Defective Pixel Correction in Bayer Image Sensors
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Solution Overview
Problem
Existing methods fail to effectively correct defective pixels caused by decayed photodiodes in image sensors, particularly on Bayer images, as they cannot detect these defects in real-time and update the defect map promptly.
Innovation Solution
A system and method that interpolates pixels with red, green, and blue colors, generates chroma signals, filters these signals to detect defective pixels, and uses edge features from neighboring pixels to correct them, allowing for real-time detection and correction in the chroma domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a defect map is used to record defective pixels, then defective pixel correction can be performed, but the defect map becomes outdated and cannot detect newly decayed photodiodes in real-time
Solution Approach 1:
The patent implements a feedback mechanism where the chroma domain defect detection result is fed back to update the defect map in real-time. The defect map is continuously updated with newly detected defective pixels, ensuring that the correction process always uses the most current defect information, thus resolving the time delay issue while maintaining correction reliability.
Solution Approach 2:
The patent performs preliminary defect detection in the chroma domain before final image output, allowing defective pixels to be identified and the defect map to be updated proactively. This preliminary action ensures that subsequent corrections use up-to-date defect information rather than relying on outdated defect maps.
2Productivity
If defective detection is performed on a Bayer image, then real-time detection can be achieved, but the inherent pixel crosstalk effect prevents effective detection of defective pixels
Solution Approach 1:
The patent transforms the defect detection problem from the spatial domain to the chroma domain by converting RGB values to chroma components (CbCr). This dimensional change allows detection of defective pixels based on chroma anomalies rather than spatial patterns, effectively avoiding the pixel crosstalk issue inherent in Bayer images while maintaining real-time detection capability.
Solution Approach 2:
The patent changes the detection parameter from spatial intensity values to chroma domain values. By detecting defective pixels through chroma signal abnormalities rather than direct pixel intensity comparison, the method overcomes the pixel crosstalk effect that plagues Bayer image detection while preserving real-time detection speed.
3Ease of manufacture
If photodiodes are used for light sensing, then image capture can be performed, but process errors cause photodiode decay and create defective pixels
Solution Approach 1:
The patent implements a self-service mechanism where the image processing system automatically detects and corrects defective pixels caused by photodiode decay without requiring manual intervention or hardware replacement. The chroma domain defect detection and automatic correction algorithm allows the system to compensate for photodiode degradation, maintaining reliability while preserving the simplicity of the original sensor design.
Data Source
AI summary
A method and system for correcting defective pixels of a color image, which first performs an interpolation on a Bayer image captured by an image sensor to thus reconstruct red, green and blue (RGB) colors corresponding to each pixel and obtain an RGB image, then converts the RGB image from the RGB domain to a chroma domain, and finally uses neighboring pixel values to correct a respective defective pixel. Because a defective pixel can be distinct from the chroma domain easier than the RGB domain, it can accurately determine whether or not a pixel to be processed is defective.