초록 ▼

Paper is textured with a pattern that yields a known signature signal when transformed to the frequency domain. This signature can be used for various purposes, including determining the angular orientation of the paper when scanned, conveying a plural-bit digital watermark, and for simple document

Paper is textured with a pattern that yields a known signature signal when transformed to the frequency domain. This signature can be used for various purposes, including determining the angular orientation of the paper when scanned, conveying a plural-bit digital watermark, and for simple document recognition purposes (e.g., photocopiers that refuse to reproduce banknotes). The texturing can be effected during the paper-making process, e.g., by shaping the surface of a de-watering element accordingly.

대표청구항 ▼

1. A method of determining a transformation of a paper document including: optically scanning the paper document to generate scan data; transforming the scan data to a frequency domain; identifying frequency components in the transformed scan data corresponding to texture resulting from the pap

1. A method of determining a transformation of a paper document including: optically scanning the paper document to generate scan data; transforming the scan data to a frequency domain; identifying frequency components in the transformed scan data corresponding to texture resulting from the paper's manufacture; and determining from said frequency components one or more possible transformations of the scanned documents from a reference state. 2. The method of claim 1 that includes determining from said frequency components a rotation of the scanned document from a reference orientation. 3. The method of claim 1 that includes determining from said frequency components a scale of the scanned document from a reference scale. 4. The method of claim 1 that includes determining from said frequency components a translation of the scanned document from a reference translation. 5. The method of claim 1 wherein the texture results from a de-watering element used in the paper's manufacture. 6. A method including: optically scanning a paper document to generate scan data; transforming the scan data to a frequency domain; identifying frequency components in the transformed scan data corresponding to texture resulting from the paper's manufacture; and interpreting said identified frequency components to yield payload data including at least a registration indicator. 7. The method of claim 6 that includes determining from the registration indicator a rotation of the scanned document from a reference orientation. 8. The method of claim 6 that includes determining from the registration indicator a scale of the scanned document from a reference scale. 9. The method of claim 6 that includes determining from the registration indicator a translation of the scanned document from a reference translation. 10. The method of claim 6 wherein the texture results from a de-watering element used in the paper's manufacture. 11. A paper-making process including: defining a frequency-domain signal, wherein the frequency-domain signal comprises an orientation component; inverse transforming the frequency-domain signal to yield a two-dimensional pattern in the spatial domain; shaping an element of the paper-making apparatus in accordance with said spatial domain pattern; and imparting said pattern to a paper surface, wherein the orientation component provides an orientation reference for paper made according to said paper-making process. 12. A printing process using paper made according to the method of claim 11, the printing process comprising: aligning printing on the paper so as to be oriented in a predetermined manner with respect to the pattern on the paper surface, wherein transforming optical scan data corresponding to said pattern into a frequency domain reveals an orientation of the paper.