Image Sensor Pixel Readout Order Control for Fixed Pattern Noise Reduction
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Solution Overview
Problem
Image sensing devices, particularly CMOS image sensors, face challenges in reducing fixed pattern noise caused by pixel offsets, which affect image quality.
Innovation Solution
The implementation of a controller that alters the readout order and initialization order of pixel groups between frames, utilizing a shared structure among pixels, including photo diodes, transmission units, initialization units, and selection units, to diffuse fixed pattern noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed readout order is used for pixels in each frame, then the device complexity is reduced and operation is simplified, but fixed pattern noise occurs due to pixel offsets affecting image quality
Solution Approach 1:
The patent applies the dynamics principle by making the readout order variable rather than fixed. The controller dynamically changes the readout sequence of pixels between different frames, specifically alternating between first and second readout orders. This dynamic adjustment allows the system to diffuse fixed pattern noise while managing complexity through predefined patterns rather than arbitrary changes.
Solution Approach 2:
The patent implements periodic action by establishing a repeating pattern of readout orders. The controller alternates between a first readout order and a second readout order in a periodic manner across successive frames. This periodic variation systematically diffuses fixed pattern noise associated with pixel offsets while maintaining a predictable, manageable control structure.
2Measurement precision
If the readout order of pixels is changed between frames, then fixed pattern noise is diffused and image quality is improved, but the device complexity and control difficulty increase
Solution Approach 1:
The controller dynamically adjusts the readout order between frames to diffuse fixed pattern noise. By implementing two specific readout orders (first and second orders) that are alternated periodically, the system achieves variable sequencing without requiring complex arbitrary patterns, thus improving image quality while keeping control manageable.
Solution Approach 2:
The patent uses periodic action by establishing a repeating pattern where the controller alternates between first and second readout orders across successive frames. This systematic periodic variation effectively diffuses fixed pattern noise while maintaining predictable control behavior, reducing the difficulty of managing the changed readout sequences.
3Ease of manufacture
If pixels are read out in a fixed sequence, then the manufacturing and operation are simpler, but pixel offsets cause fixed pattern noise that degrades image quality
Solution Approach 1:
The patent applies dynamics by transitioning from a static, fixed readout sequence to a dynamic system that alternates between two predefined readout orders. This dynamic approach diffuses fixed pattern noise caused by pixel offsets while maintaining ease of manufacture because the two readout orders are systematically defined rather than requiring complex variable sequencing logic.
Solution Approach 2:
The controller implements periodic action by alternating between first and second readout orders in a regular pattern across frames. This periodic variation effectively mitigates fixed pattern noise while preserving manufacturing simplicity, as the alternating pattern is easily implemented through predefined control logic rather than requiring complex manufacturing modifications.
Data Source
AI summary
An image sensing device includes a plurality of pixel groups, each pixel group including two or more neighboring pixels, and a controller suitable for controlling the pixel groups on a basis of a frame unit, wherein a readout order of the pixels in each of the pixel groups is different between present and next frames.