Image Processing Filter Phase Alteration for Resampling
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Solution Overview
Problem
Existing image data signal resampling techniques face challenges in achieving efficient and high-quality image scaling due to non-integer group delays, which result in undesirable artefacts such as blurring and distortion during image display.
Innovation Solution
The implementation of a filter that resamples image data signals by a specific factor and applies a phase alteration to compensate for group delays, shifting non-integer group delays to integer values, thereby improving image quality through the use of cascaded integrator-comb filters and polyphase filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional resampling techniques are used, then the resampling process can be implemented, but non-integer group delays cause blurring and distortion artefacts in the output image
Solution Approach 1:
The patent applies preliminary anti-action by introducing a phase alteration filter that pre-compensates for the non-integer group delay effects before the resampling process completes. This compensation filter is designed to counteract the expected blurring and distortion artefacts that would otherwise be generated by the resampling operation, thereby preventing rather than correcting the harmful effects.
Solution Approach 2:
The patent changes the phase parameter of the image data signal by applying a phase alteration that shifts the group delay from non-integer to integer values. This parameter transformation modifies the temporal characteristics of the signal processing, converting the harmful non-integer group delay into a beneficial integer group delay that does not produce artefacts.
2Manufacturing precision
If complex filtering methods are applied to improve image quality, then artefacts can be reduced, but computational complexity and architectural complexity increase
Solution Approach 1:
The patent segments the resampling process into distinct functional blocks: a phase alteration filter stage and a resampling stage. This segmentation allows each block to be optimized independently, with the phase alteration filter preparing the signal to reduce artefacts and the resampling block performing the sample rate conversion, thereby managing complexity through modular design.
Solution Approach 2:
The patent performs preliminary action by applying the phase alteration filter before the resampling operation. This preliminary processing modifies the input signal characteristics so that the subsequent resampling process generates minimal artefacts, reducing the need for complex post-processing and lowering overall computational complexity.
Data Source
AI summary
Examples of the present disclosure relate to an image processing apparatus comprising a filter to convert a first image data signal into an output image data signal. The filter is configured to resample the first image data signal, having a first sample rate, by a resampling factor, such that the output image data signal has an output sample rate that is different to the first sample rate. The filter is also configured to apply a phase alteration to the first image data signal to compensate a group delay in the first image data signal.