Spread Spectrum Image Reconstruction Under Ambient Light

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Solution Overview

Problem

Existing image processing methods fail to effectively reconstruct the shape of moving objects under relatively strong ambient light conditions using shot images.

Innovation Solution

An image processing method employing spread spectrum modulation light and filtering processing, where a light source irradiates an object with a spreading signal, and a camera captures and filters the reflected images to eliminate noise, allowing for the reconstruction of object shapes even under strong ambient light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional image processing methods are used to reconstruct object shape under ambient light, then the system can operate in outdoor conditions, but the measurement precision deteriorates due to noise from ambient light

Engineering Contradiction:
Improveoutdoor operation capabilityVSAvoidobject shape measurement precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies periodic modulation to the projected light signal, using a specific frequency that can be distinguished from ambient light. The light source modulates the projected pattern at a known frequency, and the imaging system uses synchronous detection at this frequency to extract the modulated signal from the ambient light noise, thereby maintaining measurement precision in outdoor conditions

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent introduces a band-pass filter as an intermediary component that selectively passes only the modulated frequency range while blocking ambient light frequencies. This filter acts as a mediator between the projected light signal and the imaging sensor, isolating the useful signal from the harmful ambient light interference

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the light intensity is increased to improve signal quality, then the object shape reconstruction accuracy improves, but the harmful effect of ambient light interference increases

Engineering Contradiction:
Improveobject shape reconstruction accuracyVSAvoidambient light interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

By modulating the light at a specific frequency and using synchronous detection, the system can achieve high measurement precision without increasing light intensity. The periodic modulation creates a distinctive signal signature that can be extracted from noise through frequency-selective detection, maintaining accuracy while avoiding the need for high-intensity illumination that would worsen ambient light interference

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes the frequency parameter of the projected light signal to a modulated frequency that is distinct from ambient light frequencies. This parameter change allows the system to differentiate between the projected signal and ambient light interference in the frequency domain, improving signal extraction efficiency without increasing light intensity

Inventive Principle:
Principle #35Parameter changes

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

Enables accurate measurement and reconstruction of both stationary and moving objects' shapes by eliminating noise caused by ambient light, ensuring clear image output.

Implementation Method 1

a light source (10) for irradiating light to the object (1) based on a spreading signal obtained by the spread spectrum modulation

Methodology Applied
Scientific EffectSpread spectrum modulation:

Implementation Method 2

an imaging apparatus (12) for receiving the reflected light from the surface of the object (1)

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3561447B1Image processing method
Publication Date: 2023.11.22 NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE & TECHNOLOGY
  • EP3561447B1 patent drawingFigure 1
  • EP3561447B1 patent drawingFigure 2
  • EP3561447B1 patent drawingFigure 3

AI summary

The shape of a moving object is reconstructed from a shot image under relatively-strong ambient light or an embedded image is demodulated from a video image in which an image that may not be visually recognized is embedded to display the image. The image processing method of the present invention includes (a) Step S1 of irradiating flashing light to the surface of the object based on a spreading signal obtained by spread spectrum modulation, (b) Step S2 of receiving reflected light from the surface of the object to output the signal including the image information, (c) Step S3 of a filtering for eliminating noise including a low-frequency component from the signal including the image information, (d) Steps S4 and S5 of inverse-spreading the signal after the filtering to demodulate the signal, and (e) Step S6 of outputting, based on a signal obtained by the demodulation, an image reflecting the state of the surface of the object.