Encoding data in an image
AssigneeHewlett-Packard Development Company, L.P.
InventorsPeter Morovic, Jan Morovic, Peter J. Klammer, James William Stasiak
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Abstract
Certain methods and systems are described for encoding data in an image. According to an example, a set of metamers under a first set of conditions may be determined that vary under a second set of conditions. These may be used to generate a set of color mappings for a sampled color value, each color mapping being used for a different data value in the data. As such the data values may be detectable when the image is observed under the second set of conditions but not detectable when the image is observed under the first set of conditions.
Claims11
A method of determining a set of color mappings for encoding data values in an image comprising:
- determining, for at least one sampled color in a first color space associated with a first set of conditions, a set of metamers for the sampled color, each metamer having a different representation in a second color space, the second color space being used to output the image;
- determining a range of color differences for the set of metamers under a second set of conditions;
- and
- determining a plurality of color mappings to the second color space for the at least one sampled color based on the range of color differences,
- wherein each color mapping in the plurality of color mappings is useable to encode a different data value in the image, and
- wherein the data values are detectable when the second set of conditions are applied to the image.
A method of encoding data comprising:
- receiving an image comprising pixels having color values in a first color space;
- receiving data to be encoded in the image;
- selecting one or more pixels to encode the data, wherein each pixel selected to encode the data is associated with a data value from the data;
- for each pixel selected to encode the data:
- selecting a metamer in a second color space based on the data value associated with the pixel, the metamer being selected from a plurality of metamers for a color value of the pixel under a first set of conditions, each data value having a different associated metamer in the second color space, each metamer having a different color metric under a second set of conditions;
- and
- outputting the image using the selected color representations,
- wherein the data is decodable from the image on application of the second set of conditions;
- and
- wherein the plurality of metamers comprise three or more color mappings and at least two of the plurality of metamers encode different non-zero data values.
Dependencies are inferred from the claim text.