Circuit Correcting Lateral Chromatic Aberration Using Virtual Pixels
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Solution Overview
Problem
Image processing pipelines do not effectively account for chromatic aberration caused by wide-angle lenses, leading to color fringing in images due to misaligned focal points among red, green, and blue color channels, which increases CPU bandwidth consumption and power usage.
Innovation Solution
A circuit for correcting lateral chromatic aberration in image sensors using interpolation of pixel values with specific coefficients to align virtual pixel values, reducing color fringing by generating corrected versions of pixel values in both vertical and horizontal directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide-angle lens is used to generate image data, then the field of view and coverage area are improved, but lateral chromatic aberration occurs causing color fringing due to misaligned focal points among different color channels
Solution Approach 1:
The patent applies preliminary action by pre-calculating offset values for each pixel position that represent the lateral chromatic aberration displacement. These offset values are stored in a lookup table before image processing occurs. During actual image processing, the circuit simply retrieves and applies these pre-computed offsets to shift pixel values in red and blue channels relative to the green channel, thereby correcting color fringing without requiring real-time complex calculations.
Solution Approach 2:
The patent introduces an intermediary mechanism by using virtual pixels as intermediate representations. The circuit generates virtual pixel values by interpolating between actual pixels using the pre-calculated offsets. These virtual pixels serve as mediators that align the different color channels (red, green, blue) to their correct positions, effectively eliminating color fringing while preserving the wide-angle field of view.
2Object-affected harmful factors
If image processing is performed on the CPU to correct chromatic aberration, then image quality is improved, but CPU bandwidth consumption and power usage increase significantly
Solution Approach 1:
The patent replaces the mechanical system of general-purpose CPU processing with a specialized hardware image processing circuit. This dedicated circuit is designed specifically for chromatic aberration correction and operates in parallel with the image sensor, eliminating the need to transfer image data to the CPU for correction. The hardware circuit performs interpolation and pixel shifting operations directly using lookup tables and simple arithmetic logic, dramatically reducing power consumption while maintaining correction effectiveness.
3Adaptability or versatility
If software programs are used on CPU for image processing corrections, then flexibility and adaptability are improved, but processing speed and efficiency decrease due to CPU bandwidth constraints
Solution Approach 1:
The patent applies segmentation by dividing the image processing pipeline into dedicated hardware modules, each handling specific correction tasks. The chromatic aberration correction circuit is segmented into separate units for offset lookup, pixel value interpolation, and channel alignment operations. This modular hardware architecture allows parallel processing of different image data streams simultaneously, achieving high processing speeds while maintaining the ability to adjust correction parameters through configurable lookup tables.
Data Source
AI summary
Embodiments relate to lateral chromatic aberration (LCA) recovery of raw image data generated by image sensors. A chromatic aberration recovery circuit performs chromatic aberration recovery on the raw image data to correct the resulting LCA in the full color images using pre-calculated offset values of a subset of colors of pixels.