Solid-State Imaging Signal Processing Circuit for High Gradability
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Solution Overview
Problem
Existing signal processing technologies for solid-state imaging elements struggle to display original luminance information with high gradability while achieving a wide dynamic range, often resulting in unnatural gradation due to differences in charge accumulation time and photosensitivity between pixels.
Innovation Solution
A signal processing circuit that includes a first pixel group with short charge accumulation time or low photosensitivity and a second pixel group with longer accumulation time or higher photosensitivity, where the signal value of the first pixel group is multiplied and weighted based on the signal value of a peripheral pixel to alleviate stepwise variance, allowing for the synthesis of signal values from both groups to represent original luminance information with high gradability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If signal values from pixels with different charge accumulation times are synthesized by simple weighting, then dynamic range is expanded, but unnatural gradation with stepwise variance occurs
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the weighting coefficient based on the signal values of surrounding pixels. Instead of using fixed weighting, the system changes the weighting parameter adaptively to compensate for the stepwise variance caused by different charge accumulation times, thereby maintaining natural gradation while expanding dynamic range
Solution Approach 2:
The patent implements feedback by using the signal values of surrounding pixels to determine the weighting coefficient for synthesis. The system continuously monitors the local image characteristics and adjusts the weighting accordingly, creating a closed-loop control that prevents unnatural gradation artifacts
2Productivity
If the number of bits for signal processing is reduced, then processing efficiency is improved, but original luminance information with high gradability is lost
Solution Approach 1:
The patent introduces an intermediary weighting coefficient that acts as a mediator between the synthesized signal and the final output. This intermediary element allows the system to preserve luminance information with high gradability by carefully controlling how signals from different exposure times are combined, preventing information loss while maintaining processing efficiency
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 effectively reduces unnatural gradation and enhances the representation of original luminance information, enabling higher gradability and more accurate image reproduction by adjusting signal values based on the differences in accumulation time and photosensitivity between pixel groups.
Implementation Method 1
an output signal which is almost linear with respect to the amount of charge accumulated by photoelectric conversion may be obtained from a unit pixel
Data Source
AI summary
A signal processing circuit of a solid-state imaging element which processes a signal of the solid-state imaging element having a first pixel group and a second pixel group in which a charge accumulation time or photosensitivity is different by α times from that of the first pixel group, includes a calculation unit that multiplies a signal value of a pixel of interest in the first pixel group by α times, a weighting unit that performs weighting with respect to the signal value of the pixel of interest based on a signal value of a pixel associated with the pixel of interest, and a synthesis unit that synthesizes the signal value which has been multiplied by α times in the calculation unit and on which the weighting has been performed in the weighting unit and a signal value of a pixel of the second pixel group.