Spectral Difference Encoding in Standard Images

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Solution Overview

Problem

Current information coding techniques in images face challenges in achieving imperceptibility and robustness within the visible spectrum, particularly in devices that do not require special materials or illumination, and struggle to encode auxiliary information without impacting visual appearance or being detectable by standard cameras.

Innovation Solution

The method involves encoding information in spectral differences between colors that appear similar to the human visual system, using digital image processing to alter pixel values in standard color formats, and employing techniques like metameric pairs to create distinguishable spectra, which can be detected using appropriate capture and signal processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If information is encoded using visible spectrum techniques, then broad application to standard devices is achieved, but imperceptibility and robustness are compromised

Engineering Contradiction:

Improvebroad application to standard devicesVSAvoidimperceptibility and robustness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent transitions from encoding information in spatial or luminance dimensions to encoding in the spectral dimension. By exploiting differences in spectral power distributions across multiple wavelength bands, the system achieves both imperceptibility (since spectral differences are invisible to human vision) and robustness (since spectral signatures are inherent to the materials and illumination). This dimensional shift from 2D/3D spatial encoding to spectral encoding resolves the contradiction between visibility and reliability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention changes the fundamental parameters used for encoding from spatial coordinates or intensity values to spectral power distribution parameters across multiple wavelength bands. By representing image data in terms of spectral signatures rather than traditional RGB or grayscale values, the system can embed information in the spectral domain that is imperceptible to humans but detectable and robust for machine processing.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If spectral encoding techniques are used, then imperceptibility and robustness are improved, but special illumination and capture devices are required

Engineering Contradiction:

Improveimperceptibility and robustnessVSAvoidspecial illumination and capture devices

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent demonstrates that standard commercial cameras and illumination sources can be used for spectral encoding and decoding. The system processes standard RGB images to extract spectral power distribution information and embeds data in spectral differences that are detectable by conventional cameras. This universal approach eliminates the need for specialized multi-spectral or hyperspectral equipment while maintaining the benefits of spectral encoding.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention creates a spectral representation as a copy or transformation of standard image data. Instead of requiring direct multi-spectral capture, the system generates spectral power distribution estimates from conventional RGB images and uses these copies for encoding. This allows spectral encoding techniques to be applied to standard digital images without specialized capture equipment.

Inventive Principle:

Principle #26Copying

3Loss of information

If information is embedded in spectral differences, then information capacity and robustness increase, but detection and measurement difficulty increases

Engineering Contradiction:

Improveinformation capacityVSAvoiddetection of spectral differences

Core Design Contradiction:

Loss of informationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces complex spectral measurement instrumentation with standard camera-based imaging systems. By formulating the detection problem as an image processing task rather than a spectroscopic measurement task, the system uses well-established camera technology and image analysis algorithms to detect spectral differences, significantly reducing measurement difficulty while maintaining information capacity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for imperceptible yet detectable information encoding within images, usable across a wide range of devices and systems, including those operating in the visible spectrum, without requiring special materials or illumination, while maintaining visual quality and enabling broader applicability.

Implementation Method 1

Methodology Applied

Scientific EffectMetamerism:

Data Source

PatentUS10447888B2Information coding and decoding in spectral differences

Publication Date: 2019.10.15 DIGIMARC LLC

AI summary

Information is encoded in an image signal by exploiting spectral differences between colors that appear the same when rendered. These spectral differences are detected using image sensing that discerns the spectral differences. Spectral difference detection methods include using sensor-synchronized spectrally-structured-light imaging, 3D sensors, imaging spectrophotometers, and higher resolution Bayer pattern capture relative to resolution of patches used to convey a spectral difference signal.