Composite Lens Shading Correction for Image Artifacts
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Solution Overview
Problem
Smaller form factor electronic devices, such as smartphones and tablets, face challenges in image quality due to non-uniform light distribution across the image sensor, leading to color artifacts and shading distortions, which conventional lens shading correction (LSC) algorithms inadequately address.
Innovation Solution
An enhanced LSC algorithm that implements a multi-phase approach, including characterization and correction phases, to create and select LSC tables based on pre-processing analysis, effectively reducing color artifacts and improving image quality by generating a composite LSC table as a weighted sum of individual tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional LSC algorithms are used in smaller form factor devices, then device miniaturization is achieved, but color artifacts and shading distortions occur
Solution Approach 1:
The patent segments the image into multiple regions (center region and peripheral regions) and applies different LSC tables to different regions. This allows the center region to use a first LSC table optimized for central pixels while peripheral regions use second LSC tables optimized for their specific locations, thereby reducing color artifacts and shading distortions in smaller form factor devices without compromising overall image quality
Solution Approach 2:
The patent implements local quality by creating region-specific LSC tables that are tailored to the unique characteristics of different image regions. The first LSC table is optimized for the center region while second LSC tables are optimized for respective peripheral regions, allowing each region to receive correction parameters suited to its specific optical characteristics rather than applying a uniform correction across the entire image
2Manufacturing precision
If multiple LSC tables are generated and processed, then color artifact reduction is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-generating multiple LSC tables during device manufacturing or initialization, storing them in memory for later use. The first LSC table and multiple second LSC tables are created in advance based on optical characterization, so that during image processing, the system only needs to select and apply the appropriate pre-computed tables rather than calculating corrections in real-time, thereby reducing computational complexity while maintaining color artifact reduction capabilities
Solution Approach 2:
The patent applies partial action by selectively processing only the peripheral regions with dedicated second LSC tables, while the center region uses the first LSC table. This partial application of multiple correction tables focuses computational resources on the regions that most need correction (peripheral regions where shading artifacts are most prominent) rather than uniformly applying complex corrections to the entire image, thus balancing color artifact reduction with computational efficiency
Data Source
AI summary
Techniques for reducing color artifacts in a digital image are described. In one embodiment, for example, an apparatus may comprise logic, at least a portion of which is in hardware, the logic to determine a respective set of error values for each of a set of lens shading correction (LSC) tables, each set of error values describing error associated with application of its corresponding LSC table to a preprocessed image, determine a respective weight for each of the set of LSC tables based on the corresponding set of error values for that LSC table, and generate a composite LSC table for the preprocessed image as a weighted sum of the set of LSC tables, based on the respective weights for the set of LSC tables. Other embodiments are described and claimed.