Single-Shot HDR Sensor Motion Compensation
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Solution Overview
Problem
Handheld camera devices, such as smartphones, face challenges in capturing high-dynamic-range images due to insufficient bit depth, leading to motion artifacts when objects move between short and long exposure times, even with dual-exposure-time single-shot image sensors.
Innovation Solution
A method for generating motion-compensated high-dynamic-range (HDR) images by determining a motion parameter from pixel values of short- and long-exposure-time pixels and demosaicing to weight their contributions, ensuring accurate depiction of both bright and dark areas without artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multi-shot HDR imaging with separate short and long exposure images is used, then dynamic range is improved, but motion artifacts occur when the scene is not static
Solution Approach 1:
The patent combines short-exposure and long-exposure imaging into a single-shot process using a dual-exposure-time single-shot HDR color image sensor. The sensor integrates both exposure times simultaneously across different pixel regions, merging the capture of bright and dark areas in one operation to eliminate motion artifacts while maintaining extended dynamic range.
Solution Approach 2:
The image sensor is segmented into multiple pixel types within the same sensor array, including pixels dedicated to short exposure time and pixels dedicated to long exposure time. This segmentation allows different regions of the sensor to capture different exposure durations simultaneously, enabling HDR imaging without temporal separation.
2Illumination intensity
If dual-size pixels are integrated in the same pixel array for single-shot HDR, then dynamic range benefit is achieved, but manufacturing complexity increases significantly
Solution Approach 1:
The patent implements local quality by assigning different exposure time characteristics to different spatial regions of the sensor array. Specifically, certain pixel regions are configured for short exposure while other regions are configured for long exposure, allowing each local area to have optimized properties for its intended function without requiring complex dual-size pixel integration throughout the entire sensor.
3Reliability
If overlapping exposure times are used in single-shot HDR sensors, then motion artifacts are reduced, but image quality still degrades due to differences in exposure times
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the weighting parameters used to combine pixel values from short-exposure and long-exposure regions. The weighting parameter is determined based on scene characteristics and exposure time differences, allowing optimal blending of the two exposure types to minimize both motion artifacts and quality degradation. This adaptive parameter adjustment enables the system to compensate for the inherent differences between short and long exposure captures.
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
The solution effectively reduces motion artifacts in HDR images by compensating for motion, allowing for accurate representation of scene details across varying exposure times, enhancing image quality in dynamic scenes.
Implementation Method 1
an image sensor having a bit depth of 8 bits or may be 10 bits... pixel values generated by a local region of respective sensor pixels
Data Source
AI summary
A method for generating an high-dynamic-range (HDR) color image from a dual-exposure-time single-shot HDR color image sensor includes obtaining pixel values generated by a local region of sensor pixels of the image sensor, determining a motion parameter for the local region from pixel values associated with a first color, and demosaicing the pixel values of the local region to determine, for each of three colors, an output value of the images pixel, wherein relative contributions of short-exposure-time pixels and long-exposure-time pixels to the output value are weighted according to the motion parameter. A method for generating an HDR color image from a triple-exposure-time single-shot HDR color image sensor includes generating a first dual-exposure-time HDR image from short-exposure-time and medium-exposure-time pixel values, generating a second dual-exposure-time HDR image from medium-exposure-time and long-exposure-time pixel values, and generating a triple-exposure-time HDR color image from the first and second dual-exposure-time HDR images.