High Resolution Thin Multi-Aperture Imaging Systems
Patent No. USRE48444 (titled "High Resolution Thin Multi-Aperture Imaging Systems") was filed by Corephotonics Ltd on Apr 14, 2019.
What is this patent about?
’444 is related to the field of multi-aperture imaging systems , specifically those used in thin cameras, such as those found in mobile phones. The background acknowledges the increasing demand for optical zoom in mobile devices, a feature traditionally limited by camera height constraints and the trade-offs between image quality, cost, and mechanical reliability. Existing solutions, like mechanical zoom or oversampling, present their own drawbacks in terms of size, cost, and performance.
The underlying idea behind ’444 is to enhance image resolution and color fidelity in multi-aperture cameras by strategically employing non-standard color filter arrays (CFAs) on at least one of the sensors. This approach aims to overcome the limitations of standard CFAs, particularly in scenarios where one sensor captures a wider field of view and the other captures a zoomed-in view, by improving the color sampling rate in the overlapping region of the sensors.
The claims of ’444 focus on a multi-aperture imaging system comprising two cameras. One camera has a sensor covered, at least partially, with a non-standard CFA designed to increase a specific color sampling rate compared to a standard CFA. The second camera has a sensor that is either clear or covered with a standard CFA. The system includes a processor that fuses the images from both cameras, registering pixels in the overlapping area. The non-standard CFA includes a repetition of a n×n micro-cell where n=4 and wherein each micro-cell includes a BBRR-RBBR-RRBB-BRRB color filter order.
In practice, the system captures two images, one with a wider field of view and potentially a lower zoom factor, and another with a narrower field of view and a higher zoom factor. The sensor with the non-standard CFA is typically used for the wider field of view, with the non-standard CFA covering the area that overlaps with the narrower field of view of the other sensor. The processor then registers the two images, aligning them based on luminance information, and fuses them to create a final image with improved color resolution and potentially a higher zoom factor. The registration process involves low-pass filtering on the second Luma image in order to match its spatial frequency content to that of the first Luma image and to generate a low-pass second Luma image, and applying registration on the low-pass second Luma image and the first Luma image.
This design differentiates itself from prior approaches by intelligently distributing color information capture between the sensors. By using a non-standard CFA in the overlapping region, the system can capture more color information than would be possible with a standard CFA, especially when the other sensor uses a clear filter or a standard CFA. This allows the system to create a higher-resolution, more color-accurate final image without requiring excessively high-resolution sensors or complex mechanical zoom mechanisms. The fusion process , combining luminance and color data from different sensors, is key to achieving the desired image quality.
How does this patent fit in bigger picture?
Technical landscape at the time
In the early 2010s when ’444 was filed, digital cameras in mobile devices were becoming increasingly common, at a time when manufacturers were striving to improve image quality and features while reducing device size. Optical zoom was a desirable feature, but hardware or software constraints made it non-trivial to implement in thin mobile devices. At a time when zoom was typically implemented using mechanical zoom solutions, these were often too thick for mobile phones. Dual-aperture imaging systems were being explored as an alternative, but known systems often traded off functionalities such as zoom and color resolution.
Novelty and Inventive Step
The examiner allowed the claims because the multi-aperture imaging system includes a specific color filter array (CFA) arrangement. Claim 1 recites a CFA with a repeating n x n micro-cell where n=4 and the micro-cell has a BBRR-RBBR-RRBB-BRRB color filter order. Claim 2 recites a CFA with a repeating n x n micro-cell where n=6 and the micro-cell has a color filter order selected from a specific group. Other claims depend on these features, and the examiner found the claimed combinations to be allowable.
Claims
This patent contains 24 claims, with independent claims numbered 1, 2, 4, 6, 12, and 20. The independent claims are generally directed to multi-aperture imaging systems that use multiple cameras with different color filter arrays to generate a fused output image. The dependent claims generally add further details and limitations to the elements and features described in the independent claims.
Key Claim Terms New
Definitions of key terms used in the patent claims.
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Date
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USRE48444
- Application Number
- US16383618
- Filing Date
- Apr 14, 2019
- Status
- Granted
- Expiry Date
- Nov 23, 2033
- External Links
- Slate, USPTO, Google Patents