Spatially-Adaptive Filter for Interference Pattern Removal

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Solution Overview

Problem

Conventional systems for transforming hard-copy documents to digital images often suffer from interference patterns, such as moiré patterns, which degrade the visual quality and accuracy of digital images, affecting operations like image-based search and big data analysis.

Innovation Solution

A digital image creation system employs a spatially-adaptive filter that adapts smoothing based on the distance from edges and variance in color and luminance to selectively remove interference patterns while preserving object edges, using context data generated for individual pixels to construct filters that apply varying amounts of smoothing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a lossy filter is applied to remove interference patterns, then the visual quality is improved, but object edges may be blurred or lost

Engineering Contradiction:

Improveinterference patternsVSAvoidedge sharpness

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies different filtering strengths to different regions of the image based on local characteristics. The spatially-adaptive filter adjusts its smoothing parameter sigma according to the local variance and gradient magnitude, applying stronger filtering to uniform regions and weaker filtering to edge regions, thus removing interference patterns while preserving edge sharpness

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The filter parameters are dynamically adjusted for each pixel based on local image characteristics rather than using a fixed global parameter. The sigma value is computed adaptively using local variance and gradient information, allowing the filter to respond dynamically to different regions and effectively resolve the contradiction between noise removal and edge preservation

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If conventional filtering is applied to remove interference patterns, then the visual quality is improved, but accuracy in image-based operations is reduced

Engineering Contradiction:

Improveinterference patternsVSAvoidimage-based search accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

By applying spatially-adaptive filtering that preserves local structures and edges, the method maintains the structural integrity of the image content. This local preservation ensures that image-based operations such as search and analysis can accurately identify and process relevant features without being degraded by over-smoothing

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent replaces conventional mechanical filtering approaches with a statistically-based adaptive filtering method. Instead of using fixed kernel operations, the filter uses locally-computed variance and gradient statistics to determine appropriate smoothing parameters, thereby preserving image semantics while removing interference patterns

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If a spatially-adaptive filter is constructed using context data including distance from edges, then edge preservation is improved, but device complexity increases

Engineering Contradiction:

Improveedge preservationVSAvoidfilter construction complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The filtering process is segmented into distinct computational stages: first computing local variance, then computing gradient magnitude, then determining sigma based on these intermediate results. This segmentation of the filter construction process makes the complex adaptive filtering more manageable and computationally efficient while maintaining edge preservation capabilities

Inventive Principle:

Principle #1Segmentation

4Object-affected harmful factors

If spatially-adaptive filtering is applied to all pixels, then interference pattern removal is improved, but processing time increases

Engineering Contradiction:

Improveinterference pattern removal effectivenessVSAvoidimage processing time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The filter applies full adaptive processing only where necessary (in regions with interference patterns), while using simpler filtering or no filtering in regions where interference patterns are absent. This partial application of the complex adaptive filter reduces overall processing time while maintaining effectiveness in critical regions

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10134113B1Digital media environment for removal of interference patterns from digital images

Publication Date: 2018.11.20 ADOBE INC

AI summary

Techniques for removal of interference patterns from digital images are described, in which a spatially-adaptive filter is applied to a pixel based on a context of the pixel. In an example, an edge of an object in a digital image is located in a digital image creation system. Then, context data is generated for a pixel in the digital image. The context data includes a distance from the edge of the object to the pixel. The digital image creation system can also generate color data and luminance data for the pixel, representing a similarity of color and luminance between the pixel and surrounding pixels within the digital image. Then, the digital image creation system constructs a spatially-adaptive filter for the pixel based on the context data for the pixel. The digital image creation system removes an effect of the interference pattern at the pixel in the digital image by applying the spatially-adaptive filter to the pixel.