Image Sensor Photosensitivity Compensation via Uniform Parameter Adjustment
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Solution Overview
Problem
Image sensors face challenges in compensating for differences in photosensitivity among color filters, leading to noise deterioration in signal-to-noise ratio (SNR) due to varying exposure times and gains for red, green, and blue color filters.
Innovation Solution
An image sensing system that includes a sensing controller to adjust exposure time, conversion gain, and analog gain for each color filter set based on calculated sensing parameters, using a parameter addition circuit and sensing parameter calculator to optimize pixel value distribution and compensate for photosensitivity differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different exposure times and gains are used for different color filters, then photosensitivity differences are compensated, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent changes the parameter of photosensitivity compensation from individual color filter level to overall image level. Instead of applying different exposure times and gains to R, G, and B color filters separately, the system calculates a single compensation value based on the standard deviation of pixel values across all color filters and applies it uniformly to all pixels. This parameter change resolves the contradiction by achieving photosensitivity compensation without the need for color-specific adjustments that degrade signal-to-noise ratio.
2Object-affected harmful factors
If uniform exposure time and gain are applied to all color filters, then signal-to-noise ratio is maintained, but photosensitivity differences cannot be compensated
Solution Approach 1:
The patent transforms the compensation approach by changing from multiple color-specific parameters to a single overall compensation parameter. The system calculates pixel value standard deviations for each color filter, determines an appropriate compensation value based on these statistics, and applies it uniformly across all pixels. This maintains uniform exposure and gain settings while still achieving photosensitivity compensation through the overall adjustment.
3Measurement precision
If color-specific sensing parameters are used, then photosensitivity is compensated, but device complexity increases
Solution Approach 1:
The patent merges the compensation control for different color filters into a single unified control mechanism. Instead of independently controlling exposure time, conversion gain, and analog gain for each color filter (R, G, B), the system calculates a single compensation value and applies it uniformly to all color filters. This merging reduces device complexity by eliminating the need for multiple color-specific parameter control paths while maintaining effective photosensitivity compensation.
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
The system effectively reduces noise in image data by adjusting sensing parameters for each color filter, improving the signal-to-noise ratio and enhancing image quality by compensating for photosensitivity variations.
Implementation Method 1
each unit pixel configured to convert an optical signal of an object into a pixel signal
Data Source
AI summary
An image sensing system includes an image sensor, a sensing controller, an additional unit, and a sensing parameter calculator. The image sensor includes a plurality of unit pixels and configured to generate raw image data indicative an image of an object from pixel signals from the plurality of unit pixels. The sensing controller is configured to control, based on a sensing parameter, a sensing condition of the image sensor for each set of the unit pixels. The parameter addition circuit is configured to obtain a parameter added data by adding the sensing parameter and the raw image data. The sensing parameter calculator is configured to calculate a distribution of pixel values for each set of the unit pixels, calculate an updated sensing parameter based on the distribution of pixel values, and transmit the updated sensing parameter to the sensing controller and the parameter addition circuit.