Image Pickup Apparatus Defective Pixel Detection and Correction
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Solution Overview
Problem
Conventional image pickup apparatuses with shared electrical construction between pixels face issues such as flickering defects and improper detection of defective pixels, leading to degraded image quality, as noise charge affects multiple adjacent pixels and signal correction methods may incorrectly identify healthy pixels as defective.
Innovation Solution
An image pickup apparatus with a storage unit for pre-stored position information of defective pixels, a defective pixel-detecting unit for identifying new defective pixels using various detection processing methods, and a control unit to execute these methods based on the number of defective pixels in each group, allowing for accurate detection and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple pixels share part of electrical construction to increase pixel density, then pixel integration is improved, but defective pixels occur more frequently due to noise charge accumulation
Solution Approach 1:
The patent divides pixels into groups where each group shares a common floating diffusion unit. By segmenting the pixel array into such groups and independently managing defective pixels within each group, the system can detect and correct defective pixels more effectively without affecting the entire array, thus maintaining high pixel density while improving reliability.
Solution Approach 2:
The patent performs preliminary detection and storage of defective pixel positions within each pixel group before actual image capture. By pre-identifying and recording the locations of defective pixels (including those affected by noise charge), the system can apply corrections during image processing, preventing defective pixel artifacts from degrading image quality.
2Ease of operation
If conventional defective pixel detection is used, then detection simplicity is maintained, but adjacent defective pixels are misidentified due to shared electrical construction
Solution Approach 1:
The patent applies different detection and correction strategies to different local regions (pixel groups) based on their specific characteristics. By treating each pixel group as a local unit with its own defective pixel profile, the system accurately identifies defective pixels within each group context, avoiding misidentification caused by shared electrical construction while maintaining operational simplicity.
Solution Approach 2:
The patent implements a feedback mechanism where detected defective pixel positions are stored and used to guide subsequent detection and correction processes. The system continuously refines its understanding of defective pixel locations within each group by comparing detected signals against stored defective pixel information, improving identification accuracy while maintaining a simple operational framework.
3Reliability
If signal correction using adjacent pixels is applied, then image quality improvement is achieved, but healthy pixels may be incorrectly corrected
Solution Approach 1:
The patent performs correction operations locally within each pixel group rather than globally across the entire array. By limiting correction to specific pixel groups and using only non-defective pixels within those groups as reference, the system avoids incorrectly correcting healthy pixels while still improving image quality in regions with defective pixels.
Solution Approach 2:
The patent preliminarily identifies and excludes defective pixels from the correction process by comparing detected pixel signals against stored defective pixel position information. This preliminary filtering ensures that only healthy pixels are used as reference for correction, preventing the miscorrection of healthy pixels while maintaining image quality improvement.
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
Enables effective detection and correction of defective pixels, improving image quality by accounting for the high likelihood of adjacent pixels sharing electrical construction becoming defective, thereby reducing flickering defects and ensuring accurate signal processing.
Implementation Method 1
a plurality of pixel groups arranged two-dimensionally, each pixel group being formed by a plurality of pixels having a pixel structure in which two or more pixels share part of electrical construction therebetween
Data Source
AI summary
An image pickup apparatus which can detect, when pixels have a structure in which part of electrical construction is shared therebetween, a defective pixel by taking into account a high possibility of the other pixels sharing the part of electrical construction becoming defective pixels, thereby making it possible to obtain an excellent image. A ROM stores in advance position information on each defective pixel. A defective pixel-detecting section detects a new defective pixel on which position information is not stored by the storage unit, from the pixels forming each pixel group, by performing one of different types of defective pixel detection processing. A system controller causes the defective pixel-detecting section to execute one of the different types of detection processing, according to the number of defective pixels which are included in each pixel group and on which the position information is stored in the storage unit.