Defective Pixel Correction Using Chromaticity-Weighted Direction Determination
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Solution Overview
Problem
Conventional image processing methods for defective pixels in image sensors are prone to errors due to noise in signal values from peripheral pixels, leading to reduced accuracy in direction determination and pixel correction.
Innovation Solution
An image processing apparatus that determines the degree of achromatic color for a pixel of interest, uses signal values from both same-color and different-color peripheral pixels to determine correlated directions, and performs weighted addition of correction values based on the chromaticity of the pixel to improve accuracy in generating a final signal value for defective pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direction determination is performed using only signal values of eight peripheral pixels surrounding the pixel of interest, then the processing is simple and fast, but the accuracy of direction determination is reduced due to noise influence
Solution Approach 1:
The patent segments the direction determination process into two independent stages: first determining the type of color (achromatic or chromatic) using a broader set of peripheral pixels, then performing direction determination based on this classification. This segmentation allows the system to use more pixels for initial classification while maintaining simpler, faster processing for the actual direction determination step.
Solution Approach 2:
The patent performs preliminary color type determination using signal values from peripheral pixels before conducting the main direction determination. This preliminary action classifies pixels as achromatic or chromatic, which then guides the subsequent direction determination process, allowing for more accurate results without increasing the complexity of the main processing step.
2Reliability
If pixel correction is performed using conventional methods with limited peripheral pixels, then the processing speed is maintained, but the reliability of pixel correction is reduced due to noise errors
Solution Approach 1:
The patent applies local quality by treating achromatic and chromatic pixels differently in the correction process. Achromatic pixels use one set of peripheral pixels for correction, while chromatic pixels use another set, allowing each type to receive optimized correction based on its specific characteristics and noise patterns, thereby improving overall reliability without significantly impacting processing speed.
Solution Approach 2:
The patent changes the parameters used in pixel correction based on the color type determination. By classifying peripheral pixels as achromatic or chromatic and selecting different correction parameters for each type, the system improves correction reliability while maintaining processing efficiency through targeted parameter application rather than uniform processing.
3Measurement precision
If the weight of achromatic color correction value is increased and chromatic color correction value is decreased, then the processing complexity is reduced, but the measurement precision of color accuracy is reduced
Solution Approach 1:
The patent implements dynamic weight assignment where the weights for achromatic and chromatic color correction values are not fixed but are determined based on the specific characteristics of the pixel being corrected. This dynamic approach allows the system to optimize color accuracy by adjusting weights according to the actual image content and noise conditions, while the complexity remains manageable through automated weight determination.
Data Source
AI summary
A direction in which pixels highly correlated with a signal value of a pixel of interest exist is determined by using both signal values of a plurality of pixels of different colors from the pixel of interest and of a plurality of pixels of the same color as the pixel of interest among a plurality of peripheral pixels of the pixel of interest, and obtains pixel correction values corresponding to the respective directions. Weighted addition of those pixel correction values is performed in accordance with the degree to which the pixel of interest is of an achromatic color, and the pixel correction value for the pixel of interest is thus obtained.