Solid-State Imaging Device Signal Processing for High Dynamic Range
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in maintaining linearity of output voltages for signals with different dynamic ranges, leading to variations among individual units and pixels, resulting in noise and image deterioration such as tone jumps and false colors.
Innovation Solution
A solid-state imaging device that combines read-out signals by selecting necessary signals based on comparisons with threshold values and referencing combinational information from surrounding pixels, ensuring equal inclinations and smooth switching, thereby generating a high dynamic range signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If signals with different dynamic ranges are combined by digital correction based on center value parameters, then the dynamic range is extended, but linearity variations occur due to individual unit and pixel variations, resulting in tone jumps and image deterioration
Solution Approach 1:
The patent changes the parameter used for signal combination from fixed center value parameters to actual threshold values measured for each pixel. By using pixel-specific threshold values that reflect individual variations, the system maintains linearity across different dynamic range signals while still achieving extended dynamic range through combination. This parameter change from generic to specific values resolves the contradiction between adaptability and manufacturing precision.
2Measurement precision
If threshold values are corrected digitally after ADC conversion, then signal linearity is maintained, but individual variations among pixels cannot be compensated, leading to discontinuous points and noise
Solution Approach 1:
The patent implements feedback by measuring the actual threshold value for each pixel and using that measured value in the signal combination process. This feedback loop ensures that the combination threshold reflects the true characteristics of each pixel, enabling smooth switching between different dynamic range signals without discontinuous points or noise, thereby improving reliability while maintaining measurement precision.
3Adaptability or versatility
If multiple signals are combined to extend dynamic range, then higher luminance and low luminance coverage is improved, but false colors and image deterioration occur due to linearity mismatches
Solution Approach 1:
The patent applies local quality by using individualized threshold values for each pixel rather than a uniform threshold for all pixels. This allows each pixel to contribute its signal with the correct linearity characteristics to the combined output, preventing false colors and image deterioration while maintaining comprehensive luminance coverage from high to low luminance levels.
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 allows for smooth signal combination, suppressing noise and image deterioration, and achieving higher image quality with extended dynamic range.
Implementation Method 1
photoelectric conversion elements detecting light and generating a charge
Data Source
AI summary
A solid-state imaging device 10 includes a signal processing part 710 which, when combining specific read-out signals among the plurality of read-out signals, selects at least one signal which becomes necessary for a combinational operation in accordance with a result of a comparison between at least one read-out signal among the plurality of read-out signals and a threshold value, applies the selected signal to the combinational processing, and generates a combined signal extended in dynamic range, and wherein the signal processing part, when combining read-out signals from one specific pixel, determines the combinational information concerning the combinational operation of these read-out signals with reference to the combinational information concerning the combinational operation of the surrounding pixels of the one specific pixel. By this configuration, it is possible to smoothly switch a plurality of signals, possible to realize a higher dynamic range and a higher quality of image.