Pixel Interpolation Using Correlation Direction for Unknown Color Filters
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Solution Overview
Problem
Existing pixel interpolation techniques struggle with unknown color filter array patterns, leading to inadequate interpolation performance and the need for color-dependent processing.
Innovation Solution
A pixel interpolation processing apparatus that calculates correlation values and determines the correlation direction using a surrounding area of pixels, allowing for accurate interpolation without requiring information about the color filter array pattern, by utilizing orthogonal and inclined directions to estimate color component values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixel interpolation is performed using conventional methods that assume known Bayer array patterns, then interpolation can be performed for standard RGB filters, but the method becomes inapplicable and performance deteriorates when the color filter array pattern is unknown
Solution Approach 1:
The patent dynamically determines the correlation direction for each pixel based on local image characteristics rather than assuming a fixed interpolation pattern. The system calculates correlation values in multiple directions (horizontal, vertical, diagonal) and adaptively selects the optimal direction for each pixel, making the interpolation method versatile for unknown color filter patterns while maintaining high accuracy
Solution Approach 2:
The patent changes the approach from using fixed pattern-based interpolation parameters to dynamically calculated correlation parameters. By computing correlation values in different directions and selecting the direction with highest correlation, the system adapts to unknown color filter arrangements while ensuring reliable interpolation results
2Measurement precision
If pixel interpolation uses color-dependent processing based on known array patterns, then interpolation can be optimized for specific filter types, but the device complexity increases and the method cannot handle unknown patterns
Solution Approach 1:
The patent segments the interpolation process into direction-independent correlation calculation and direction-based selection. By dividing the problem into calculating correlations in multiple fixed directions and then selecting the best direction based on calculated values, the system achieves high precision without requiring complex color-dependent processing or knowledge of the specific filter pattern
Solution Approach 2:
The patent creates a universal interpolation method that works for any color filter array pattern by using correlation-based direction selection rather than pattern-specific processing. The same algorithm adapts to different filter configurations (RGB, four-color, unknown patterns) without requiring different processing paths, reducing device complexity while maintaining precision
3Productivity
If pixel interpolation is performed without considering correlation direction, then the processing is simpler, but the interpolation accuracy deteriorates especially at boundaries between gray and color areas
Solution Approach 1:
The patent performs preliminary correlation calculations in multiple directions before executing the final interpolation. By pre-calculating correlation values horizontally, vertically, and diagonally, the system identifies the optimal interpolation direction in advance, ensuring high accuracy at boundaries while maintaining efficient processing through systematic pre-computation
Data Source
AI summary
A pixel interpolation processing apparatus and an image capturing apparatus are provided that are capable of performing a pixel interpolation process properly even when the pattern of color filter array is unknown. An imaging apparatus includes an imaging unit having a single-chip image sensor having four-color filter array for obtaining an image signal, and the imaging apparatus uses pixel data for a surrounding area around a target pixel to calculate a plurality of sets of correlation values in two directions orthogonal to each other, and determines the correlation direction based on these correlation values. The imaging apparatus obtains first to fourth color component pixel values for the target pixel relying on the fact that the high-frequency components of pixel signals in a direction orthogonal to a direction with high correlation have high correlation regardless of the color of color filters, thus allowing for performing pixel interpolation processing properly even if the four colors of color filters are unknown.