In one embodiment, a method for 3D digital watermarking for a triangular mesh using one or more key parameters is disclosed including forming a Hamiltonian path of a desired length around a selected vertex in a selected direction of a spiral; marking the selected vertex a dead end if there is a deadlock and continuing the spiral; and applying a watermark by introducing points in a path order on edges of the spiral, wherein information is encoded at a partition of adjacent triangles at one or more of the points.

Provided is a method and apparatus for digital image watermarking. In the method and apparatus, a computer system receives a first image and receive information for embedding in the first image. The computer system preprocesses the first image to produce a preprocessed first image and preprocesses the information by at least channel-encoding the information to produce preprocessed information including a plurality of sets of bits. The computer system embeds the preprocessed information in the preprocessed first image by at least selecting a plurality of blocks of the preprocessed first image and embedding in each block of the plurality of blocks a respective set of bits of the plurality of sets of bits. Each set of bits of the plurality of sets of bits is embedded in a minimum number of blocks of the plurality of blocks, where the minimum number of blocks is greater than one.

An image processing method determines a geometric transform of a suspect image by efficiently evaluating a large number of geometric transform candidates in environments with limited processing resources. Processing resources are conserved by using complementary methods for determining a geometric transform of an embedded signal. One method excels at higher geometric distortion, and specifically, distortion caused by greater tilt angle of a camera. Another method excels at lower geometric distortion, for weaker signals. Together, the methods provide a more reliable detector of an embedded data signal in image across a larger range of distortion while making efficient use of limited processing resources in mobile devices.

Differential modulation schemes encode a data channel within host signal or noisy environment in a manner that is robust, flexible to achieve perceptual quality constraints, and provides improved data capacity. Differential arrangements enable a decoder to suppress host signal or other background signal interference when detecting, synchronizing and extracting an encoded data channel. They also enable the incorporation of implicit or explicit synchronization components, which are either formed from the data signal or are complementary to it.

Optical code signal components are generated and then transformed into signal bearing art that conveys machine readable data. The components of an optical code are optimized to achieve improved signal robustness, reliability, capacity and/or visual quality. An optimization program can determine spatial density, dot distance, dot size and signal component priority to optimize robustness. An optical code generator transforms tiles of an optical code or image embedded with the optical code into signal-bearing art using stipple, Voronoi, Delaunay or other graphic drawing methods so as to retain prioritized components of the optical code. The optical code is merged into a host image, such as imagery, text and graphics of a package or label, or it may be printed by itself, e.g., on an otherwise blank label or carton. A great number of other features and arrangements are also detailed.

A camera captures video imagery depicting a digitally-watermarked object. A reference signal in the watermark is used to discern the pose of the object relative to the camera, and this pose is used in affine-transforming and positioning a graphic on the imagery as an augmented reality overlay. Feature points are also discerned from the captured imagery, or recalled from a database indexed by the watermark. As the camera moves relative to the object, the augmented reality overlay tracks the changing object depiction, using these feature points. When feature point-based tracking fails, the watermark is again processed to determine pose, and the overlay presentation is updated accordingly. In another arrangement, feature points are extracted from images of supermarket objects captured by multiple users, and are compiled in a database in association with watermark data identifying the objectsserving as a crowd-sourced repository of feature point data. A great number of other features and arrangements are also detailed.

Imagery captured by an autonomous robot is analyzed to discern digital watermark patterns. In some embodiments, identical but geometrically-inconsistent digital watermark patterns are discerned in an image frame, to aid in distinguishing multiple depicted instances of a particular item. In other embodiments, actions of the robot are controlled or altered in accordance with image processing performed by the robot on a digital watermark pattern. The technology is particularly described in the context of retail stores in which the watermark patterns are encoded, e.g., on product packaging, shelving, and shelf labels. A great variety of other features and arrangements are also detailed.

A steganographic digital watermark signal is decoded from host imagery without requiring a domain transformation for signal synchronization, thereby speeding and simplifying the decoding operation. In time-limited applications, such as in supermarket point-of-sale scanners that attempt watermark decode operations on dozens of video frames every second, the speed improvement allows a greater percentage of each image frame to be analyzed for watermark data. In battery-powered mobile devices, avoidance of repeated domain transformations extends battery life. A great variety of other features and arrangements, including machine learning aspects, are also detailed.

In one embodiment, a method for 3D digital watermarking for a triangular mesh using one or more key parameters is disclosed including forming a Hamiltonian path of a desired length around a selected vertex in a selected direction of a spiral; marking the selected vertex a dead end if there is a deadlock and continuing the spiral; and applying a watermark by introducing points in a path order on edges of the spiral, wherein information is encoded at a partition of adjacent triangles at one or more of the points.

A phase deviation method determines an offset between a reference and suspect signal by analyzing a phase deviation surface created by computing a deviation metric for phase shift and then analyzing a surface formed from the deviation metrics for an array of offsets. The phase deviation method analyzes the deviation surface to determine an offset that minimizes phase deviation. This method is applied at increasing levels of detail to refine the determination of the offset.