# US 2010/0164984 A1 · Method for Embedding Messages into Documents Using Distance Fields > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0164984 A1 - Document ID: US20100164984A1 - Status: Published application - Kind: A1 - Application number: 12/347,277 - Filed: 2008-12-31 - Published: 2010-07-01 - Earliest claimed: 2008-12-31 - Assignees: Mitsubishi Electric Research Laboratories, Inc. - Inventors: Shantanu Rane; Ronald N. Perry; Anthony Vetro - Web page: https://patentgrep.com/patent/US20100164984A1 ## CPC - H04N 1/32203: {Spatial or amplitude domain methods (H04N1/32309 takes precedence)} - G06T 11/23: using straight lines or curves - H04N 1/32208: {involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition (H04N1/32219, H04N1/32224 take precedence)} - H04N 1/32261: {in binary data (H04N1/32256 takes precedence)} - G09G 2358/00: Arrangements for display data security - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract A method embeds a message into a document containing a set of glyphs. Individual glyphs in the document, groups of glyphs in the document, or the entire document are represented using a distance field that includes distance values from the shapes of interest. Each symbol of the message is represented as modifications of a subset of the distance values in the distance field. This subset of the distance values in the distance field is modified according to modification to produce a modified glyph in a modified document, wherein the symbol in the message is embedded in the modified glyph. ## Claims ### Claim 1 A method for embedding symbols of a message into a document containing a set of glyphs, comprising: representing a glyph in a document as a distance field; representing a symbol in a message to be embedded in the document as a modification of a subset of values in the distance field; and modifying the subset of values in the distance field according to the modification to produce a modified glyph in a modified document, wherein the symbol in the message is embedded in the modified glyph. ### Claim 2 (depends on 1) The method of claim 1, wherein the distance field is a regularly sampled distance field. ### Claim 3 (depends on 1) The method of claim 1, wherein the distance field is an adaptively sampled distance field (ADF). ### Claim 4 (depends on 1) The method of claim 1, wherein the distance field is a set of values stored in a data structure in a memory device. ### Claim 5 (depends on 1) The method of claim 1, wherein the distance field includes procedures to reconstruct and render the glyph based on the message symbols to be embedded. ### Claim 6 (depends on 1) The method of claim 1, wherein the modification includes a deterministic modification and a probabilistic modification. ### Claim 7 (depends on 1) The method of claim 1, further comprising: selecting the subset of values in the distance field according to a key. ### Claim 8 (depends on 1) The method of claim 1, wherein the modification defines new values for the subset of values in the distance field. ### Claim 9 (depends on 1) The method of claim 1, wherein the modification defines correction values for the subset of values in the distance field. ### Claim 10 (depends on 1) The method of claim 1, wherein the modification defines correction values for a sampling density for the subset of values in the distance field. ### Claim 11 (depends on 1) The method of claim 1, further comprising selecting the subset of values in the distance field according to a local sampling density. ### Claim 12 (depends on 1) The method of claim 1, further comprising selecting the subset of values in the distance field according to locally computed gradients on a boundary of a shape of the glyph. ### Claim 13 (depends on 1) The method of claim 1, further comprising: inserting in the message at least one packetization symbol. ### Claim 14 (depends on 13) The method of claim 13, wherein the packetization symbol is selected from a group including a begin packet symbol, a packet number symbol, and a synchronization symbol. ### Claim 15 (depends on 1) The method of claim 1, further comprising: representing the modified glyph with a modified distance field including modified distance values; detecting an embedded modification associated with a subset of the modified distance values in the modified distance field; and determining the symbol of the message based on the embedded modification. ### Claim 16 (depends on 15) The method of claim 15, further comprising: determining the subset of the modified distance values according to a key. ### Claim 17 (depends on 15) The method of claim 15, further comprising: determining the subset of the modified distance values according to a database of shape elements of glyphs. ### Claim 18 A method for embedding a message into a document, comprising: representing at least part of a document as a distance field including distance values; representing a symbol in a message to be embedded in the document as a modification of a subset of the values in the distance field; and modifying the subset of the values in the distance field according to the modification to produce a modified document, wherein the symbol in the message is embedded in the modified document. ### Claim 19 (depends on 18) The method of claim 18, wherein the subset of values in the distance field is associated with a glyph in the document. ### Claim 20 (depends on 18) The method of claim 18, further comprising: processing the modified document. ### Claim 21 (depends on 20) The method of claim 20, wherein the processing is selected from the group including rendering, copying, printing, faxing, emailing, displaying, scanning of the modified document, file transferring of the modified document or combinations thereof. ### Claim 22 (depends on 18) The method of claim 18, further comprising: selecting the subset of values in the distance field according to a key. ### Claim 23 (depends on 18) The method of claim 18, further comprising: representing the modified document with a modified distance field; detecting a modification associated with a subset of the modified distance values in the modified distance field; and determining the symbol of the message based on the modification. ### Claim 24 (depends on 23) The method of claim 23, further comprising: determining the subset of values in the modified distance field according to a key. ### Claim 25 (depends on 23) The method of claim 23, further comprising: determining the subset of values in the modified distance field according to a database of shape elements of glyphs. ### Claim 26 A method for embedding a message into a document, comprising: representing a glyph in a document as a distance field including distance values; mapping the distance values in the distance field to a set of density values; representing a symbol in a message to be embedded in the document as modification of a subset of the set of density values; and modifying the subset of the set of density values according to the modification to produce a modified document, wherein the symbol in the message is embedded in the modified document. ### Claim 27 (depends on 26) The method of claim 26, wherein the set of density values represents intensities of pixels of the glyph in the document. ### Claim 28 (depends on 26) The method of claim 26, wherein the set of density values represents colors of the glyph in the document. ### Claim 29 (depends on 26) The method of claim 26, wherein the set of density values represents texture of the glyph in the document. ### Claim 30 (depends on 26) The method of claim 26, further comprising: selecting the subset of the set of density values according to color-fringing artifacts of a display device, wherein the display device uses addressable pixel components. ### Claim 31 (depends on 26) The method of claim 26, further comprising: selecting the subset of the set of density values according to a aliasing artifact of a display device, wherein the aliasing artifact is associated with a display position of the glyph. ### Claim 32 (depends on 26) The method of claim 26, further comprising: selecting the subset of the set of density values according to a key.