Motion Correction for High-Dynamic-Range Imaging Systems
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Solution Overview
Problem
Conventional high-dynamic-range (HDR) imaging systems suffer from misregistration and distortion of moving objects due to differences in exposure times, leading to blurred and elongated object shapes in combined images, especially when using Bayer color filter patterned image sensors.
Innovation Solution
A method involving the generation of a motion mask from sequential image frames, followed by an enlarged motion mask, and a corrected image combination using a soft-switching function to align and combine long-exposure and short-exposure images, effectively addressing misregistration and distortion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple exposure images with different exposure times are used to capture HDR images, then highlight and shadow detail are retained, but moving objects appear blurred and elongated due to misregistration
Solution Approach 1:
The patent segments the image processing by creating a motion mask that separates moving objects from stationary objects. The motion mask is generated by comparing multiple exposure images and identifying regions with significant pixel differences, which correspond to moving objects. This segmentation allows different processing to be applied to moving and stationary regions, resolving the contradiction by preserving detail in stationary regions while correcting distortion in moving regions.
Solution Approach 2:
The patent applies local quality by using a motion mask to identify specific regions containing moving objects and applying motion correction only to those regions. The corrected image is generated by selectively replacing pixel values in motion-affected regions while preserving pixel values in stationary regions. This local approach maintains object shape accuracy for moving objects while preserving the detail retention benefits of multiple exposure for the entire image.
2Measurement precision
If long exposure time is used to retain highlight detail, then highlight detail is preserved, but moving objects become more blurred and elongated
Solution Approach 1:
The patent performs preliminary action by generating the motion mask before final image combination. The motion mask is created by comparing pixel values across multiple exposure images and identifying regions with significant differences. This preliminary identification of moving objects allows the system to prepare correction strategies in advance, selecting pixel values from appropriate exposure images for each region, thereby preserving highlight detail while preventing motion blur in the final combined image.
Solution Approach 2:
The patent applies parameter changes by selectively choosing different exposure time parameters for different image regions. For stationary regions, pixel values from long exposure images are used to preserve highlight detail. For moving regions identified by the motion mask, pixel values are selected from short exposure images or through interpolation to maintain shape accuracy. This dynamic parameter selection resolves the contradiction between highlight detail preservation and moving object shape accuracy.
Data Source
AI summary
Electronic devices may include image sensors and processing circuitry. Image sensors may be used to capture multiple exposure images. Processing circuitry may be used to combine multiple exposure images into high-dynamic-range images. A motion correction method is provided that detects motion between multiple exposure images without using a frame buffer. A noise model is used to separate noise from motion for more accurate motion detection. A dilation operator may be used to enlarge a motion mask generated by the motion detector. Motion-corrected images may be generated from the multiple exposure images using a soft switch based on the motion strength. Motion-corrected multiple exposure images may be combined to generate a motion-corrected HDR image. A smoothing filter may be applied to the motion region of the motion-corrected HDR image. A blooming correction may be used to eliminate color artifacts in the motion-corrected HDR image.