Adaptive Image Filtering via Integrated Spatial-Photometric Weighting

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Solution Overview

Problem

Bilateral filters in existing image processing methods fail to effectively remove noise along edges and color boundaries due to separate handling of spatial distance and pixel value difference weighting coefficients, leading to uncorrected noise and artifacts.

Innovation Solution

An image processing method that determines a single integrated weighting coefficient based on the product of spatial distance and signal intensity differences, using this coefficient to filter image data and ensure accurate noise removal without damaging the image structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If separate weighting coefficients are used for spatial distance and pixel value difference in bilateral filters, then the filtering process is simpler and faster, but noise and color artifacts remain uncorrected along edges and color boundaries

Engineering Contradiction:
Improvefiltering speedVSAvoidnoise removal accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent merges the separate spatial weighting coefficient and photometric weighting coefficient into a single integrated weighting coefficient. This coefficient simultaneously considers both spatial distance and signal intensity differences, allowing the filter to effectively remove noise while preserving edges and color boundaries. The integration resolves the contradiction by combining the simplicity of separate coefficients with the accuracy of joint consideration.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If a single integrated weighting coefficient is used based on product of spatial distance and signal intensity difference, then noise removal accuracy improves, but the computational complexity increases

Engineering Contradiction:
Improvenoise removal accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a standardized form for the integrated weighting coefficient that incorporates both spatial and photometric parameters. By defining the coefficient as a product of normalized spatial distance and signal intensity difference, the patent achieves accurate noise removal while maintaining computational efficiency through parameter standardization and pre-computation of distance transforms.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If separate weighting coefficients are handled independently, then the filter structure is simpler, but edges and color boundaries are not properly preserved

Engineering Contradiction:
Improvefilter structure simplicityVSAvoidedge preservation accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent combines spatial and photometric weighting into a single coefficient that is applied uniformly across the filtering operation. This merging ensures that both spatial location and intensity differences are considered together when determining pixel weights, thereby preserving edges and color boundaries effectively while maintaining a relatively simple filter structure.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentUS7945111B2Image processing method for adaptively filtering image data
Publication Date: 2011.05.17 NIKON CORP
  • US7945111B2 patent drawing
  • US7945111B2 patent drawing
  • US7945111B2 patent drawing

AI summary

An image processing method for filtering image data, which is constituted with a plurality of pixels, at each pixel position by using pixel values indicated by pixels present within a predetermined range containing a target pixel, includes: determining two arguments that are a first argument defined by a spatial distance from the target pixel and a second argument defined by a difference in signal intensity relative to the target pixel, in correspondence to each of the pixels present within the predetermined range; obtaining a weighting coefficient to be used when filtering each of the pixels present within the predetermined range, based upon a single integrated argument represented by a product of the first argument and the second argument; and filtering the image data by using a filter coefficient corresponding to the weighting coefficient having been obtained.