Adaptive Color Interpolation for Bayer CFA Sharpness

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Solution Overview

Problem

Current digital image processing devices face challenges in color interpolation, particularly in restoring the green channel from red and blue channels in Bayer CFA systems, as different methods for calculating interpolation candidates and weights have advantages and disadvantages, leading to uncertainty in method selection.

Innovation Solution

A device and method for color interpolation that adaptively use multiple methods for calculating interpolation candidates and weights based on local gradient similarity and complexity, incorporating processors to calculate third-direction interpolation values and weights, and applying these to interpolate G values in the red or blue channels of a Bayer color filter array.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single interpolation method is used for calculating interpolation candidates and weights, then the device complexity is reduced, but the interpolation quality (sharpness and edge noise minimization) deteriorates

Engineering Contradiction:
Improveinterpolation method complexityVSAvoidinterpolation quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the interpolation method adaptive rather than fixed. The system dynamically selects between different interpolation methods (e.g., gradient-based, variance-based, edge-directed) for calculating interpolation candidates and weights based on local image characteristics such as edge detection results and texture complexity. This allows the interpolation quality to be optimized for different regions of the image while managing device complexity through algorithmic adaptation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements local quality by applying different interpolation methods to different regions of the image based on local characteristics. For example, edge-directed interpolation is applied in edge regions to preserve sharpness, while smooth-region interpolation is used in flat areas to minimize noise. The system calculates local metrics such as gradient magnitude, variance, and edge orientation to determine the appropriate interpolation method for each pixel neighborhood, thereby optimizing interpolation quality locally without uniformly increasing device complexity.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If multiple interpolation methods are used for calculating interpolation candidates and weights, then the interpolation quality is improved, but the device complexity increases

Engineering Contradiction:
Improveinterpolation qualityVSAvoidinterpolation method complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system dynamically selects and switches between multiple interpolation methods based on real-time analysis of local image characteristics. Rather than implementing all methods simultaneously with full complexity, the system evaluates local metrics (edge strength, texture complexity, gradient direction) and activates only the most suitable interpolation method for each region, thereby improving interpolation quality while managing device complexity through conditional execution.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Different interpolation methods are applied to different local regions of the image based on their specific characteristics. Edge regions use edge-directed interpolation to maintain sharpness, flat regions use simple averaging to minimize noise, and texture regions use variance-based methods to preserve detail. This localized application of multiple methods improves overall interpolation quality while reducing the effective complexity by not applying all methods uniformly across the entire image.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If adaptive interpolation is applied based on local gradient similarity and complexity, then edge noise is minimized and sharpness is improved, but the calculation time and processing complexity increase

Engineering Contradiction:
Improveedge noise minimization and sharpnessVSAvoidcalculation time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs preliminary analysis of local image characteristics such as gradient similarity, edge detection, and complexity metrics before executing the interpolation process. By pre-calculating these metrics and determining the appropriate interpolation method for each region in advance, the system avoids redundant calculations during the actual interpolation phase, thereby improving edge noise minimization and sharpness while reducing overall calculation time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The adaptive interpolation process focuses computational resources on regions that require it most. By analyzing local gradient similarity and complexity, the system identifies edge regions that need careful handling to minimize noise and preserve sharpness, while applying simpler, faster interpolation methods in flat regions. This localized adaptive approach improves quality where needed without uniformly increasing calculation time across the entire image.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS11263724B2Device for interpolating colors and method thereof
Publication Date: 2022.03.01 HANWHA VISION CO LTD
  • US11263724B2 patent drawing
  • US11263724B2 patent drawing
  • US11263724B2 patent drawing

AI summary

A device for interpolating a color includes at least one processor to implement: a directions interpolation candidate values calculator configured to calculate third horizontal/vertical directions interpolation candidate values with respect to a pixel in a red (R) channel or a blue (B) channel on a Bayer color filter array pattern, based on a local gradient similarity between the R channel and a green (G) channel or a local gradient similarity between the B channel and the G channel; a directions interpolation weights calculator configured to calculate third horizontal/vertical directions interpolation weights based on the first horizontal/vertical directions interpolation candidate values by using a local complexity; and a G value interpolation execution unit configured to interpolate a G value of the pixel in the R channel or the B channel based on the calculated third horizontal/vertical directions interpolation candidate values and the third calculated horizontal/vertical directions interpolation weights.