Image Sensor Motion Weighting for HDR Color Artifact Prevention
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Solution Overview
Problem
Image devices face issues with color degradation in motion compensation, particularly when using a longer compensation scheme, which can result in color artifacts due to saturation of color channels during white balancing.
Innovation Solution
The image device includes an image sensor and an image signal processor that perform signal pre-processing on long-exposure images to prevent or reduce color artifacts, by determining a weight for detected motion regions and applying it to generate a pre-processed image, which is then white-balanced to maintain accurate color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If motion compensation with longer exposure time is used, then image quality and dynamic range are improved, but color artifacts occur due to saturation of color channels during white balancing
Solution Approach 1:
The patent applies preliminary action by performing signal pre-processing on the first image (long exposure image) before motion compensation and white balancing. Specifically, the processor generates a pre-processed image by adjusting the first image based on the second image (short exposure) and a weight value, preventing color channel saturation before it occurs during subsequent processing steps
Solution Approach 2:
The patent applies local quality by differentiating processing approaches for different regions of the image. Motion regions are identified by comparing the first and second images, and different weight values are applied to motion regions versus non-motion regions. This localized processing prevents color artifacts in motion areas while maintaining image quality in static areas
2Measurement precision
If white balancing is performed on long-exposure images, then color accuracy is improved, but color channel saturation causes color artifacts in motion regions
Solution Approach 1:
The patent performs preliminary action by pre-processing the long-exposure image before white balancing. The processor generates a pre-processed image by combining information from both long and short exposure images with appropriate weighting, preventing color channel saturation before the white balancing operation is applied
Solution Approach 2:
The patent introduces an intermediary element - the pre-processed image - that mediates between the original long-exposure image and the final white-balanced image. This intermediate processing step adjusts the image data to prevent saturation while preserving color accuracy information
Data Source
AI summary
An operation method of an image sensor includes detecting a motion region based on a first image and a second image to obtain a detected motion region, the first image corresponding to a first exposure time and the second image corresponding to a second exposure time, the second exposure time being shorter than the first exposure time, determining a weight for the detected motion region, performing signal pre-processing on the first image to generate a pre-processed image, and outputting a third image based on the pre-processed image and the weight.