Pixel Interpolation Unit Adjusting Frequency Ratios for Low Light Imaging
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Solution Overview
Problem
Conventional single-plate imaging apparatuses face challenges in maintaining high signal-to-noise ratio (S/N) and resolution, especially under low illumination, due to the degradation caused by high-frequency components during image processing, which can lead to noise and resolution issues when converting image signals from RGB to YUV format.
Innovation Solution
An image processing apparatus that includes a pixel interpolation processing unit, which adjusts the ratio of high-frequency and low-frequency components using an analog gain (AG) coefficient to suppress S/N degradation, by multiplying the high-frequency component with the AG coefficient and adding it to the low-frequency component for generating sensitivity level values of lacking color components, thereby reducing the impact of high-frequency components on image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-frequency component is added to suppress resolution degradation, then resolution is improved, but S/N ratio deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the coefficient (alpha) that controls the mixing ratio between high-frequency and low-frequency components based on illumination conditions. Under low illumination, the coefficient reduces the high-frequency component contribution to maintain S/N ratio, while under high illumination, it increases the high-frequency component contribution to maintain resolution. This adaptive parameter adjustment resolves the contradiction between resolution and S/N ratio.
2Manufacturing precision
If high-frequency component is added during interpolation, then resolution is maintained, but color noise is degraded in YUV conversion
Solution Approach 1:
The patent uses parameter changes by controlling the coefficient (alpha) to adjust the high-frequency component ratio before YUV conversion. By reducing this coefficient under conditions where color noise is problematic, the high-frequency component that causes color noise degradation is suppressed, while resolution is maintained through the low-frequency component. This resolves the contradiction between maintaining resolution and preventing color noise.
3Device complexity
If conventional interpolation processing is used, then processing simplicity is maintained, but image quality degrades under low illumination
Solution Approach 1:
The patent applies parameter changes by introducing an illumination-condition-dependent coefficient (alpha) that modulates the contribution of high-frequency components in the interpolation formula. This adds minimal complexity (a single coefficient adjustment) to the conventional interpolation process, enabling significant image quality improvement under low illumination conditions while maintaining processing simplicity through the use of a straightforward coefficient-based modification.
Data Source
AI summary
According to the Embodiments, an Image Processing apparatus includes a pixel interpolation processing unit. The pixel interpolation processing unit generates a sensitivity level value through addition of a first frequency range component of an image signal for a lacking color component and a second frequency range component of a frequency band lower than the first frequency range component. The pixel interpolation processing unit adjusts a ratio of the first frequency range component to be added to the second frequency range component.