Defect Pixel Correction Using Adjacent Defect Signals
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Solution Overview
Problem
Conventional image pickup apparatuses face challenges in maintaining image quality over time due to defect pixels in solid-state image sensors, which are not effectively addressed by existing defect detection and correction methods, especially when adjacent normal pixels are not present.
Innovation Solution
A defect pixel correction apparatus and method that corrects pixel signals by utilizing the pixel signal of an adjacent defect pixel of a lower order when no normal pixel is present, ensuring continuous image quality by interpolating from nearby defect pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If defect detection is executed at factory shipment and defect information is stored, then defect pixels can be corrected initially, but new defect pixels generated after factory shipment cannot be detected and corrected
Solution Approach 1:
The system performs preliminary defect detection at factory shipment and stores the defect information in advance. This preliminary action establishes a baseline defect map that can be used for correction, while the system is designed to accommodate future updates when new defects are detected during the product lifecycle.
Solution Approach 2:
The system implements a feedback mechanism where defect detection results are continuously updated and stored. The correction unit uses the most recent defect information to correct defect pixels, ensuring that newly generated defect pixels after factory shipment are detected and corrected based on the latest defect data available.
2Measurement precision
If interpolation is executed using only adjacent normal pixels, then correction accuracy is maintained, but correction cannot be performed when no adjacent normal pixels are present
Solution Approach 1:
The system dynamically changes the parameter of pixel selection based on availability. When adjacent normal pixels are present, it uses them for interpolation; when they are not present, it switches to using adjacent defect pixels. This parameter change allows the correction to be applicable in all scenarios while maintaining the best possible accuracy given the available data.
Solution Approach 2:
The system converts the harmful factor of defect pixels into a beneficial resource. Instead of treating defect pixels solely as errors to be avoided, the invention utilizes adjacent defect pixels as valid data sources for interpolation when normal pixels are unavailable. This transforms the problem of defect pixel presence into a solution that enables correction in previously uncorrectable scenarios.
3Reliability
If multiple defect information records are stored for the same pixel position, then comprehensive defect coverage is achieved, but determining which record to use becomes complex
Solution Approach 1:
The system performs preliminary organization of defect information by storing multiple records with temporal or priority markers. This preliminary structuring of data enables efficient retrieval and selection of the most appropriate defect information without requiring complex real-time decision-making logic.
Solution Approach 2:
The system introduces an intermediary selection mechanism that manages multiple defect information records. This intermediary layer (the selection logic) simplifies the complexity by automatically determining which record to use based on predefined criteria such as recency or defect level, shielding the rest of the system from the complexity of multiple records.
Data Source
AI summary
A defect pixel correction apparatus includes an internal memory which associates and stores a position of a defect pixel with an order of the defect pixel in an image sensor and a processor which corrects a pixel signal of an object pixel based on a pixel signal of an adjacent normal pixel when the adjacent normal pixel is present in the neighborhood of the object pixel and corrects the pixel signal of the object pixel based on a pixel signal of an adjacent defect pixel of a lowest order when the adjacent normal pixel is not present and the adjacent defect pixel of a lower order than an order of the object pixel is present.