Embedding digital watermarks in spot colors
First Claim
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1. A method comprising:
- providing a digital watermark component comprising luminance value adjustments;
converting the luminance value adjustments to intensity value adjustment; and
adjusting a spot color signal comprising a set of intensity values with the digital watermark component, the component comprising the intensity value adjustments.
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Abstract
The present invention relates to digitally watermarking spot colors. Spot colors are represented as digital files including a set of intensity values. These intensity values correspond to the amount or percentage of spot color ink that should be applied to a pixel, a group of pixel or to an image area. A watermark signal component including luminance value adjustments is converted to intensity value adjustments. These intensity value adjustments are applied to the spot color digital file to facilitated digital watermark embedding. In another embodiment, an adjustment is made to the intensity values to compensate for noise introduced by a scanner, camera or color conversion.
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Citations
15 Claims
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1. A method comprising:
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providing a digital watermark component comprising luminance value adjustments;
converting the luminance value adjustments to intensity value adjustment; and
adjusting a spot color signal comprising a set of intensity values with the digital watermark component, the component comprising the intensity value adjustments. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method comprising:
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providing a spot color;
determining a first multicolor approximation of the spot color;
calculating an adjustment factor from the first multicolor approximation; and
modifying a digital watermark signal according to the adjustment factor. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A method comprising:
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analyzing a spot color with a spectrophotometer;
forming a spot color signature relating to the analysis; and
providing the spot color signature to verify the authenticity of materials printed with the spot color.
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Specification