Hybrid Linear Logarithmic Pixel Array Signal Processing
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Solution Overview
Problem
Image sensors with both linear and logarithmic pixels face challenges in capturing a wide dynamic range due to saturation issues, where linear pixels clip at high light levels and logarithmic pixels clip at low light levels, leading to degraded image output.
Innovation Solution
A signal processing method that combines linear and logarithmic pixel values using interpolation techniques to generate a combined pixel value, allowing for a wider dynamic range by utilizing linear pixels at low light levels and logarithmic pixels at high light levels, ensuring monotonicity and continuity of the output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear pixels are used in image sensor, then low light level detection is improved, but high light level saturation occurs
Solution Approach 1:
The image sensor array is segmented into two distinct types of pixels: linear pixels for low light level detection and logarithmic pixels for high light level detection. This segmentation allows each pixel type to operate in its optimal range without suffering from the limitations of the other type.
Solution Approach 2:
Different regions of the pixel array are assigned different pixel types based on local lighting conditions. Linear pixels with higher quantum efficiency are positioned where low light detection is critical, while logarithmic pixels with saturation resistance are positioned for high light level areas, optimizing local performance throughout the array.
2Measurement precision
If logarithmic pixels are used in image sensor, then high light level detection is improved, but low light level detection deteriorates
Solution Approach 1:
The image sensor array is segmented into two distinct types of pixels: linear pixels for low light level detection and logarithmic pixels for high light level detection. This segmentation allows each pixel type to operate in its optimal range without suffering from the limitations of the other type.
3Adaptability or versatility
If both linear and logarithmic pixels are combined in single array, then dynamic range is expanded, but image quality degrades due to saturation in both pixel types
Solution Approach 1:
Different regions of the pixel array are assigned different pixel types based on local lighting conditions. Linear pixels with higher quantum efficiency are positioned where low light detection is critical, while logarithmic pixels with saturation resistance are positioned for high light level areas, optimizing local performance throughout the array.
Solution Approach 2:
A dual demosaicing algorithm acts as an intermediary processing step that separately processes linear and logarithmic pixel data through dedicated interpolation filters, then combines the results to produce a unified high-quality image that leverages the strengths of both pixel types without suffering from their individual weaknesses.
4Ease of operation
If traditional demosaicing algorithms are used on dual pixel array, then processing simplicity is maintained, but output image quality is unsuitable
Solution Approach 1:
A dual demosaicing algorithm acts as an intermediary processing step that separately processes linear and logarithmic pixel data through dedicated interpolation filters, then combines the results to produce a unified high-quality image that leverages the strengths of both pixel types without suffering from their individual weaknesses.
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 method effectively expands the dynamic range of image sensors, preventing saturation and producing a continuous output across varying light levels, resulting in improved image quality with both linear and logarithmic pixels.
Implementation Method 1
charge is collected in a photoelectric conversion device of the pixel circuit as a result of impinging light
Implementation Method 2
charge is collected in a photoelectric conversion device of the pixel circuit as a result of impinging light
Data Source
AI summary
A signal processing circuit, a method of processing an image, and an imaging device are disclosed. In one example of the present disclosure, the signal processing circuit includes image processing circuitry configured to receive a first set of signals corresponding to linear pixels in an array of pixels, receive a second set of signals corresponding to logarithmic pixels in the array of pixels, perform a linear pixel interpolation using the first set of signals to determine a linear rgb value associated with a given pixel in the array of pixels, perform a logarithmic pixel interpolation using the second set of signals to determine a logarithmic RGB value associated with the given pixel in the array of pixels, and combine the linear rgb value and the logarithmic RGB value to generate a combined pixel value associated with the given pixel in the array of pixels.