RGB-IR Color Filter Array Interpolation for Edge Preservation
Solution Overview
Problem
Conventional image sensors with color filter arrays (CFAs) face challenges in accurately separating color information due to the lack of wavelength specificity in light detection, leading to artifacts like color bleeding, especially in areas with abrupt changes or sharp edges, and require mechanical IR cut filters that increase device cost and complexity.
Innovation Solution
A modified CFA pattern that includes pixels sensitive only to infrared light, allowing for interpolation techniques to preserve edges and enhance image quality by using demosaicing methods that account for IR information, both during day and night modes, without mechanical actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a typical CFA implementation is used where each pixel has color information for only a single color, then the device complexity is reduced, but color information separation accuracy deteriorates leading to artifacts like color bleeding
Solution Approach 1:
The patent segments the CFA into multiple specialized regions: first color filters for red, green, and blue wavelengths; second color filters for cyan, magenta, and yellow wavelengths; and third color filters for infrared wavelengths. This segmentation allows each pixel to capture specific wavelength information, improving color separation accuracy while maintaining manageable device complexity through systematic organization.
Solution Approach 2:
The patent employs a composite CFA structure combining multiple types of color filters with different spectral characteristics. By integrating filters for visible wavelengths (red, green, blue, cyan, magenta, yellow) and infrared wavelengths into a single array, the system achieves comprehensive light spectrum coverage and improved color information separation without requiring separate sensor systems.
2Measurement precision
If mechanical IR cut filters are used to separate infrared light, then infrared detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts infrared detection capability by incorporating dedicated infrared-sensitive pixels within the CFA array itself. Instead of using a separate mechanical IR cut filter system, the infrared detection function is integrated directly into the sensor array through specialized pixels, eliminating the need for moving mechanical components while maintaining infrared detection accuracy.
Solution Approach 2:
The patent replaces the mechanical IR cut filter system with a static, solid-state solution using infrared-sensitive pixels embedded in the CFA. This substitution eliminates mechanical actuation mechanisms, reducing device complexity and potential failure points while maintaining the ability to accurately detect and separate infrared light information.
3Productivity
If conventional demosaicing techniques are used without IR information, then processing speed is maintained, but image quality deteriorates in areas with abrupt changes or sharp edges
Solution Approach 1:
The patent performs preliminary separation of infrared information from the captured light signal before the main demosaicing process. By pre-processing the infrared channel and using it to guide the interpolation of visible color channels, the system maintains processing efficiency while improving image sharpness and reducing artifacts in areas with abrupt changes or sharp edges.
Solution Approach 2:
The patent uses infrared information as an intermediary to improve visible color channel interpolation. The infrared channel serves as a mediator that provides additional spatial and spectral information, guiding the demosaicing algorithm to produce sharper images with fewer artifacts while maintaining reasonable processing speeds through efficient use of the intermediary data.
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 solution effectively separates color channels, reduces artifacts, and enhances image sharpness and quality across varying lighting conditions without the need for mechanical IR cut filters, thereby simplifying the camera design and reducing costs.
Implementation Method 1
Color filter arrays (CFAs), which are comprised of a mosaic of color filters, are placed over the pixel sensors of the image sensor to capture a mosaic of color information
Data Source
AI summary
Techniques are generally described for color filter array interpolation of image data. A first frame of image data representing a plurality of pixels arranged in a grid may be received. A low pass filter may be used to generate a first luminance value for a first non-green pixel of the plurality of pixels. A first chrominance value of the first non-green pixel may be determined based at least in part on a combination of at least a chrominance value of a first green pixel located adjacent to the first non-green pixel and a chrominance value of a second green pixel located adjacent to the first non-green pixel. A second luminance value for the first non-green pixel may be determined based on a combination of the first chrominance value and the first luminance value. Output values for the first non-green pixel may be determined based at least in part on the second luminance value.