Enhancing embedding of out-of-phase signals
First Claim
1. A method of steganographically hiding a first image in a second image, the second image comprising a plurality of color channels, wherein the hiding of the first image in the second image comprises at least hiding a first image component in a first of the plurality of color channels, and, at a second image location, hiding a component in a second of the plurality of channels, the second channel component being placed so as to offset visibility attributable at least a portion of the first channel component, said method comprising:
- analyzing an attribute of at least one of the plurality of color channels; and
based on the analysis, altering the first image component prior to embedding in the first and second color channels.
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Accused Products
Abstract
The present invention relates to steganographically hiding images and information. In a preferred embodiment, an image is hidden within a media signal. The media preferably includes a cyan (C) color plane, a magenta (M) color plane, a yellow (Y) color plane and a black (K) color plane. In an alternative embodiment, the media includes a spot color. The image is converted into a black color channel image and is then applied to the media'"'"'s K channel. The black channel image is inverted and the inverted image is applied to the media'"'"'s CMY (or spot) color planes. The C, M and/or Y channels can be investigated to determine whether the image'"'"'s signal level should be modified. In a related embodiment, the media signal is segmented into a plurality of blocks and the detection level of a first embedded block is determined to be sufficient before the embedding continues to a second block. In still another embodiment, visible spectrum detection of our out-of-phase digital watermark provides a clue as to whether a printing process needs calibration or is misaligned.
253 Citations
43 Claims
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1. A method of steganographically hiding a first image in a second image, the second image comprising a plurality of color channels, wherein the hiding of the first image in the second image comprises at least hiding a first image component in a first of the plurality of color channels, and, at a second image location, hiding a component in a second of the plurality of channels, the second channel component being placed so as to offset visibility attributable at least a portion of the first channel component, said method comprising:
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analyzing an attribute of at least one of the plurality of color channels; and
based on the analysis, altering the first image component prior to embedding in the first and second color channels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of steganographically hiding a digital watermark in an image, the image comprising a plurality of color channels including a black channel and a first color channel, said method comprising:
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segmenting the image into a plurality of blocks;
hiding a first digital watermark component in the black channel of a first of the plurality of blocks;
hiding the component in the first color channel of the first block, the first channel component being hidden so as to offset at least some portion of a visible artifact that is attributable to the component in the black channel;
detecting the digital watermark component; and
based on the digital watermark detection, reembedding the first block if the detection is below a predetermined threshold, and embedding a second of the plurality of blocks if the detection is above a predetermined threshold. - View Dependent Claims (14, 15, 16, 17)
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18. A method of monitoring a printing process, the printing process providing a print having at least a first color plane and a second color plane, wherein a digital watermark is steganographically embedded in the print by embedding at least a first digital watermark component in the first color plane and embedding at least a second digital watermark component in the second plane, the second plane component being embedded so as to reduce visible artifacts attributable to the first plane component, said method comprising:
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optically capturing a visible spectrum image of the print to provide corresponding scan data;
analyzing the scan data to determine whether a digital watermark component is detectable; and
signaling at least a printing misalignment when the digital watermark component is detected. - View Dependent Claims (19, 20, 21)
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22. A method of monitoring a printing process comprising:
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optically scanning a print produced by a printing process to generate scan data, wherein at least some of the scan data corresponds to the visible spectrum, and wherein the print comprises a first steganographic watermark component including a first plural-bit message and a second steganographic watermark component including a second plural-bit message embedded therein;
determining whether the first or second steganographic watermark components are detectable from the scan data; and
if at least one of the components is so detectable,signaling a printing discrepancy. - View Dependent Claims (23, 24, 25)
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26. A method of monitoring a printing process comprising:
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optically scanning a print produced by a printing process to generate scan data, wherein at least some of the scan data corresponds to the visible spectrum, and wherein the print comprises a first steganographic watermark component and a second steganographic watermark component embedded therein;
determining whether the first or second steganographic watermark components are detectable from scan data corresponding to the visible spectrum; and
if at least one of the components is so detectable,signaling a printing discrepancy, and wherein the first or second steganographic watermark components are intended only to be detectable from scan data corresponding to a non-visible spectrum absent a printing discrepancy.
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27. A method of steganographically hiding at least one fiducial in an image, the image comprising a plurality of color channels including a black channel and a first color channel, said method comprising:
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providing a first instance of a fiducial in the black channel at a first image area; and
providing a second instance of the fiducial in the color channel at the first image area, wherein the first instance and the second instance cooperate to reduce visibility of the fiducial in the image. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification