Global-Shutter Monochrome-Color Fusion for Motion and Banding
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Solution Overview
Problem
Rolling shutter RGB cameras face challenges in low light conditions due to motion blur and banding artifacts from artificial lighting, with integration time limitations leading to noisy and under-exposed images.
Innovation Solution
A camera system comprising a monochrome camera with a global shutter and a color camera with a global shutter, synchronized to capture images simultaneously, aligning and transferring color information from the color camera to the monochrome camera to generate a high-quality image, using machine learning for alignment and color synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the integration time of a rolling shutter RGB camera is increased to improve image exposure in low light conditions, then the image brightness is improved, but motion blur increases and banding artifacts appear from artificial lighting
Solution Approach 1:
The system separates the imaging function into two specialized cameras: a monochrome camera for high-sensitivity luminance capture and a color camera for color information. This segmentation allows each camera to be optimized for its specific function, with the monochrome camera capturing bright images without motion blur using global shutter, while the color camera provides color data that is later merged with the monochrome image.
Solution Approach 2:
The system combines the luminance information from the monochrome camera with the color information from the color camera to produce a final high-quality image. This merging of data from two different camera systems allows the benefits of both cameras to be realized simultaneously, achieving high brightness without motion blur while maintaining color accuracy.
2Object-affected harmful factors
If the integration time is decreased to reduce motion blur, then motion blur is reduced, but the images become noisy and under-exposed
Solution Approach 1:
The imaging task is divided between two cameras with different strengths. The monochrome camera, with its higher sensitivity and global shutter, is responsible for capturing the luminance information with proper exposure and without motion blur. The color camera captures color information simultaneously. This segmentation allows the monochrome camera to use optimal integration time for exposure without suffering from the trade-offs that limit rolling shutter cameras.
Solution Approach 2:
The system uses the monochrome camera to create a high-quality luminance copy of the scene that is then combined with color information. The monochrome image serves as a template or base that captures the scene's brightness distribution accurately, which is then enhanced with color data rather than being degraded by noise or under-exposure.
3Speed
If a rolling shutter camera is used to capture images in real-time, then the capture speed is maintained, but banding artifacts appear due to alternating current and dimmer controls
Solution Approach 1:
The system replaces the rolling shutter camera with a global shutter monochrome camera for the critical luminance capture function. The global shutter architecture captures the entire scene simultaneously, eliminating the sequential row-by-row capture that causes banding artifacts from AC-powered lighting. This segmentation of the imaging function allows the use of global shutter technology where it is most needed to avoid banding.
Solution Approach 2:
The system merges the banding-free luminance image from the global shutter monochrome camera with the color information from the color camera. By combining these two data streams, the final image inherits the banding-free property from the monochrome channel while maintaining color information, effectively eliminating the banding artifact problem that plagues rolling shutter color cameras.
Data Source
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Figure 2A~2B
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AI summary
A camera system includes a monochrome camera, having a global shutter, to capture a first image of a scene, and a color camera, disposed separately from the monochrome camera and having a global shutter, to capture a second image of the scene. The second image is aligned to the first image and color information of the second image is provided to the first image to obtain a third image representing the scene.