Radiographic Image Processing Device Noise Suppression Edge Preservation
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Solution Overview
Problem
Radiographic images with low signal-to-noise ratios (S/N ratios) face challenges in suppressing graininess while preserving edges, as existing methods often result in reduced contrast and buried edges due to high noise levels.
Innovation Solution
A radiographic image processing device and method that acquire two images with different S/N ratios, derive a graininess suppression process for each, and apply an edge-preserving smoothing filter using a bilateral filter with weights based on pixel value differences to effectively suppress noise while maintaining edge integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a smoothing process is performed on a radiographic image with low S/N ratio to suppress graininess, then noise is reduced, but the contrast of edges is reduced and edges are buried in noise
Solution Approach 1:
The patent performs frequency conversion on the radiographic image to create band images indicating frequency components in different frequency bands before performing the smoothing process. This preliminary action allows the system to separate noise frequencies from edge frequencies, enabling selective smoothing that suppresses graininess while preserving edge contrast. The edge direction detection is performed on the band image, and smoothing is applied only along edge directions, preventing edge blur.
Solution Approach 2:
The patent applies different processing strategies to different frequency components of the image. By converting to frequency bands and detecting edge directions, the system applies smoothing locally only in regions and directions where edges are present, while maintaining higher frequencies in regions where edges are not present. This local quality approach ensures that graininess is suppressed where appropriate without compromising edge contrast.
2Object-affected harmful factors
If the dose of radiation is reduced to minimize exposure to the subject, then radiation safety is improved, but the amount of noise in the radiographic image increases
Solution Approach 1:
The patent converts the harmful noise introduced by low-dose radiation into a manageable problem through frequency-domain processing. By transforming the image to frequency bands, the system can identify and selectively remove noise frequencies while preserving useful signal frequencies corresponding to anatomical structures. This allows low-dose images to be processed to achieve quality comparable to higher-dose images.
Solution Approach 2:
The patent replaces direct physical dose reduction with computational processing to achieve noise suppression. Instead of relying solely on increasing radiation dose to reduce noise, the system uses frequency conversion and directional filtering algorithms to mathematically separate and remove noise, substituting a computational approach for a physical one.
Data Source
AI summary
A processor acquires a first radiographic image and a second radiographic image that include the same subject and have different S/N ratios. The processor derives a processing content of a first graininess suppression process on the first radiographic image having a higher S/N ratio of the first radiographic image and the second radiographic image and derives a processing content of a second graininess suppression process on the second radiographic image on the basis of the processing content of the first graininess suppression process. The processor performs a graininess suppression process on the second radiographic image on the basis of the processing content of the second graininess suppression process.