Methods and systems for signal processing

Patent metadata

Field	Value
Publication number	US-9477884-B2
Application number	US-201313918559-A
Country	US
Kind code	B2
Filing date	Jun 14, 2013
Priority date	Jun 14, 2012
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

An object (e.g., a driver's license) is tested for authenticity using imagery captured by a consumer device (e.g., a mobile phone camera). Corresponding data is sent from the consumer device to a remote system, which has secret knowledge about features indicating object authenticity. The phone, or the remote system, discerns the pose of the object relative to the camera from the captured imagery. The remote system tests the received data for the authentication features, and issues an output signal indicating whether the object is authentic. This testing involves modeling the image data that would be captured by the consumer device from an authentic object—based on the object's discerned pose (and optionally based on information about the camera optics), and then comparing this modeled data with the data sent from the consumer device. A great variety of other features and arrangements are also detailed.

First claim

The invention claimed is:

1. A method comprising the acts:
receiving data corresponding to an image of a subject that was earlier encoded with a digital watermark signal to redundantly encode message data, said image having been captured by a camera of a consumer device;
processing the received data to yield output data, by: (a) discerning pose information indicating relative positioning of the subject and the camera; and (b) subtracting elements of the received data from each other to determine intra-image gradient information, said processing being performed by a processor in the consumer device configured to perform such act;
sending the pose information, and less than half of the determined intra-image gradient information, to a remote system; and
receiving response information, the response information being based on information decoded from the gradient information through use of (a) the sent pose information (b) the sent intra-image gradient information, and (c) key information not known to the consumer device;
wherein the method further includes:
receiving, from the remote system, data identifying N locations within the image;
identifying intra-image gradient information for these N locations, said identified information comprising said sent intra-image gradient information; and
sending said identified intra-image gradient information for these N locations to the remote system;
wherein the remote system is provided intra-image gradient information for only an incomplete subset of locations in the image.

2. The method of claim 1 that further includes:
receiving, from the remote system, data identifying N locations within the image, and for each of said N locations an associated direction;
identifying N intra-image gradients, each of said gradients corresponding to one of said N locations and its associated direction, said identified gradients comprising said sent intra-image gradient information; and
sending said identified intra-image gradient information to the remote system.

3. The method of claim 1 in which the act of sending comprises sending between 5% and 50% of the determined intra-image gradient information, to the remote system.

4. A method comprising:
receiving data corresponding to an image of a subject that was earlier encoded with a digital watermark signal to redundantly encode message data, said image having been captured by a camera of a consumer device;
processing the received data to yield output data, by: (a) discerning pose information indicating relative positioning of the subject and the camera; and (b) subtracting elements of the received data from each other to determine intra-image gradient information, said processing being performed by a processor in the consumer device configured to perform such act;
sending the pose information, and less than half of the determined intra-image gradient information, to a remote system; and
receiving response information, the response information being based on information decoded from the gradient information through use of (a) the sent pose information (b) the sent intra-image gradient information, and (c) key information not known to the consumer device;
wherein:
the subject includes features printed thereon that are too small to be resolved in the camera image of the subject; and
the response information includes data indicating said features are present on the subject.

5. The method of claim 4 in which the features comprise features that have a resolution finer than 3000 dpi.

6. The method of claim 4 in which the ultra-fine features comprise features that have a resolution finer than 6000 dpi.

7. The method of claim 4 in which the ultra-fine features comprise features that have a resolution finer than 9000 dpi.

8. The method of claim 4 in which the ultra-fine features comprise features that have a resolution finer than 11,000 dpi.

9. The method of claim 4 that includes, at the remote system:
from the sent pose information, modeling how the features—if present in the subject—would be manifested in the image data captured by the camera of the consumer device;
judging the sent intra-image gradient information based on a result of said modeling, to determine whether the subject includes said features, and producing result data corresponding thereto; and
sending at least some of said result data to the consumer device.

10. The method of claim 9 that includes:
at the remote system, receiving information about the camera comprising at least one of:
an identifier by which a camera model can be determined;
whether the camera applies image compression; and
a modulation transfer function of a camera lens; and
using said received information in connection with said modeling.

11. The method of claim 9 that includes, at the remote system, using the sent pose information to extract digital watermark payload data from the sent intra-image gradient information.

12. The method of claim 4 in which the act of sending comprises sending between 5% and 50% of the determined intra-image gradient information, to the remote system.

13. A digital watermark decoding method comprising the acts:
receiving image data corresponding to an image of a subject that was earlier encoded with a digital watermark signal to redundantly encode message data, said digital watermark signal including registration components, said image having been captured by a camera of a consumer device;
processing the received data to discern pose information indicating relative positioning of the subject and the camera by reference to said registration components, said processing act being performed by a processor in the consumer device configured to perform such act;
determining a set of intra-image gradient information by determining, for each of plural pixels in said image, a datum indicating whether a value of said pixel is greater-than or less-than values of one or more neighboring pixels, said determining act also being performed by said processor in the consumer device;
sending the pose information, and less than half of the intra-image gradient information, from the consumer device to a remote system; and
receiving response information at the consumer device, the response information being based on information decoded by the remote system from the digital watermark signal through use of (a) the pose information that was discerned by reference to said registration components, (b) the sent intra-image gradient information, and (c) key information available to the remote system;
wherein the key information is known to the remote system but not to the consumer device, and the image data is known to the consumer device but not to the remote system, thereby deterring system hacking and aiding user privacy.

14. The method of claim 13 wherein the method further includes the acts:
receiving, from the remote system, data identifying N locations within the image;
identifying intra-image gradient information for pixels at these N locations, said identified information comprising said set of intra-image gradient information; and
sending said identified intra-image gradient information to the remote system;
wherein the remote system is provided intra-image gradient information for only an incomplete subset of locations in the image.

15. The method of claim 13 wherein the subject includes features printed thereon that are too small to be resolved in the camera image of the subject, and the response information includes data indicating said features are present on the subject.

16. The method of claim 15 wherein the subject inclu

Assignees

• Digimarc Corp

Inventors

• Rhoads Geoffrey B

Classifications

• G06T1/0021

  Image watermarking · CPC title

• G06T1/0064 Primary

  Geometric transfor invariant watermarking, e.g. affine transform invariant · CPC title

• G06T2201/0051

  Embedding of the watermark in the spatial domain · CPC title

• G09C5/00

  Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages · CPC title

• G06T2201/0601

  whereby calibration information is embedded in the watermark, e.g. a grid, a scale, a list of transformations · CPC title