Image Sensor Variable Weighting Factor High Dynamic Range
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Solution Overview
Problem
Conventional image sensors face limitations in capturing high dynamic range images due to the difference between the scene's dynamic range and the sensor's dynamic range, leading to loss of details in high and low light levels, which existing techniques struggle to overcome effectively.
Innovation Solution
The technique involves applying a variable weighting factor to a sample from a long exposure time to reduce or eliminate the contribution of saturated photosensitive semiconductors by combining it with a sample from a short exposure time, using a combining scheme that adjusts the weighting based on the saturation level of the long exposure time sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long exposure time is used to capture low light level details, then the dynamic range coverage is improved, but the photosensitive semiconductor becomes saturated causing loss of high light level details
Solution Approach 1:
The patent segments the exposure process into multiple discrete exposure times (e.g., first exposure time and second exposure time) rather than using a single long exposure. This allows different regions of the image to be captured at different exposure levels, preventing saturation in high light level regions while maintaining sensitivity in low light level regions.
Solution Approach 2:
The patent dynamically adjusts the exposure time based on the light level of each pixel region. By varying the exposure time between different pixel groups or over time, the system adapts to different lighting conditions in the scene, ensuring optimal capture quality without saturation across the entire dynamic range.
2Loss of information
If a short exposure time is used to avoid saturation, then the high light level details are preserved, but the low light level details are lost due to insufficient light accumulation
Solution Approach 1:
The imaging process is divided into multiple exposure segments with different exposure times. Some segments use short exposure times to capture high light level details without saturation, while other segments use longer exposure times to accumulate sufficient light for low light level details, thereby resolving the contradiction between these two requirements.
Solution Approach 2:
The patent merges multiple exposed images with different exposure times into a single composite image. By combining the short exposure image (good for highlights) and long exposure image (good for shadows) through merging operations, the system achieves extended dynamic range that preserves both high and low light level details.
3Measurement precision
If multiple images of different exposure times are captured and combined, then the dynamic range is extended, but the processing complexity and time consumption increase
Solution Approach 1:
The patent performs preliminary actions by capturing multiple images with different exposure times in advance, organizing them in a structured manner. This pre-prepared multi-exposure data can then be efficiently processed and combined, reducing the real-time processing complexity while still achieving extended dynamic range.
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 method enhances the dynamic range of the sensor by effectively reducing the contribution of saturated samples, allowing for the capture of a higher dynamic range image by combining samples from different exposure times, thereby preserving details in both high and low light levels.
Implementation Method 1
a photosensitive semiconductor of the pixel cell to become saturated
Data Source
AI summary
This disclosure describes techniques for producing high dynamic range images by applying a variable weighting factor to a sample prior to combining the sample with another sample. In one example, a method includes sampling a first pixel cell signal at a first time to produce a first sample, sampling a second pixel cell signal at a second time to produce a second sample, applying a variable weighting factor to the second sample, wherein the variable weighting factor is defined based on a function, and combining the first sample and the weighted second sample.