Image Processing Noise Reduction and Resolution Enhancement

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Solution Overview

Problem

Existing image restoration processes amplify noise, leading to degraded image quality and reduced effectiveness in resolution enhancement, while existing noise reduction methods can deteriorate edges or leave residue noise.

Innovation Solution

An image processing apparatus that performs a resolution enhancement process followed by a noise reduction process, using a non-local means filter with weights calculated based on correlation values and noise gain characteristics to effectively reduce noise amplified during the enhancement process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resolution enhancement process is performed to correct degraded captured images, then the resolution of the captured image is improved, but noise is remarkably amplified

Engineering Contradiction:

ImproveresolutionVSAvoidnoise amplification

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies a noise reduction process before the resolution enhancement process. By preprocessing the degraded image to reduce noise content before performing resolution enhancement, the subsequent enhancement operates on a cleaner image, preventing excessive noise amplification while still achieving resolution improvement. This preliminary action resolves the contradiction by addressing the noise issue before it can be amplified by the enhancement process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of noise by using the noise characteristics to inform the resolution enhancement process. The noise reduction step transforms the noisy degraded image into a cleaner intermediate image, which then serves as the basis for resolution enhancement. This approach turns the initially harmful noise into a manageable factor that can be addressed in the processing pipeline, allowing both noise control and resolution improvement.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Measurement precision

If the gain is increased by reducing Γ of the Wiener filter to improve resolution enhancement effect, then the resolution enhancement effect improves, but noise is remarkably amplified

Engineering Contradiction:

Improveresolution enhancement effectVSAvoidnoise amplification

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent performs noise reduction before resolution enhancement, which allows for more aggressive resolution enhancement parameters to be used. By preprocessing to reduce noise, the system can increase the gain in the resolution enhancement step without suffering from excessive noise amplification, as the noise has already been mitigated in the preliminary noise reduction stage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the image processing into distinct stages: noise reduction followed by resolution enhancement. This segmentation allows each process to be optimized independently - the noise reduction stage handles noise suppression with appropriate parameters, while the resolution enhancement stage can then focus on maximizing resolution improvement without being constrained by noise concerns, effectively resolving the gain-nose tradeoff.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If existing noise reduction methods are applied to reduce noise, then noise is reduced, but edges are deteriorated or residue noise remains

Engineering Contradiction:

Improvenoise reductionVSAvoidedge quality

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies noise reduction as a preliminary step before resolution enhancement, using parameters and methods that are optimized for this specific position in the processing pipeline. By performing noise reduction first, the system can use stronger noise reduction parameters without permanently damaging edges, as the subsequent resolution enhancement process will restore edge sharpness and detail.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a continuous processing pipeline where noise reduction is followed by resolution enhancement. This continuity ensures that the useful action of edge preservation is maintained throughout - the noise reduction step suppresses noise while the immediate follow-up resolution enhancement step restores and sharpens edges, preventing permanent edge deterioration or residue noise that would occur with standalone noise reduction methods.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS10217193B2Image processing apparatus, image capturing apparatus, and storage medium that stores image processing program

Publication Date: 2019.02.26 CANON KK

AI summary

An image processing apparatus generates a first image by performing a resolution enhancement process for the input image, and a second image by performing a noise reduction process for a noise reduction target image. In the noise reduction process, the image processing apparatus extracts a first partial image containing a target pixel and a plurality of second partial images containing a reference pixel, calculates a correlation value between the first partial image and the plurality of second partial images, provides a weight to each of the plurality of second partial images based on a characteristic of the resolution enhancement process and the correlation value, calculates a pixel value of the target pixel using a pixel value of the reference pixel in the plurality of second partial images and the weight, and generate the second image using the calculated pixel value.