Graphical Watermark Authentication on Curved Surfaces
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Solution Overview
Problem
Existing graphical watermark technologies struggle to accurately authenticate watermarks on curved surfaces, such as wine bottles, due to geometric distortions caused by the curvature, leading to unreliable authentication results.
Innovation Solution
A graphical watermark system that includes a plurality of graphical markers carrying position and pose information, and identity information, with a watermark pattern provided between pairs of graphical markers. This system allows for accurate authentication by correcting for both perspective and geometric distortions, even on curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If perspective correction is applied to correct geometric distortion on cylinder surfaces, then authentication reliability improves, but the system complexity increases due to additional correction requirements
Solution Approach 1:
The patent divides the correction process into two independent stages: perspective correction for planar distortion and geometric correction for cylindrical curvature. By segmenting the correction functions, the system can handle each type of distortion with dedicated algorithms, improving reliability without unnecessarily increasing overall system complexity.
Solution Approach 2:
The patent applies perspective correction as a preliminary step before geometric correction. This preliminary action normalizes the image to a planar view, making the subsequent cylindrical geometric correction more accurate and efficient. The preliminary correction simplifies the later correction process rather than complicating it.
2Measurement precision
If more markers are added to correct geometric distortion on cylinder surfaces, then measurement precision improves, but the quantity of required elements increases
Solution Approach 1:
The patent places markers at specific critical locations on the cylinder surface where geometric distortion is most pronounced, rather than uniformly distributing markers throughout the entire surface. This localized approach ensures precise correction at key distortion points while minimizing the total number of markers required.
Solution Approach 2:
The patent employs an asymmetric marker arrangement adapted to the cylindrical geometry, with markers positioned at locations that maximize their corrective effectiveness. This asymmetric placement optimizes the correction capability for the specific distortion patterns introduced by cylinder curvature, achieving high precision with fewer markers than symmetric uniform distributions would require.
3Adaptability or versatility
If geometric correction is performed without knowing cylinder size or camera parameters, then adaptability improves, but measurement precision deteriorates due to unknown parameters
Solution Approach 1:
The patent enables the system to automatically determine cylinder parameters and camera characteristics by analyzing the detected markers and their spatial relationships. The system self-calibrates by using the marker positions and known geometric relationships to compute the necessary correction parameters, eliminating the need for pre-provided cylinder size or camera parameter information while maintaining high correction precision.
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously refines its geometric correction by comparing the corrected image features against the original marker positions and detected cylinder geometry. This iterative feedback process allows the system to adapt to unknown parameters and improve measurement precision automatically, compensating for any initial parameter uncertainties.
Data Source
AI summary
The present disclosure provides a graphical watermark, a method and an apparatus for generating a graphical watermark, and a method and an apparatus for authenticating a graphical watermark. The graphical watermark includes: a plurality of graphical markers carrying position and pose information, and identity information of the graphical watermark; and a watermark pattern provided between a pair of graphical markers.