Scribble Segmentation Using Weighted Biharmonic Equation

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Solution Overview

Problem

Current image segmentation methods, especially in three dimensions, suffer from the 'shrinking bias' problem, leading to unintuitive and often incorrect segmentations, as automatic methods lack user control and require extensive manual corrections, while semi-automatic methods are time-consuming and difficult to adjust.

Innovation Solution

The use of a weighted biharmonic equation with an algebraic multigrid technique and patch matrices to constrain image element membership values, allowing for more direct user control and improving segmentation accuracy in three dimensions by reformulating the biharmonic equation into a coupled problem and solving it using multigrid methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If automatic segmentation methods are used, then segmentation time is reduced, but user control over the result is relinquished and accuracy deteriorates

Engineering Contradiction:
Improvesegmentation timeVSAvoidsegmentation accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces an energy minimization framework as an intermediary between automatic segmentation and user control. The energy function incorporates both image data fidelity and user-defined constraints, allowing automatic computation while maintaining user oversight. This mediator enables the system to automatically determine segmentation boundaries while respecting user-specified regions of interest.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The segmentation process is made dynamic through iterative energy minimization. The system allows users to progressively add constraints and recompute the segmentation, with the energy function adapting to new constraints. This dynamic approach enables the system to evolve from fully automatic to more user-guided segmentation based on intermediate results.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If manual segmentation methods are used, then user control is maximized, but segmentation time increases significantly

Engineering Contradiction:
Improvesegmentation accuracyVSAvoidsegmentation time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Instead of requiring complete manual segmentation, the system applies partial action by allowing users to specify only critical constraints (e.g., must-be-included and must-be-excluded regions). The energy minimization framework then automatically determines the remaining segmentation, performing just enough manual input to guide the automatic process toward the desired result.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If semi-automatic scribble segmentation is used, then segmentation time is reduced compared to manual methods, but the method becomes difficult to adjust and requires extensive user input

Engineering Contradiction:
Improvesegmentation timeVSAvoidadjustability
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The system implements feedback through iterative energy minimization where users can review intermediate segmentation results and add or modify constraints based on the output. The energy function provides feedback about how well current constraints satisfy the segmentation goals, allowing users to adjust their inputs systematically rather than guessing which constraints to add.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS9105096B2Scribble segmentation method and apparatus
Publication Date: 2015.08.11 ELEKTA AB
  • US9105096B2 patent drawing
  • US9105096B2 patent drawing
  • US9105096B2 patent drawing

AI summary

An apparatus and method of segmenting an image using scribble segmentation is provided. An image is segmented by constraining the membership value of a subset of image elements, solving a weighted biharmonic equation subject to the constrained membership values wherein the weights are determined from similarities between image elements, and determining the final segmentation based on the membership value of each image element. An image may also be segmented by constraining a membership value of a subset of image elements, determining the unknown membership values given the constraints by solving a linear equation system using a multigrid technique, and updating a coarser level of the multigrid hierarchy to account for additional constraints using patch matrices.