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 comprising a first area, a first colored ink or design printed within the first area, the first colored ink or design comprising a spectral reflectivity of less than or equal to 20% at or around 660 nm, a colored ink mixture printed over the first colored ink or design at a first plurality of spatial locations within the first area, the colored ink mixture printed such that the first area comprises a second plurality of spatial locations without the colored ink mixture, the colored ink mixture comprising opaque white ink and a first colorant, wherein the color ink mixture comprises a spectral reflectivity greater than the first colored ink or design at or around 660 nm, and wherein colored ink mixture comprises a spectral reflectivity less than the first colored ink or design in the range of 495 nm-570 nm, in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and in which the first colored ink or design and the colored 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 a plural-bit payload from the encoded signal;   outputting the plural-bit payload.   
     
     
         15 . The image processing method of  claim 14 , in which the colored ink mixture comprises Lithol Rubine, and the first colorant comprises Carbazole Violet. 
     
     
         16 . The image processing method of  claim 15  in which the colored ink mixture comprises by weight or volume 30%-42% Lithol Rubine, 8%-22% Carbazole Violet and 44%-56% Opaque White. 
     
     
         17 . The image processing method of  claim 16  in which the colored ink mixture comprises by weight or volume 36% Lithol Rubine, 14% Carbazole Violet and 50% Opaque White. 
     
     
         18 . The image processing method of  claim 16  in which the first colored ink or design comprises a color selected from the color group consisting of: PANTONE 357 C, PANTONE 2945, PANTONE Violet, and CMY. 
     
     
         19 . The image processing method of  claim 14  in which the first colored ink or design and the colored ink mixture comprise a spectral reflectivity difference of 12% or higher at 670 nm±10 nm. 
     
     
         20 . The image processing method of  claim 14  in which the encoded signal comprises a sparse mark and carries a plural bit identifier payload.