Pixel Structure Unit Exposure Control for HDR Imaging
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Solution Overview
Problem
Current methods for generating high-dynamic range (HDR) images in mobile devices face challenges such as noise increase during long exposure, leading to reduced sharpness and potential over-exposure in bright scenes, which affects the overall image quality.
Innovation Solution
A method involving an image sensor with a pixel array and a filter array, where each filter unit covers multiple pixel units to form a pixel structure unit, allowing for separate exposure control with different exposure times for different pixel units within each structure unit, and combining their outputs to generate a single-frame HDR image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If long exposure time is used to capture HDR images, then brightness and dynamic range are improved, but noise increases and sharpness decreases
Solution Approach 1:
The pixel array is divided into multiple pixel structure units, where each unit contains multiple pixel units under a single filter unit. Different pixel units within the same structure unit are assigned different exposure times (first exposure time for bright regions, second exposure time for dark regions), allowing selective exposure control to reduce noise while maintaining brightness.
Solution Approach 2:
Different regions of the image receive different exposure treatments based on local brightness characteristics. Bright regions use shorter exposure times to avoid overexposure and noise, while dark regions use longer exposure times to capture sufficient light, achieving locally optimized image quality throughout the scene.
2Illumination intensity
If long exposure time is used to capture HDR images, then dynamic range is improved, but image sharpness decreases
Solution Approach 1:
The image sensor is segmented into multiple pixel structure units with different exposure characteristics. By combining data from pixel units with different exposure times within each structure unit, the system achieves high dynamic range while maintaining sharpness through selective use of short-exposure data for bright regions.
Solution Approach 2:
Instead of uniformly applying long exposure to the entire sensor, only necessary pixel units (those capturing dark regions) receive long exposure. Pixel units capturing bright regions use short exposure, avoiding the sharpness degradation that would occur with uniform long exposure across the entire image.
3Illumination intensity
If separate exposure control is applied to different pixel units, then HDR quality is improved, but device complexity increases
Solution Approach 1:
Multiple pixel units with different exposure characteristics are merged into unified pixel structure units, each containing pixel units that share the same filter unit. This merging allows the system to process and combine data from multiple exposure times while maintaining a manageable structural organization, reducing the complexity burden of separate exposure control.
Solution Approach 2:
Each pixel structure unit serves multiple functions: it captures both bright and dark region information through different pixel units, processes multiple exposure times, and can adaptively select which pixel unit data to use based on scene conditions. This multi-functionality reduces the need for separate dedicated systems for different exposure control tasks.
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
This approach results in HDR images with improved brightness, color sharpness, and reduced noise, providing a more realistic and thorough representation of the scene while minimizing damage to image sharpness during interpolation compensation.
Implementation Method 1
An image sensor includes a pixel array and a filter array disposed on the pixel array. Each filter unit in the filter array covers a plurality of pixel units in the pixel array so as to constitute a pixel structure unit.
Data Source
AI summary
The present disclosure provides a method for generating an HDR image. The method includes: providing an image sensor, in which the image sensor includes a pixel array and a filter array disposed on the pixel array, and each filter unit in the filter array covers a plurality of pixel units in the pixel array so as to constitute a pixel structure unit; and performing an exposure control to pixel units within each pixel structure unit respectively, in which a first part of the pixel units within each pixel structure unit are exposed for a first exposure time, a second part of the pixel units within the pixel structure unit are exposed for a second exposure time, and the first exposure time is greater than the second exposure time.