Fourier Frequency Filtering for Radiograph Soft Tissue Contrast

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Radiographs often fail to clearly depict soft tissue structures, such as tendons and blood vessels, due to their low signal levels being masked by high background signals from bones, making it difficult for doctors to make reliable diagnoses.

Innovation Solution

An image processing method that involves storing radiographs in electronic form, performing a Fourier transformation, filtering the frequency-space intensity distribution by modifying the weighting between high-frequency and low-frequency image signal components based on the average structure size of the structures to be enhanced, and then applying an inverse Fourier transformation to improve perceptibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If contrast enhancement is applied to emphasise soft tissue structures, then the visibility of soft tissue improves, but the small signal fluctuations become lost in the high background signal of bones

Engineering Contradiction:

Improvecontrast enhancementVSAvoidsignal fluctuations

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The patent segments the frequency spectrum into different ranges and applies selective filtering to enhance specific frequency components corresponding to soft tissue structures while suppressing bone background signals. This segmentation in frequency space allows differential treatment of various tissue types.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transforms the image from position space to frequency space using Fourier transformation, enabling contrast enhancement in the frequency domain rather than directly in the spatial domain. This dimensional change allows manipulation of signal components without direct spatial distortion.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If standard image processing methods are used to enhance soft tissue visibility, then some soft tissue structures become clearer, but smaller bones imaged over larger bones remain scarcely perceptible

Engineering Contradiction:

Improvediagnostic reliabilityVSAvoiddetectability of small structures

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies local adaptive filtering that adjusts filtering parameters based on local image characteristics. Different regions of the image receive tailored filtering treatment, allowing small bones in specific locations to be enhanced without affecting other regions uniformly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The filtering parameters are dynamically adjusted based on the local frequency content and structure characteristics. The system adapts to different tissue types and sizes by modifying filter strength and frequency ranges, enabling detection of both small and large structures.

Inventive Principle:

Principle #15Dynamics

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 method enhances the contrast of poorly visible structures, allowing them to stand out more clearly against background structures, thereby improving diagnostic reliability by making subtle tissue differences more discernible.

Implementation Method 1

carrying out a Fourier transformation in order to determine a frequency-space intensity distribution

Methodology Applied

Scientific EffectFourier transformation:

Implementation Method 2

filtering the frequency-space intensity distribution by modifying the weighting between high-frequency and low-frequency image signal components

Methodology Applied

Scientific EffectFrequency filtering: Filter (optical)

Implementation Method 3

carrying out an inverse Fourier transformation of the filtered frequency-space intensity distribution, so as to obtain a modified position-space intensity distribution

Methodology Applied

Scientific EffectInverse Fourier transformation:

Data Source

PatentUS8244019B2Method and device for improving perceptibility different structures on radiographs

Publication Date: 2012.08.14 DURR DENTAL GMBH & CO KG

AI summary

The invention relates to a method for improving the perceptibility of different structures on radiographs by means of an image processing device consisting a) in storing a radiograph in electronic form as a local space-intensity distribution, b) in carrying out a Fourier transformation for determining a frequency-intensity distribution, c) in filtering said frequency-intensity distribution by modifying weighting between the high-frequency and low-frequency image signal components, wherein the fixing of the image signal components to be more intensively weighted is carried out taking into account the mean structure size of said structures whose perceptibility is to be improved, d) in carrying out an inverse Fourier transformation of the filtered frequency-intensity distribution in order to obtain a modified space-intensity distribution in which said structures are more easily perceptible. The image contrast for the hardly perceptible structures may be selectively improved by means of a changed weighting for the high-frequency, relative to the low-frequency, image signal components in the Fourier spectrum because the structures hardly perceptible on the radiographs, for example soft tissue parts having a size quantity and structuring different from easily perceptible structures as bones and implantants.