Multi-Wavelength Fundus Processing to Isolate Choroidal Vessels

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Solution Overview

Problem

Existing methods struggle to effectively enhance and analyze choroidal blood vessels due to the interference of retinal blood vessels in fundus images, which hinders accurate diagnosis and analysis.

Innovation Solution

A method involving the use of multiple wavelength lights (G, R, and IR) to capture fundus images, followed by image processing techniques like black-hat filtering and contrast enhancement to isolate and enhance choroidal blood vessels by removing retinal blood vessels from the R fundus image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If retinal blood vessels are enhanced in fundus images, then retinal vessel visibility is improved, but choroidal blood vessel analysis is hindered due to interference

Engineering Contradiction:

Improveretinal blood vessel visibilityVSAvoidchoroidal blood vessel analysis accuracy

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The patent segments the fundus image into multiple wavelength components (first wavelength image and second wavelength image) to separate retinal blood vessels from choroidal blood vessels. By processing each wavelength component separately and combining them, the method achieves both retinal vessel enhancement and choroidal vessel analysis without mutual interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different image processing characteristics to different wavelength components. The first wavelength image (e.g., red) enhances retinal blood vessels with specific processing, while the second wavelength image (e.g., green or blue) preserves choroidal blood vessel information. This local quality differentiation allows simultaneous optimization for both vessel types.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If multiple wavelength images are processed to isolate choroidal blood vessels, then choroidal vessel visualization is improved, but processing complexity increases

Engineering Contradiction:

Improvechoroidal blood vessel visualization clarityVSAvoidimage processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary actions by capturing multiple wavelength images simultaneously or sequentially before final processing. The fundus imaging device collects first and second wavelength images in advance, which are then processed through subtraction or combination operations to isolate choroidal blood vessels, reducing the complexity of real-time processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses an intermediary processing step where the first wavelength image serves as a reference to remove retinal blood vessel components from the second wavelength image. This intermediary approach (subtraction or differential processing) simplifies the isolation of choroidal vessels compared to direct processing of single images.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 clearer visualization and analysis of choroidal blood vessels, reducing the interference from retinal blood vessels and improving diagnostic accuracy.

Implementation Method 1

photographing a fundus using first light having a first wavelength, and on a second fundus image obtained by photographing the fundus using second light having a second wavelength that is shorter than the first wavelength

Methodology Applied

Scientific EffectLight absorption and reflection: Absorption (EM radiation)

Data Source

PatentUS12423784B2Image processing method, program, ophthalmic device, and choroidal blood vessel image generation method

Publication Date: 2025.09.23 NIKON CORP

AI summary

An image processing method comprising acquiring a first fundus image obtained by photographing a fundus using first light having a first wavelength, and a second fundus image obtained by photographing the fundus using second light having a second wavelength that is shorter than the first wavelength; specifying, in the first fundus image, respective positions of retinal blood vessels appearing in the second fundus image; and generating a choroidal blood vessel image by processing the positions identified in the first fundus image.