Image Sensor Flicker Detection via Row Timestamp Variation
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Solution Overview
Problem
Digital imaging systems face challenges in accurately detecting and compensating for light source distortion, particularly from artificial illumination sources like incandescent lights, fluorescent lights, and LEDs, which cause flickering and distortions that affect image quality and color balance.
Innovation Solution
The implementation of an image sensor array with a flicker detection mode that samples light from rows of pixels at varying timestamps, using techniques such as Fast-Fourier transforms to identify flicker frequencies and correct for distortions, allowing for improved white balancing and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional image sensors capture images at fixed frame rates, then image capture is simplified, but flicker detection precision deteriorates due to coupling with light source modulation frequencies
Solution Approach 1:
The patent divides the image sensor into multiple independently controllable pixel rows, where odd rows and even rows can be sampled at different timestamps. This segmentation allows the system to collect temporal information at varying intervals without requiring a completely complex sampling architecture, thereby improving flicker detection precision while managing device complexity.
Solution Approach 2:
The patent implements dynamic sampling where the timestamp for sampling different pixel rows varies over time rather than being fixed. By dynamically adjusting the sampling timestamps of different rows, the system can decouple from light source modulation frequencies and improve flicker detection precision without requiring a completely static complex system.
2Loss of information
If multiple pixels are sampled at the same timestamp, then sampling is simplified, but temporal information for flicker detection is insufficient
Solution Approach 1:
The patent segments the pixel array into multiple rows that are sampled at different timestamps. This segmentation ensures that temporal information is preserved across different sampling moments while maintaining efficient batched sampling operations, thereby reducing temporal information loss without significantly sacrificing sampling efficiency.
Solution Approach 2:
The patent employs periodic sampling patterns where different pixel rows are sampled in an alternating sequence (odd rows at one timestamp, even rows at another). This periodic action ensures comprehensive temporal information capture while maintaining regular, efficient sampling operations that do not significantly reduce productivity.
3Measurement precision
If frame rate is increased to capture faster temporal variations, then flicker detection capability is improved, but energy consumption and motion blur increase
Solution Approach 1:
The patent segments the sampling process across multiple pixel rows with different timestamps, allowing the system to detect a wide range of flicker frequencies without requiring a uniformly high frame rate across the entire sensor. This segmentation enables precise flicker detection while maintaining lower overall energy consumption compared to increasing the global frame rate.
Data Source
AI summary
An imaging system includes a plurality of optical sensors arranged on an integrated circuit in an array with a plurality of rows and a plurality of columns, with a plurality of sets of filters configured over the plurality of sensors, with each filter of a set of filters being associated with a corresponding optical sensor of the array of optical sensors to provide a filter/sensor pair and each filter of a set of filters also configured to pass a target wavelength range of light. The system includes an interface communicating with the plurality of optical sensors, memory storing operational instructions and processing circuitry configured to sample an image using the plurality of optical sensors for each filter/sensor pair associated with a same target wavelength of light on a row-by-row basis at a predetermined sampling rate to produce row-by-row sample outputs, where the processing circuitry is further configured to initiate sampling at least some rows of the plurality of rows of optical sensors using different time stamps.