Imaging Apparatus Defective Pixel Detection and Correction
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Solution Overview
Problem
Existing imaging devices struggle to accurately detect and correct defective pixels that occur after the shipment of imaging apparatuses, as existing methods are either costly due to memory requirements or suffer from decreased detection and correction performance in certain image areas, such as flat areas, and can incorrectly identify edges as defective pixels.
Innovation Solution
An imaging apparatus and method that analyzes output signals from imaging devices by comparing pixel values within local areas to detect defective pixels based on variations and standard deviations, using a signal processing unit to correct pixel values by referencing intermediate pixel values, and employing a microlens or optical low-pass filter to diffuse light across multiple pixels for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If address data of defective pixels is stored in nonvolatile memory for correction, then defective pixel correction is effective, but apparatus cost increases and the number of correctable pixels is limited by memory capacity
Solution Approach 1:
The patent extracts only the essential defect information (defective pixel coordinates and correction values) and stores it in a compact format in nonvolatile memory, removing unnecessary data storage requirements while maintaining correction capability
Solution Approach 2:
The patent creates a simplified copy of defect data in nonvolatile memory that contains only the essential information needed for correction, rather than storing complete pixel data or large correction tables
2Measurement precision
If standard defective pixel detection methods are used, then manufacturing stage defects are detected, but post-shipment defective pixels occurring due to aging cannot be detected
Solution Approach 1:
The patent implements a dynamic defect detection system that can identify defective pixels at any stage (manufacturing or post-shipment) by continuously monitoring pixel output signals and comparing them against reference values, allowing the system to adapt to aging-related defects
Solution Approach 2:
The patent establishes a feedback mechanism where pixel output signals are continuously monitored and compared against reference values, and when defects are detected, correction values are generated and stored back in nonvolatile memory for ongoing correction
3Measurement precision
If edge areas are analyzed for defective pixel detection, then detection coverage is improved, but edges may be incorrectly identified as defective pixels
Solution Approach 1:
The patent applies different detection thresholds and analysis methods for different image regions, with special handling for edge areas to prevent false positives while maintaining detection sensitivity in normal regions
Solution Approach 2:
The patent adjusts detection parameters (such as threshold values and reference comparison criteria) based on the local characteristics of different image regions, including edge areas, to maintain accurate defect detection without false positives
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables highly accurate detection and correction of defective pixels, resulting in high-quality images with improved detection accuracy and reduced costs by avoiding the need for extensive memory storage and minimizing errors in edge detection.
Implementation Method 1
employing a microlens or optical low-pass filter to diffuse light across multiple pixels for accurate detection
Data Source
AI summary
A defective pixel of an imaging device is detected. An output pixel value of the defective pixel is corrected to generate an output image. An imaging device, and a signal processing unit for analyzing an output signal from the imaging device and detecting a defective pixel are included. The imaging device receives incident light via, for example, a microlens placed in front of a pixel, inputs the same subject light on a local area basis including a plurality of pixels of the imaging device, and acquires an image signal lower than a pixel resolving power corresponding to the pixel density of the imaging device. The signal processing unit compares the pixel values of the same color pixels included in a local area on a local area basis including a cluster of the plurality of pixels of the imaging device, detects the defective pixel based on the comparison result, and corrects and outputs a pixel value of a pixel determined to be a defective pixel.