Auto-regressive Edge-directed Interpolation with Backward Projection

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Solution Overview

Problem

Existing image and video interpolation techniques fail to effectively capture fast-changing characteristics and local details of textures, edges, and object contours, leading to noticeable blurring and distortion when up-sampling low-resolution content for high-resolution displays.

Innovation Solution

The implementation of auto-regressive edge-directed interpolation with a backward projection constraint (AR-EDIBC) adapts filtering coefficients to local image characteristics, using forward prediction and backward projection to determine reliable pixel values, and selectively applies different interpolation methods based on content and computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If bi-linear interpolation is used to up-sample images, then computational complexity is reduced, but edge details are lost and blurring occurs

Engineering Contradiction:
Improvecomputational complexityVSAvoidedge detail preservation
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent implements dynamic adaptation of interpolation weights based on local image characteristics. The algorithm detects edges and textures in different regions and adjusts filtering parameters accordingly, transitioning from static pre-defined weights to dynamic content-aware weights. This allows the system to preserve edges in critical regions while maintaining computational efficiency in smooth areas.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies different interpolation strategies to different local regions of the image based on their characteristics. Edge-directed filtering is applied specifically to regions containing edges and textures, while simpler filtering is used in smooth regions. This local differentiation resolves the contradiction by applying complexity only where necessary for edge preservation.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If bi-cubic interpolation is used to up-sample images, then edge details are better preserved, but visible artifacts and distortion are introduced

Engineering Contradiction:
Improveedge detail preservationVSAvoidvisible artifacts
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent dynamically changes interpolation parameters based on local image content analysis. Instead of using fixed bi-cubic weights, the algorithm adjusts filtering parameters according to detected edge orientations and local variance. This adaptive parameter adjustment preserves edge details while avoiding the artifacts that result from applying uniform complex filtering across the entire image.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from static interpolation parameters to dynamic, content-adaptive parameters. The filtering behavior changes based on real-time analysis of local image characteristics such as edge detection results and texture complexity. This dynamic adaptation eliminates the harmful artifacts produced by rigid bi-cubic interpolation while maintaining edge sharpness.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If spatially invariant interpolation weights are used, then computational simplicity is maintained, but fast-changing local characteristics are not captured

Engineering Contradiction:
Improvecomputational simplicityVSAvoidlocal characteristic adaptation
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent replaces spatially invariant weights with spatially variant weights that adapt to local image characteristics. The algorithm analyzes local regions for edges, textures, and smooth areas, then applies appropriate filtering weights specific to each region. This local adaptation captures fast-changing characteristics while maintaining computational feasibility through efficient algorithms.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamic weight adjustment based on local image content. The interpolation weights are not fixed but are computed or selected based on real-time analysis of edge directions, local variance, and texture characteristics. This dynamic approach enables the system to adapt to fast-changing local characteristics while using efficient algorithms to maintain computational simplicity.

Inventive Principle:
Principle #15Dynamics

4Productivity

If simple area averaging is used for interpolation, then computational speed is improved, but perceptual quality deteriorates with blurring

Engineering Contradiction:
Improvecomputational speedVSAvoidperceptual quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies different levels of filtering complexity to different local regions based on their perceptual importance. Edge regions receive directional filtering that preserves sharpness, while smooth regions use simpler averaging. This local differentiation maintains computational speed by avoiding complex filtering everywhere while improving perceptual quality in critical edge regions where it matters most.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts filtering strength and type based on local edge detection and variance analysis. In regions with high edge content, the algorithm applies stronger edge-preserving filters, while in smooth regions it uses lighter filtering to maintain speed. This dynamic adaptation improves perceptual quality without sacrificing computational efficiency.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS9462220B2Auto-regressive edge-directed interpolation with backward projection constraint
Publication Date: 2016.10.04 MICROSOFT TECHNOLOGY LICENSING LLC
  • US9462220B2 patent drawing
  • US9462220B2 patent drawing
  • US9462220B2 patent drawing

AI summary

Techniques and tools for interpolation of image/video content are described. For example, a tool such as a display processing module in a computing device receives pixel values of a low-resolution picture and determines an interpolated pixel value between a set of the pixel values from the low-resolution picture. The tool uses auto-regressive edge-directed interpolation that incorporates a backward projection constraint (AR-EDIBC). As part of the AR-EDIBC, the tool can compute auto-regressive (AR) coefficients then apply the AR coefficients to the set of pixel values to determine the interpolated pixel value. For the backward projection constraint, the tool accounts for effects of projecting interpolated pixel values back to the pixel values of the low-resolution picture. The tool stores the interpolated pixel values and pixel values from the low-resolution picture as part of a high-resolution picture. The tool can adaptively use AR-EDIBC depending on content and other factors.