Adaptive Interpolation Kernel for Image Rescaling Sharpness and De-ringing
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Solution Overview
Problem
Conventional digital image rescaling methods, such as bilinear and bicubic interpolation, suffer from image quality issues like blurring, aliasing, and staircase edges, while 8-tap interpolation reduces these issues but introduces ringing artifacts and lacks flexibility in sharpness control.
Innovation Solution
A digital video rescaling system using an adaptive 8-tap interpolation kernel with sharpness and de-ringing control, which generates interpolated pixels based on input support pixels and adjusts sharpness and ringing effects using control parameters, maintaining high-frequency quality and reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 8-tap interpolation is used to improve high-frequency reconstruction and reduce aliasing, then image quality in high-frequency region is improved, but ringing artifacts are introduced along edges
Solution Approach 1:
The patent applies local quality by using different filter kernels for different regions of the image. Specifically, it identifies edge regions and applies a modified kernel that prevents ringing artifacts, while using the full 8-tap kernel in non-edge regions to maintain high-frequency reconstruction quality. This region-specific approach allows the system to achieve both high-frequency fidelity and artifact-free edges.
Solution Approach 2:
The patent changes the parameters of the interpolation kernel based on local image characteristics. It dynamically adjusts the kernel coefficients depending on whether the current pixel location is near an edge or in a smooth region. This parameter adaptation allows the system to optimize for both high-frequency preservation and ringing suppression in different contexts.
2Manufacturing precision
If conventional 8-tap interpolation is used to reduce staircase and aliasing issues, then image reconstruction is improved, but the system lacks flexibility in sharpness control
Solution Approach 1:
The patent introduces dynamic sharpness control by allowing the interpolation kernel parameters to be adjusted based on desired output characteristics. The system can adaptively modify the kernel coefficients to achieve different levels of sharpness while maintaining reconstruction quality. This makes the system versatile for different application requirements rather than being fixed to a single interpolation mode.
Solution Approach 2:
The patent creates a universal interpolation system that can serve multiple functions: standard high-quality interpolation, sharpness enhancement, and artifact suppression. By incorporating controllable parameters and adaptive kernel selection, the single system can handle various image processing needs without requiring separate specialized filters for each function.
3Device complexity
If linear interpolation techniques (bilinear or bicubic) are used for rescaling, then device complexity is low, but image quality suffers from blurring, aliasing, and staircase edges
Solution Approach 1:
The patent segments the image processing task by dividing it into distinct regions (edge regions vs. non-edge regions) and applying different interpolation strategies to each segment. This allows the system to use simpler filters in smooth regions while applying more sophisticated edge-aware filtering only where necessary, thus balancing complexity and quality.
Solution Approach 2:
The patent applies partial action by using the full computational power of 8-tap interpolation only in regions where it is most beneficial (edge regions with high-frequency content), while using simpler interpolation in smooth regions. This selective application reduces overall computational complexity while maintaining image quality where it matters most.
Data Source
AI summary
A digital video rescaling system is provided. The system includes an image data input configured to receive input support pixels y1 to yn and a sharpness control module configured to generate a sharpness control parameter Kshp. The system further includes an interpolated pixel generator configured to use an adaptive interpolation kernel to generate an interpolated pixel ys based on the input support pixels, and adjust a sharpness of the interpolated pixel ys based at least partly upon the sharpness control parameter Kshp. The system also includes a de-ringing control unit to adjust the ringing effect of the interpolated pixel based on a local image feature Kfreq, and an output module configured to output the adjusted interpolated pixel for display.