Pixel Value Calibration for Green Color Non-Uniformity in Bayer Sensors
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Solution Overview
Problem
Existing image calibration methods fail to effectively address green color non-uniformity in images captured by single sensors using Bayer Color Filter Arrays, leading to fidelity loss and visible artifacts like maze patterns and color tints, while also increasing costs due to the need for additional calibration units and buffer memories.
Innovation Solution
A pixel value calibration device and method that includes an edge detecting unit, a weighted value estimating unit, a calibration value generating unit, and a calibrating unit to generate calibrated pixel values by analyzing edge detection values and weighted values associated with candidate pixels, effectively addressing green color non-uniformity without blurring image texture or edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an independent calibration unit is used to address green color non-uniformity, then calibration effectiveness is improved, but device complexity and cost increase due to additional buffer memories and communication units
Solution Approach 1:
The patent merges the green color non-uniformity calibration function with the existing interpolation processing unit, eliminating the need for a separate independent calibration unit. The calibration unit shares the same processing resource with the interpolation unit, thereby reducing device complexity and cost while maintaining calibration effectiveness through integrated processing.
2Reliability
If an independent calibration unit is used to address green color non-uniformity, then calibration effectiveness is improved, but manufacturing cost increases due to extra buffer memories
Solution Approach 1:
The patent combines the calibration functionality with the existing interpolation processing unit, eliminating the need for separate buffer memories dedicated to the calibration unit. This integration reduces the total memory requirement and simplifies the manufacturing process, thereby reducing manufacturing cost while preserving calibration effectiveness.
3Productivity
If green color non-uniformity calibration is performed without proper edge detection, then calibration speed is improved, but image quality deteriorates due to blurred texture and lost high-frequency information
Solution Approach 1:
The patent performs edge detection as a preliminary action before the calibration process. By detecting edges and identifying regions that should not be calibrated (such as texture areas and object boundaries) in advance, the system can selectively apply calibration only to appropriate regions. This preliminary edge detection enables faster calibration of valid regions while preserving image quality and high-frequency information in texture and edge areas.
4Device complexity
If conventional calibration methods are used, then processing simplicity is maintained, but fidelity loss occurs due to inability to distinguish green color non-uniformity from image texture
Solution Approach 1:
The patent performs preliminary edge detection to identify regions that should be excluded from calibration (such as texture areas and object boundaries). This preliminary action enables the system to distinguish between green color non-uniformity in smooth regions and legitimate image texture, thereby preventing fidelity loss while maintaining relatively simple processing through the use of edge detection masks.
Solution Approach 2:
The patent applies different processing qualities to different regions of the image based on edge detection results. Regions identified as smooth areas undergo full calibration processing to correct green color non-uniformity, while regions identified as texture areas or object boundaries are excluded from calibration to preserve their original characteristics. This local differentiation maintains fidelity by applying calibration only where appropriate.
Data Source
AI summary
A pixel value calibration device comprises: an edge detecting unit to generate edge values according to the target pixel value of a target pixel and the pixel values of neighboring pixels in which the target and neighboring pixels are of a first color and each of them is arranged with pixels of a second color in the same pixel row; a weighted value estimating unit to generate weighted values according to the edge values and an algorithm in which the weighted values are associated with candidate pixels each of which is arranged with pixels of a third color in the same pixel row; a calibration value generating unit to generate a calibration value according to the target pixel value and the pixel value(s) of the candidate pixel(s) plus the weighted value(s) thereof; and a calibrating unit to generate a calibrated pixel value according to the target pixel and calibration values.