Purple Fringing Reduction via Adjusted Color Correction Matrix
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Solution Overview
Problem
Chromatic aberration, particularly purple fringing, in images captured by cameras is not effectively addressed by existing methods, which can enhance the effect of blue fringing and require additional hardware or complex post-processing, especially in live video streams.
Innovation Solution
A method that involves acquiring a raw image, demosaicing it, and applying an adjusted color correction matrix calibrated to a color rendition chart with added purple fringe data, transforming the purple fringe color into a less saturated or neutral replacement color, such as gray, without adding hardware or processing steps to the image pipeline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing post-processing methods are used to remove purple fringing, then purple fringing can be reduced, but the methods require additional hardware or complex processing steps that increase device complexity and processing time
Solution Approach 1:
The patent combines the purple fringing correction function with the existing color correction matrix operation that is already part of the image processing pipeline. By integrating the correction into a existing processing step rather than adding a separate processing stage, the device complexity is avoided while still achieving the desired correction effect.
Solution Approach 2:
The color correction matrix is made to serve multiple functions: its traditional role of color balancing and the additional function of correcting purple fringing. This multi-functionality allows the system to address chromatic aberration without requiring dedicated hardware or processing steps for purple fringing removal.
2Object-affected harmful factors
If existing post-processing methods are used to remove purple fringing, then purple fringing can be reduced, but the processing time and computational load increase
Solution Approach 1:
The correction operation is merged with the existing color correction matrix application in the image processing pipeline. Since the color correction matrix is already being applied as part of standard image processing, combining the purple fringing correction with this existing operation eliminates the need for additional processing time while achieving the correction goal.
3Adaptability or versatility
If image processing methods such as WDR or HDR are used to improve image quality, then dynamic range is enhanced, but the adverse effects of chromatic aberration are enhanced making blue fringing more prominent
Solution Approach 1:
The patent applies preliminary anti-action by correcting the purple fringing at an early stage in the image processing pipeline, before subsequent processing steps such as WDR or HDR operations are applied. By addressing the chromatic aberration early, the harmful effects are prevented from being amplified by later processing steps while still allowing those steps to enhance the dynamic range.
Solution Approach 2:
The color correction matrix is applied in advance as part of the basic image processing pipeline, preparing the image for subsequent operations. This preliminary correction ensures that when WDR or HDR processing is later applied, the chromatic aberration does not become more prominent, while still allowing the dynamic range enhancement to proceed.
Data Source
AI summary
A method of reducing purple fringing in images captured by a camera, comprises: acquiring a raw image of a scene with an image sensor of the camera, demosaicing the raw image, and applying an adjusted color correction matrix to the demosaiced raw image. The adjusted color correction matrix is deduced by calibrating the spectral response of the image sensor to a color rendition chart to which the color data of a purple fringe has been added, and furthermore the color correction matrix is adjusted such that the image sensor response for color values of the purple fringe is transformed into color values of a predetermined replacement color following application of the color correction matrix.