Optical Flow Fusion for Large Motion and Small Object Accuracy

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Solution Overview

Problem

Conventional algorithms for computing nearest neighbor fields between images are computationally expensive and fail to enforce spatial coherency, leading to noisy optical flow estimates and poor performance in handling large motions and small or thin objects.

Innovation Solution

An optical flow with nearest neighbor field fusion method that generates an initial motion field, determines matching patches, and uses region patch matches to account for both small and large displacements, optimizing pixel assignments through an energy function to achieve sub-pixel accuracy and correct motion discontinuities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional exhaustive search is used to compute nearest neighbor fields, then matching accuracy is improved, but computational cost and time consumption increase significantly

Engineering Contradiction:
Improvematching accuracyVSAvoidcomputational efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the image into patches and processes them in a hierarchical manner through multiple levels of an image pyramid. Instead of exhaustively searching all patches at full resolution, the algorithm divides the problem into coarse-to-fine stages, where each level processes smaller regions first and refines results at progressively finer resolutions, significantly reducing computational complexity while maintaining matching accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by first computing optical flow at coarse levels of the image pyramid to establish initial motion estimates. These preliminary results are then used to guide and constrain the exhaustive search at finer levels, so that the computationally expensive precise matching is only performed in relevant regions with reduced search spaces, rather than exhaustively searching the entire image at full resolution from the start.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If conventional optical flow algorithms are used, then spatial coherency is enforced, but they fail to handle large motions between images

Engineering Contradiction:
Improvespatial coherencyVSAvoidhandling large motions
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent employs a dynamic, multi-scale approach using an image pyramid where the analysis resolution adapts to the magnitude of motion. At coarser levels, the algorithm can capture large displacements that would be impossible to detect at fine resolutions. The spatial coherency constraint is dynamically applied at each level, allowing the system to maintain stability for small motions while adapting to handle large motions through the hierarchical structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent adds a dimensional aspect by introducing multiple resolution levels through the image pyramid. Instead of working in a single fixed resolution space, the algorithm operates across multiple scales, transforming the problem from a two-dimensional spatial matching task into a multi-dimensional problem that includes resolution level as an additional dimension. This allows large motions to be captured at coarser levels while maintaining precision at finer levels.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If image pyramid down-sampling is used to handle large motions, then large displacements are accounted for, but small or thin objects are lost or obscured

Engineering Contradiction:
Improvehandling large motionsVSAvoiddetail preservation
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the image processing task across multiple resolution levels, with each level handling different scales of features. Coarse levels capture large-scale motions and structures, while fine levels preserve small details and thin objects. By segmenting the problem this way, the algorithm ensures that small or thin objects are not lost in the down-sampling process, as they are processed and matched at finer resolution levels where their details are preserved.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces the resolution level as an additional dimension, creating a multi-scale processing framework. Instead of losing information through single-level down-sampling, the algorithm maintains information across multiple dimensional levels. Small or thin objects that may be obscured at coarse levels are recovered and properly matched at finer levels, effectively using the resolution dimension to preserve detail information that would otherwise be lost.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Ease of manufacture

If conventional optical flow is initialized to zero everywhere, then the algorithm is simple to implement, but it cannot account for large motion between images

Engineering Contradiction:
Improvealgorithm simplicityVSAvoidhandling large motions
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent performs preliminary action by first computing a coarse-level optical flow field that captures large-scale motions. This preliminary flow estimate is then used to initialize the fine-level optimization, replacing the conventional zero initialization. This preliminary computation at coarse levels provides a head start for handling large motions, while the overall algorithm structure remains relatively simple and builds upon conventional optical flow methods.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent makes the initialization dynamic rather than static. Instead of always initializing to zero, the algorithm dynamically computes an appropriate initialization based on coarse-level analysis. This dynamic initialization adapts to the actual motion magnitude in the image pair, allowing the simple conventional optical flow framework to handle both small and large motions effectively by adjusting its starting point based on the problem characteristics.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS9129399B2Optical flow with nearest neighbor field fusion
Publication Date: 2015.09.08 ADOBE INC
  • US9129399B2 patent drawing
  • US9129399B2 patent drawing
  • US9129399B2 patent drawing

AI summary

In embodiments of optical flow with nearest neighbor field fusion, an initial motion field can be generated based on the apparent motion of objects between digital images, and the initial motion field accounts for small displacements of the object motion. Matching patches of a nearest neighbor field can also be determined for the digital images, where patches of an initial size are compared to determine the matching patches, and the nearest neighbor field accounts for large displacements of the object motion. Additionally, region patch matches can be compared and determined between the digital images, where the region patches are larger than the initial size matching patches. Optimal pixel assignments can then be determined for a fused image representation of the digital images, where the optimal pixel assignments are determined from the initial motion field, the matching patches, and the region patch matches.