Image Processing Device MTF Matching for Axial Chromatic Aberration

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Solution Overview

Problem

Conventional chromatic aberration correction devices struggle with stable correction of axial chromatic aberration in single-plate image sensors like Bayer arrays, as they rely on interpolation algorithms that can introduce color artifacts and mismatched Modulation Transfer Function (MTF) characteristics, leading to unpredictable image restoration and unnatural color artifacts.

Innovation Solution

An image processing device that matches MTF characteristics between color components by interpolating missing color components and applying smoothing or sharpening processes to correct MTF mismatches, using a reference color component to align MTF characteristics, thereby stabilizing axial chromatic aberration correction and preventing color bleeding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If interpolation algorithms are used to create a color image with all three colors for axial chromatic aberration correction, then color information is complete for correction, but color artifacts increase and correction stability decreases

Engineering Contradiction:
Improvecolor information completenessVSAvoidcorrection stability
Core Design Contradiction:
Loss of informationVSReliability

Solution Approach 1:

The patent applies smoothing or sharpening filters to color planes before interpolation to pre-correct MTF mismatches. This preliminary action ensures that when colors are interpolated, the MTF characteristics are already aligned, preventing color artifacts and ensuring stable correction throughout the process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent dynamically adjusts filtering parameters (smoothing or sharpening strength) based on the detected MTF mismatch between color planes. By changing these parameters adaptively, the system optimizes the balance between suppressing color artifacts and maintaining correction effectiveness across different imaging conditions.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If smoothing or sharpening filters are applied to color planes to correct MTF mismatch, then axial chromatic aberration correction improves, but color artifacts and false structures increase

Engineering Contradiction:
ImproveMTF matching accuracyVSAvoidcolor artifacts
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent uses correlation calculation between color planes as feedback to determine the appropriate filtering strength. The system continuously monitors the MTF mismatch level and adjusts the smoothing or sharpening parameters accordingly, increasing filter strength when MTF mismatch is high and reducing it when mismatch is low, thereby minimizing color artifacts while maintaining correction accuracy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent implements dynamic filtering where the smoothing or sharpening parameters are not fixed but adapt to the local image characteristics and MTF mismatch conditions. This dynamic approach allows the system to apply stronger filtering only where necessary, preserving fine details and reducing false structures in regions where they are not needed.

Inventive Principle:
Principle #15Dynamics

3Object-generated harmful factors

If filtering is increased to suppress color artifacts, then color artifact reduction improves, but local color bleeding extends widely and image restoration deviates from original MTF state

Engineering Contradiction:
Improvecolor artifact suppressionVSAvoidimage restoration accuracy
Core Design Contradiction:
Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies partial filtering by selectively smoothing or sharpening only the specific color planes that exhibit MTF mismatch, rather than uniformly filtering all color planes. This partial action approach suppresses color artifacts in affected regions while preserving the original MTF characteristics in regions where mismatch is minimal, maintaining overall image restoration accuracy.

Inventive Principle:
Principle #16Partial or excessive action

4Measurement precision

If parameter search is performed to maximize correlation between color planes, then correction optimization improves, but specific interpretation techniques for correlation are lacking

Engineering Contradiction:
Improvecorrelation maximizationVSAvoidcorrelation interpretation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs self-service by using the image data itself to calculate correlation between color planes and determine filtering parameters. The system automatically extracts MTF mismatch information from the captured image and uses this self-derived information to guide the correction process, eliminating the need for external calibration data or complex manual interpretation techniques.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS8509533B2Image processing device and image processing method
Publication Date: 2013.08.13 NIKON CORP
  • US8509533B2 patent drawing
  • US8509533B2 patent drawing
  • US8509533B2 patent drawing

AI summary

An image processing device that converts a first image captured via an optical system in which at least one of a plurality of color components is missing in one pixel and MTF characteristics are different between a reference color component and at least one missing color component at an imaging plane, into a second image in which MTF characteristics are matched, includes: an image creation unit that acquires information concerning differences in MTF characteristics between the missing color component and the reference color component in a pixel having the missing color component of the first image and creates the second image by using the acquired information.