Phase-Controlled M/N Filter for Image Downscaling
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Solution Overview
Problem
Existing image scaling methods face challenges in achieving high-quality downscaling from a larger number of input samples to a smaller number of output samples, particularly in maintaining constant phase and stop band rejection, which can result in visually undesirable images due to phase jitter and uneven sample delays.
Innovation Solution
The method involves using a phase-controlled M/N filter that scales input samples relative to the phase of output samples, normalizes the sum to achieve unity gain, and initializes the sum with a scaled version of the input sample to control phase delay, effectively combining the averaging quality of M/N filtering with the constant phase of linear interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional M/N filtering is used for downscaling, then averaging quality is achieved, but phase jitter and uneven sample delays occur resulting in visually undesirable images
Solution Approach 1:
The patent applies dynamics by making the filter coefficients adaptive rather than fixed. The phase-controlled M/N filter dynamically adjusts the weighting of input samples based on their phase relationship with output samples, allowing the system to maintain constant phase response while achieving high-quality downscaling. This dynamic adjustment resolves the contradiction between averaging quality and phase consistency.
Solution Approach 2:
The patent changes the parameter of filter coefficients from static to dynamic based on phase information. By modifying the weighting parameters according to the phase of output samples, the system achieves both good averaging performance and constant phase response, resolving the contradiction between measurement precision and stability.
2Stability of the object's composition
If phase-controlled M/N filter is used, then constant phase and stop band rejection are achieved, but filter complexity increases
Solution Approach 1:
The patent merges the M/N filtering structure with phase control mechanisms into a unified filter architecture. By combining the averaging function with phase-aware coefficient adjustment, the system achieves constant phase response without requiring completely separate complex processing stages, thus managing the complexity while improving phase stability.
Solution Approach 2:
The phase-controlled M/N filter performs multiple functions: it averages input samples, controls phase response, and provides stop band rejection all within a single filter structure. This multi-functionality reduces the need for separate processing stages, managing overall system complexity while achieving multiple performance goals simultaneously.
3Device complexity
If simple averaging is used for downscaling, then computational complexity is low, but phase delay varies causing visual artifacts
Solution Approach 1:
The patent introduces dynamic phase control to the averaging process, making the filter coefficients adaptive based on phase information. This dynamic approach maintains relatively low computational complexity while significantly improving sample delay consistency, resolving the contradiction between simplicity and phase stability.
Data Source
AI summary
A method and apparatus for down scaling image data is disclosed. One method controls a phase for an M/N filter, where N represents a number of input samples, and M represents a number of output samples. N is greater than M. Another method may switch between an M/N filter and a phase-controlled M/N filter.