3D Cameras for HDR Using Multi-Exposure Normalization
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Solution Overview
Problem
Existing cameras, including stereoscopic ones, struggle to capture high dynamic range (HDR) images due to the high cost of image sensors capable of wide luminance levels and the resulting high data processing requirements, making it economically and technically unfeasible for small devices like wireless handsets to support HDR image acquisition, especially in 3D formats.
Innovation Solution
A method for generating 2D or 3D HDR images using stereoscopic cameras with relatively narrow dynamic range sensors by setting different exposure settings for each camera element, normalizing pixels, computing disparity, and shifting frames to a common reference, allowing for the creation of HDR images without the need for expensive sensors, thereby reducing data volume and processing demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive image sensors with wide luminance levels are used, then HDR image quality is improved, but device cost and data processing requirements increase significantly
Solution Approach 1:
The patent divides the HDR capture task into multiple SDR captures taken at different exposure times. Instead of using a single expensive sensor with wide luminance capability, the system segments the dynamic range into multiple manageable ranges and captures them separately through time-based exposure variation.
Solution Approach 2:
The patent creates multiple copies of the same scene at different exposure levels and combines them computationally. Rather than relying on a single sensor with inherent wide luminance response, the system takes multiple copies of the scene with varying exposure settings and synthesizes the HDR result from these copies.
2Measurement precision
If expensive HDR-capable image sensors are deployed, then HDR image acquisition capability is improved, but data volume and processing power requirements increase
Solution Approach 1:
The patent takes multiple captures beyond what a single SDR sensor would normally take, using more captures than strictly necessary but with simpler processing per capture. This approach trades the number of captures for the complexity of individual processing operations, ultimately reducing overall system complexity.
Solution Approach 2:
The patent changes the exposure parameter across multiple captures rather than changing the sensor's luminance response characteristics. By varying exposure time—a simple controllable parameter—the system achieves HDR capability through parameter variation rather than through complex sensor design.
3Measurement precision
If stereoscopic cameras with HDR capability are implemented, then 3D HDR image quality is improved, but device footprint and cost increase
Solution Approach 1:
The patent segments the HDR stereoscopic capture into multiple SDR stereoscopic captures at different exposures. This allows the use of smaller, less expensive camera elements that would be required for each individual SDR capture, rather than requiring each element to have full HDR capability independently.
Solution Approach 2:
The patent makes the camera elements universal by using them for both 3D capture and HDR capture through computational processing. The same camera elements that capture stereoscopic images are also used to capture HDR information through multi-exposure techniques, eliminating the need for specialized HDR-only components.
Data Source
AI summary
High dynamic range 3D images are generated with relatively narrow dynamic range image sensors. Input frames of different views may be set to different exposure settings. Pixels in the input frames may be normalized to a common range of luminance levels. Disparity between normalized pixels in the input frames may be computed and interpolated. The pixels in the different input frames may be shifted to, or stay in, a common reference frame. The pre-normalized luminance levels of the pixels may be used to create high dynamic range pixels that make up one, two or more output frames of different views. Further, a modulated synopter with electronic mirrors is combined with a stereoscopic camera to capture monoscopic HDR, alternating monoscopic HDR and stereoscopic LDR images, or stereoscopic HDR images.