Camera Distortion Feedback for Digital Watermarking

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Solution Overview

Problem

Digital watermarking in mobile devices faces challenges due to the low resolution and noise levels of typical mobile cell phone cameras, which affect the visibility and robustness of watermarks, and there is a need for efficient methods to adjust watermark embedding parameters based on camera quality to ensure effective detection.

Innovation Solution

A method using a programmed electronic processor to measure and quantify distortion introduced by cell phone cameras, providing feedback to adjust digital watermark embedding parameters, and determining metrics associated with different cameras to optimize watermark embedding, including measuring spatial frequency response (SFR) to estimate image quality distortion and predict watermark robustness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If digital watermarking is applied to mobile device cameras, then watermark embedding capability is provided, but low resolution and noise levels reduce watermark visibility and robustness

Engineering Contradiction:

Improvewatermark embedding capabilityVSAvoidwatermark detection reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system measures distortion characteristics of the mobile camera and uses these measurements to dynamically adjust watermark embedding parameters such as strength, frequency, and pattern. This allows optimization of watermark robustness specifically for the measured camera's distortion profile, resolving the contradiction between providing watermark capability and maintaining detection reliability despite low resolution and noise.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system implements a feedback loop where distortion measurements from the mobile camera are used to adjust subsequent watermark embedding operations. By measuring actual camera distortion and using this information to refine watermark parameters, the system adapts to the specific device characteristics, improving detection reliability while maintaining embedding capability.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If multiple print runs are conducted to optimize watermark detection, then detection accuracy improves, but time and resource consumption increase

Engineering Contradiction:

Improvewatermark detection accuracyVSAvoidtime for multiple print runs

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary distortion measurements on the mobile camera before actual watermark embedding and detection operations. By characterizing the camera's distortion properties in advance, the system can pre-optimize watermark parameters, eliminating the need for multiple iterative print runs and achieving accurate detection in a single operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces the mechanical trial-and-error process of multiple print runs with a computational approach based on distortion measurement and analysis. By using measured distortion data to calculate optimal watermark parameters, the system substitutes physical iteration with mathematical optimization, significantly reducing time and resource consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If watermark embedding parameters are adjusted based on camera quality, then watermark robustness improves, but process complexity increases

Engineering Contradiction:

Improvewatermark robustnessVSAvoidembedding process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system implements self-service by automatically measuring distortion characteristics and using these measurements to self-adjust watermark embedding parameters without requiring external intervention or complex manual configuration. The mobile camera itself provides the distortion data needed for optimization, simplifying the overall process while improving robustness.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system introduces distortion measurement as an intermediary step between camera characterization and watermark embedding. This intermediary measurement process provides quantitative data that bridges the gap between camera quality variations and optimal parameter selection, simplifying the adjustment process through objective measurement rather than complex heuristic reasoning.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9697578B2Assessment of camera phone distortion for digital watermarking

Publication Date: 2017.07.04 DIGIMARC LLC

AI summary

The present disclosure relates generally to cell phones and cameras, and to digital watermarking involving such cell phones and cameras. One claim recites a method comprising: measuring distortion introduced by a cell phone camera; using a programmed electronic processor, quantifying the distortion; and providing quantified distortion as feedback to adjust a digital watermark embedding process in view of the distortion introduced by the cell phone camera. The act of quantifying distortion may include, e.g., quantifying a spatial frequency response (SFR) of the cell phone camera. Of course, other claims and combinations are provided too.