CMOS Image Sensor Noise-Adaptive Pixel Interpolation
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Solution Overview
Problem
Existing imaging devices with RGBW or CMOS image sensors face challenges in accurately interpolating pixel values due to noise signals, leading to false edge detection and reduced image quality.
Innovation Solution
The proposed solution involves a pixel unit with a first pixel surrounded by second pixels that provide more brightness information, a directional property determination unit, a correlation value calculation unit, and an interpolation processing unit. The unit calculates a correlation value based on the second pixels' values and interpolates the first pixel's value when the correlation value exceeds a noise threshold, or uses an average value when the threshold is not met, to avoid false pattern generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If edge direction detection is performed using gradient of pixel values to improve interpolation accuracy, then interpolation precision is improved, but false edge detection occurs due to noise signals
Solution Approach 1:
The patent applies preliminary action by performing noise filtering on the pixel values of second pixels before calculating the gradient and detecting edge direction. This preprocessing step removes noise signals that would otherwise cause false edge detection, ensuring that the subsequent gradient calculation and edge direction determination are based on clean, reliable data. The filtering operation is performed in advance of the main interpolation process, preventing noise from corrupting the edge detection results.
2Measurement precision
If more second pixels are arranged around the first pixel to increase brightness information, then interpolation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by arranging second pixels that provide brightness information specifically around first pixels that require interpolation. Rather than uniformly increasing pixel density across the entire sensor, the design places additional brightness-providing pixels only where needed for interpolation purposes. This localized arrangement improves interpolation accuracy in specific regions while minimizing the overall increase in device complexity and pixel count.
Data Source
AI summary
An imaging device has: a pixel unit including a first pixel and second pixels arranged around the first pixel and adapted to provide more brightness information than is provided by the first pixel; a directional property determination unit that determines a direction of an intensity distribution based on differences of the values of the second pixels; a correlation value calculation unit that calculates a correlation value of the values of the second pixels; and an interpolation processing unit that, when the correlation value is greater than a threshold based on a noise signal intensity in the values of the second pixels, interpolates a value of the first pixel that is based on the direction of the intensity distribution from the values of the second pixels and, otherwise, interpolates the value of the first pixel from the values of the second pixels without depending on the direction of the intensity distribution.