Color Filter Array Interpolation Using Local Edge Gradients

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Solution Overview

Problem

Existing methods for interpolating missing colors in color filter arrays suffer from image quality degradation due to sub-optimal interpolation directions and the introduction of artifacts, often requiring complex and costly processing.

Innovation Solution

A method that determines interpolation directions for each red and blue photosite based on local edge information, interpolating green colors for red and blue photosites, and vice versa, using directional gradients to select the most likely edge direction for accurate interpolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional interpolation methods are used to fill missing colors in CFA, then the de-mosaicing process can be completed, but image quality degrades due to sub-optimal interpolation directions and artifacts

Engineering Contradiction:
Improveinterpolation accuracyVSAvoidimage artifacts
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by determining interpolation directions based on local edge information for each red and blue photosite. Instead of using a uniform interpolation approach across the entire image, the method analyzes local gradient information around each photosite to identify the predominant edge direction, then performs interpolation along that specific direction. This localized adaptation to local image characteristics reduces artifacts and improves interpolation accuracy.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by making the interpolation direction adaptive rather than fixed. The method dynamically determines the interpolation direction for each photosite based on local gradient calculations, allowing the interpolation strategy to adapt to varying edge orientations throughout the image. This dynamic adjustment of interpolation parameters according to local image content reduces artifacts caused by static, one-size-fits-all interpolation methods.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If complex processing methods are employed to improve interpolation accuracy, then image quality may improve, but processing complexity and cost increase

Engineering Contradiction:
Improveinterpolation accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the interpolation process into distinct stages: first determining edge directions through gradient analysis, then performing interpolation along identified directions, and finally processing different color channels (green for red/blue photosites, red/blue for green photosites) separately. This segmented approach breaks down the complex de-mosaicing problem into manageable steps, improving accuracy while maintaining reasonable processing complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by first determining the interpolation direction for each red and blue photosite using local gradient information before performing the actual color interpolation. This preliminary step of identifying edge directions allows subsequent interpolation to be performed more accurately along the correct orientation, reducing the need for complex iterative refinement processes and simplifying the overall algorithm.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS7825965B2Method and apparatus for interpolating missing colors in a color filter array
Publication Date: 2010.11.02 ADVANCED INTERCONNECT SYST LTD
  • US7825965B2 patent drawing
  • US7825965B2 patent drawing
  • US7825965B2 patent drawing

AI summary

A method, of interpolating missing colors in a color filter array comprising red, green and blue photosites comprises determining and interpolation direction for each red and each blue photosite based on local edge information and interpolating a green color for each red and each blue photosite in the determined interpolation direction for that photosite. For each green photosite, red and blue colors are interpolated. For each red photosite, a blue color is interpolated in the determined interpolation direction for that photosite and for each blue photosite, a red color is interpolated in the determined interpolation direction for that photosite.