Adding domain specific knowledge
Sponsored Links
This presentation is the property of its rightful owner.
1 / 21

Adding Domain-Specific Knowledge PowerPoint PPT Presentation


  • 62 Views
  • Uploaded on
  • Presentation posted in: General

Adding Domain-Specific Knowledge. Amit Singhal & Jiebo Luo Research Laboratories Eastman Kodak Company FUSION 2001, Montreal August 7-10, 2001. Outline of Talk. Problem Statement Background Relevant Prior Art Evidence Fusion Framework Automatic Main Subject Detection System

Download Presentation

Adding Domain-Specific Knowledge

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Adding Domain-Specific Knowledge

Amit Singhal & Jiebo Luo

Research Laboratories

Eastman Kodak Company

FUSION 2001, Montreal

August 7-10, 2001


Outline of Talk

  • Problem Statement

  • Background

    • Relevant Prior Art

    • Evidence Fusion Framework

    • Automatic Main Subject Detection System

  • Injecting Orientation Information

    • Feature detectors

  • Conclusions

  • Future Work


Main Subject Detection

  • What Is the Main Subject in A Picture?

    • 1st-party truth (the photographer): in general not available due to the specific knowledge the photographer may have about the setting

    • 3rd-party truth: in general there is good agreement among 3rd-party observers if the photographer successfully used the picture to communicate his interest in the main subject to the viewers


Related Prior Art

  • Main subject (region-of-interest) detection

    • Milanese (1993) : Uses biologically motivated models for identifying regions of interest in simple pictures containing highly contrasting foreground and background.

    • Marichal (et al.) (1996), Zhao (et al.) (1996) : Use a subjective fuzzy modeling approach to describe semantic interest in video sequences (primarily video-conferencing).

    • Syeda-Mahmood (1998) : Uses a color-based approach to isolate regions in an image likely to belong to the same object. Main application is reduction of search space for object recognition

  • Evidence Fusion

    • Pearl (1988) :Provides a theory and evidence propagation scheme for Bayesian networks.

    • Rimey & Brown (1994) : Use Bayesian networks for control of selective perception in a structured spatial scene.

    • Buxton (et al.) (1998) : Use a set of Bayesian networks to integrate sensor information to infer behaviors in a traffic monitoring application.


The Evidence Fusion Framework

  • Region based representation scheme.

  • Virtual belief sensors map output of physical sensors and algorithmic feature detectors to probabilistic space.

  • Domain knowledge used to generate network structure.

  • Expert knowledge and ground truth-based training methodologies to generate the priors and the conditional probability matrices.

  • Bayesian network combines evidence generated by the sensors and feature detectors using a very fast message passing scheme.


Bayesian Networks

  • A directed acyclic graph

  • Each node represents an entity (random variable) in the domain

  • Each link represents a causality relationship and connects two nodes in the network

  • The direction of the link represents the direction of causality

  • Each link encodes the conditional probability between the parent and child nodes

  • Evaluation of the Bayes network is equivalent to knowing the joint probability distribution


Automatic Main Subject Detection System

  • An Interesting Research Problem

    • Conventional wisdom (or how a human performs such a task)

      • Object Segmentation -> Object Recognition -> Main Subject Determination

      • Object recognition is an unconstrained problem in consumer photographs

    • Inherent Ambiguity

      • 3rd party probabilistic ground truth

      • Large number of camera sensors and feature detectors

    • Speed and performance scalability concerns

  • Of extreme industrial interest to digital photofinishing

    • Allows for automatic image enhancements to produce better photographic prints

    • Other applications such as

      • Image compression, storage, and transmission

      • Automatic image recompositing

      • Object-based image indexing and retrieval


Overview

  • Methodology

    • Produce a belief map of regions in the scene being part of the main subject

    • Utilize a region-based representation of the image derived from image segmentation and perceptual grouping

    • Utilize semantic features (human flesh and face, sky, grass) and general saliency features (color, texture, shape and geometric features)

    • Utilize a Bayes Net-based architecture for knowledge representation and evidence inference

  • Dealing with Intrinsic Ambiguity

    • Ground truth is “probabilistic” not “deterministic”

    • Limitations in our understanding of the problem

  • Dealing with “Weak” Vision Features

    • Reality of the state-of-the-art of computer vision

    • Limited accuracy of the current feature extraction algorithms


The Multilevel Bayesian Network


Injecting Metadata into the System

  • Sources of metadata

    • Camera : Flash fired, Subject distance, Orientation etc.

    • IU Algorithms : Indoor/Outdoor, Scene type, Orientation etc.

    • User annotation

  • The Bayesian network is very flexible and can be quickly adapted to take advantage of available metadata

  • Metadata enabled knowledge can be injected into the system using

    • Metadata-aware feature detectors

    • Metadata-enhanced Bayesian networks


Orientation

  • Main difference between orientation-aware and orientation non-aware systems is in the location features


The Centrality Feature Detector


Orientation Unaware Centrality Feature Detector


Orientation Aware Centrality Feature Detector


Borderness Feature

  • Orientation Unaware

    • a=b=c=d=e

  • Orientation Aware

    • a < b < c < d < e


Orientation Aware Bayesian Network

  • Use orientation aware centrality and borderness features

  • Other feature detectors affected by orientation but not retrained:

    • sky, grass

      • Not retrained if BN is used for main subject detection as the location features would account for the orientation information

      • Using orientation information to compute the sky and grass evidence would lead to better performance for a sky or grass detection system.

  • Retrain the links in the Bayesian network for each feature affected by orientation information

    • BorderA-Borderness

    • BorderD-Borderness

    • Borderness-Location

    • Centrality-Location

    • Location-MainSubject


Experimental Results


Experimental Results


Experimental Results


dKS Plot of Orientation-Aware MSD


Conclusions and Future Work

  • Bayesian networks offer the flexibility of easily incorporating domain specific knowledge such as orientation information into the system

  • This knowledge can be added by :

    • modifying the feature detectors

    • using new feature detectors

    • changing the structure of the Bayesian network

    • retraining the conditional probability matrices associated with the Bayesian network

  • Directions for Future Work

    • Use of additional metadata such as indoor/outdoor, urban/rural, day/night

    • Single super BN versus a library of metadata-aware BNs?


  • Login