Xerox Corporation

Google Inc.

William James Rucklidge

Daniel P Huttenlocher

Daniel Gureasko Bobrow

James V Mahoney

John Seely Brown

David Goldberg

James Douglass Thornton

Eric W Jaquith

Soohyun Bae

Pedro Felzenswalb

Systems and methods for adjusting a camera parameter associated with a plurality of two-dimensional images are provided. Matched features can be selected as constraints for bundle adjustment using a graph model constructed based on the matched features. The graph model can have a plurality of nodes including a source node, a sink node, a point node for every matched feature, and a pose pair node associated with each pose pair viewing a matched feature. The graph model can include a plurality of edges interconnecting the plurality of nodes in the graph model. Each of these edges can be assigned a capacity and a cost based on various parameters. A flow can be computed through each of the edges of the graph model using, for instance, a minimum-cost maximum-flow algorithm. Matched features can be selected for bundle adjustment based on the flows of the edges in the graph model.

Adjusting camera parameters associated with a plurality of images

A watermark is embedded in a document having a plurality of pages. The pages of the document are analyzed to produce watermark information, which indicates whether the page is suitable for use with one or more of a plurality of watermarking schemes. The plurality of watermarking schemes may include page element shifting, flyspecking and text warping. An identifier (ID) is established, the ID associating the document with a user receiving the document. The ID is embedded in the pages of the document using the plurality of watermark schemes according to the watermark information. To recover an ID from a document, the pages of the document are analyzed to identify watermark information associated with the document. Embedded watermarks are recovered from the pages using the watermark information.

Watermarking digital documents

A system and method for generating a signed hardcopy document and authentication thereof is provided. A data representation including digital data is recorded from a hardcopy document. The digital data is compressed using a compression scheme including one of low-fidelity compression and symbol-based compression. An authentication token is generated from the compressed digital data. The authentication token is encoded. A signed hardcopy document including both the encoded authentication token and the data representation is printed.

System and method for generating a signed hardcopy document and authentication thereof

A system authenticates an original hardcopy document using a digital signature generation system and a digital signature verification system. Initially, the original hardcopy document is scanned to provide a bitmap image to the signature generation system. The bitmap image is highly compressed by the signature generation system using compression schemes such as MPEG (for gray images) or a low-fidelity symbol based compression scheme (for bi-level images). A signed hardcopy document is then printed that includes the bitmap image and an authentication token. The authentication token is encoded in the signed hardcopy document using either serpentine halftone patterns or data glyphs. The authenticity of the signed hardcopy document is verified by inputting a scanned bitmap image of the signed hardcopy document into the signature verification system. Once received, the signature verification system decodes, authenticates, and decompresses the bitmap image to define decompressed image data. The decompressed image data is then output to a display or printer and compared with the signed hardcopy document to determine whether it is authentic.

System for authenticating hardcopy documents

In a document search and retrieval system, document images are segmented into layout objects. Each layout object identifies different structural elements in a document image. In addition, the system computes attributes and features for each segmented layout object. Before any document images are transmitted between a client and a server, users specify which document image attributes and features are most relevant to their browsing or searching tasks. Transmission (and/or display) of document images is then divided into two stages. During the first stage, those layout objects which are identified as having the specified features or attributes are transmitted at a first or high resolution; the remaining layout objects in an image are transmitted at a second or lower resolution (or in the form of bounding polygons). If the second stage is invoked, those remaining layout objects are re-transmitted at the first or high resolution. The second stage of transmission may be invoked when either a user request is received or when there is a system timeout.

Transmission of subsets of layout objects at different resolutions

A programming interface of document search system enables a user to dynamically specifying features of documents recorded in a corpus of documents. The programming interface provides category and format flexibility for defining different genre of documents. The document search system initially segments document images into one or more layout objects. Each layout object identifies a structural element in a document such as text blocks, graphics, or halftones. Subsequently, the document search system computes a set of attributes for each of the identified layout objects. The set of attributes are used to describe the layout structure of a page image of a document in terms of the spatial relations that layout objects have to frames of reference that are defined by other layout objects. Using the set of attributes a user defines features of a document with the programming interface. After receiving a feature or attribute and a set of document images selected by a user, the system forms a set of image segments by identifying those layout objects in the set of document images that make up the selected feature or attribute. The system then sorts the set of image segments into meaningful groupings of objects which have similarities and/or recurring patterns. Subsequently, document images in the set of document images are ordered and displayed to a user in accordance with the meaningful groupings.

Sorting image segments into clusters based on a distance measurement

A processor is provided with a first set of digital information that includes a first structured representation of a document. From the first set of digital information, the processor produces a second set of digital information that includes a second structured representation of the document. The second structured representation is a lossless representation and includes a set of tokens and a set of positions. At least one token in the plurality of tokens has an associated semantic label which may be a character code associated with various font types in the second structured representation of the document. The semantic label may be obtained and stored in the second structured representation of the document by a computer program. The first and second representations may be resolution dependent structured representations and have, respectively, first and second characteristic resolutions. The first representation, but not the second, is provided in digital form to an untrusted recipient. A search for particular content of the second representation, including semantic labels, is requested by the recipient. A highlighted version of the first representation of the document is then provided to the recipient.

Relabelling of tokenized symbols in fontless structured document image representations

A technique that partially encrypts tokenized documents is disclosed. An electronic document image is generated from the document. A plurality of tokens are stored as a dictionary, wherein the tokens represent shapes contained in the document. A plurality of triples comprising a token identification (ID) and a corresponding position are generated from the document image, such that the token ID identifies a token from the dictionary that corresponds to a shape in the document image at the corresponding position. The token IDs are encrypted. The output representation for the secured document comprises encrypted token IDs, positions and a dictionary of tokens. Encoding techniques that reduce the size of the secured document are also disclosed. A trusted image output terminal, for use in document reconstruction, includes a single integrated circuit that performs the decrypting function and the page rendering function to significantly reduce the ability to capture the electronic document in the clear.

Methods and apparatus for partial encryption of tokenized documents

The present invention is directed to a system for finding a transformation of a gray level pattern in an image. The system recursively searches a transformation space in a multi-resolution manner. At each resolution, the transformation space is divided into groups of translations. For each group, a set of difference values are computed and compared against a previously known best difference value. If any of the computed difference values are greater than the previously known best difference value, the corresponding group of translations is removed from further consideration.

Efficient search for a gray-level pattern in an image using ranges of sums

A method for image processing including segmenting document images into text and continuous tone regions is provided. The method uses a token shape comparison and resultant data (e.g. shape recurrence) to determine which high-contrast regions of the image correspond to text or other symbols. The identified text is then separated from the image and processing ensues.

Method and apparatus for image processing employing image segmentation using tokenization

Relabeling of tokenized symbols in fontless structured document image representations

The present invention is directed to a system for finding a transformation of a gray-level pattern in an image. The system recursively searches a transformation space in a multi-resolution manner. At each resolution, the transformation space is divided into groups of transformations. For each group, pixels in the pattern are compared to neighborhoods of pixels in the image in order to identify whether a specific pattern pixel is within the minimum and maximum values of a neighborhood of pixels.

Efficient search for a gray-level pattern in an image

A method and apparatus for compressing a corpus of document images into a collective tokenized representation. Initially, documents in the corpus are individually compressed into a document tokenized format. A document image in the document tokenized format is represented using a symbol table and a table of positions. Each symbol in the symbol table is a shape in the original document image. The positions in the table of positions indicates where the symbols in the symbol table are placed to form the document image. Subsequently, the individual symbol tables of each document in the corpus are assembled to form clusters of similar shapes. These clusters are then analyzed to identify the degree of interrelationship between the symbols in the individual symbol tables. Individual document symbol tables with a large number of recurring symbols are grouped together. For each of the groups of symbol tables, a collective symbol table is computed. The collective symbol table improves the compression ratio of a corpus by eliminating redundant shapes appearing in the individual document symbol tables. Also, the collective symbol table advantageously identifies groupings of documents in the corpus which are related because a significant number of similar shapes are used in each of the documents.

System for performing collective symbol-based compression of a corpus of

A method in which first and second representations of a document are provided, for example, by being made available on one or more server computers connected to a computer network, such as the Internet or a corporate intranet. The first and second representations are resolution-dependent structured representations and have, respectively, first and second characteristic resolutions, the second resolution being greater than the first. The first representation, but not the second, is provided in digital form to an untrusted recipient. For example, the first representation can be transmitted through the network from the server on which the first representation is available to a client computer connected to the network. The second representation is converted to a third representation of the document, the third representation being a representation in a human-readable, nondigital form. For example, the second representation can be transmitted through the network in a secure manner to a trusted printing facility connected to the network. The trusted facility can then produce the third representation, for example by printing a hardcopy representation of the document. Finally, the third representation, but not the second, is provided to the untrusted recipient, for example, by physically transferring the third representation to the untrusted recipient.

Growing community of inventors

Mountain View, CA, United States of America

William James Rucklidge