Defective Pixel Correction Circuit Memory Segmentation
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Solution Overview
Problem
As television standards evolve to higher resolutions like 4k2k and 8k4k, the number of defective pixels in CMOS sensors increases, exceeding the limited memory capacity for storing correction data, leading to incomplete correction of low-level defective pixels.
Innovation Solution
An image processing apparatus and method that includes a memory storing addresses of defective pixels with specific conditions, such as adjacency to other defective pixels of the same or different color filters, and a correction circuit that adjusts pixel data based on surrounding pixel values, effectively correcting more defective pixels within the memory constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory capacity is increased to store all defective pixel data, then all defective pixels can be corrected, but device cost and complexity increase
Solution Approach 1:
The patent applies local quality by differentiating defective pixels based on their spatial distribution characteristics. Defective pixels are categorized into two groups: those adjacent to same-color defective pixels (stored in first memory region) and those adjacent to different-color defective pixels (stored in second memory region). This localized differentiation allows efficient memory utilization while maintaining correction completeness for all defective pixels.
Solution Approach 2:
The patent segments the memory into two distinct regions: a first memory region for storing defective pixel information adjacent to same-color defective pixels, and a second memory region for storing defective pixel information adjacent to different-color defective pixels. This segmentation strategy optimizes memory usage by organizing defective pixel data according to their spatial and color relationships, enabling complete correction without requiring excessive memory capacity.
2Reliability
If only high-level defective pixels are corrected, then correction accuracy is maintained, but the number of correctable defective pixels is limited
Solution Approach 1:
The patent changes the selection parameter from solely defect level to a combination of spatial relationship and defect level. By storing defective pixel information based on adjacency relationships (same-color or different-color) in addition to defect level, the system expands the number of correctable pixels while maintaining accuracy through the structured memory organization and correction circuit design.
3Reliability
If all defective pixel data is stored in memory, then complete correction is achieved, but memory usage exceeds available capacity
Solution Approach 1:
The patent applies local quality by differentiating defective pixels based on their spatial distribution characteristics. Defective pixels are categorized into two groups: those adjacent to same-color defective pixels (stored in first memory region) and those adjacent to different-color defective pixels (stored in second memory region). This localized differentiation allows efficient memory utilization while maintaining correction completeness for all defective pixels.
Solution Approach 2:
The patent segments the memory into two distinct regions: a first memory region for storing defective pixel information adjacent to same-color defective pixels, and a second memory region for storing defective pixel information adjacent to different-color defective pixels. This segmentation strategy optimizes memory usage by organizing defective pixel data according to their spatial and color relationships, enabling complete correction without requiring excessive memory capacity.
Data Source
AI summary
An image processing apparatus comprises: a memory which stores an address of a defective pixel that satisfies a predetermined condition, among defective pixels included in an image sensor covered with color filters; and a correction circuit which corrects, among pixel data of an image obtained by exposing the image sensor, the pixel data of the defective pixel at the address stored in the memory. The defective pixel is a pixel having pixel data whose difference from a value determined using the pixel data of surrounding pixels is greater than a threshold value, and the predetermined condition includes at least one of a condition that a plurality of defective pixels among pixels corresponding to different or the same color filters are adjacent to each other.