Machine learning and multimedia information retrieval

Machine Learning and Multimedia Information Retrieval*

Integrated Knowledge Solutions

iksinc@yahoo.com

* Based on a talk at ICMLA Conference

Outline

• Introduction

• Bridging the Semantic Gap

• Events in Videos

• Use of Tagging in MIR

• Killer Apps of MIR

• Take Home Message

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Too Much Information

Which is more frustrating?

Being stuck in traffic on way to or from work

Not being able to find information you urgently need

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According to a survey by Xerox

Nalanda University was one of the first universities in the world, founded in the 5th Century BC, and reported to have been visited by the Buddha during his lifetime. At its peak, in the 7th century AD, Nalanda held some 10,000 students when it was visited by the Chinese scholar Xuanzang.

Not a New Problem

The Royal Library of Alexandria, in Egypt, seems to have been the largest and most significant great library of the ancient world. It functioned as a major center of scholarship from its construction in the third century B.C. until the Roman conquest of Egypt in 48 B.C.

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However, Earlier

Data Producers

Data Consumers

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But Now a Days

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Some Relevant Numbers

Photobucket has 6.2 billion photos and Flickr has over 2 billion.

Facebook has over 10 Billion photos and over 400 million active users.

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Phenomenon

• 24 hours of videos are uploaded to YouTube every one minute

• YouTube streams 2 billions of videos every day

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So how do we get help in finding the desired multimedia information?

MIR

So What is MIR?

• Also known as CBIR (Content-based Image Retrieval) and CBVIR (Content-based Visual Information Retrieval)

• Deals with systems that manage and facilitate searching for multimedia documents such as images, videos, audio clips and slides etc based on content

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History of MIR

• Conference on Database Applications of Pictorial Applications, 1979 (Florence, Italy)

• NSF Workshop on Visual Information Management Systems, 1992 (Redwood, CA)

• QBIC (Query By Image Content), 1993 (SPIE’s Conf on Storage and Retrieval for Image and Video Databases), Also First ACM Multimedia Conference

• Shift to semantic similarity from signal similarity, 1999

• Community tagging, photo and video sharing sites, 2002

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A Typical MIR System

Feature Extraction

Features Media Collection

Indexing & Matching

Query Feature Extraction

Retrieved Results

Relevance Feedback

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Semantic Gap

Early systems produced results wherein the retrieved documents were visually similar (signal level similar) but not necessarily similar in showing the same semantic concept.

Content-Based Image Retrieval at the End of the Early Years Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence , Arnold Smeulders , Marcel Worring , Simone Santini , Amarnath Gupta , Ramesh Jain , December 2000

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http://www.searchenginejournal.com/7-similarity-based-image-search-engines/8265/

Semantic Gap

Users also like to query using descriptive words rather than query images or other multimedia objects. This requires MIR systems to correlate low-level features with high level concepts.

Visually dissimilar images representing the same concept.

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How to Bridge the Semantic Gap?

Exploit context • Text surrounding images • Associated sound track and closed captions in videos • Query history

Use machine learning to: • Build image category classifiers to perform semantic filtering of the results • Build specific detectors for objects to associate concepts with images •Build object models using low level features

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Exploiting Context: An Example

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Kulesh, Petrushin and Sethi, “The PERSEUS Project: Creating Personalized Multimedia News Portal,” Proceedings Second Int’l Workshop on Multimedia Data Mining, 2001

Example of Using Surrounding Text

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Context via Surrounding Text

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Context Via Surrounding Text: One More Example

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Better Context with More Text

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Improving Context via More Words per Query

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Issues Unique to ML for MIR

• Simultaneous presence of multiple concepts

• How to extract/isolate concept-specific features? Segment or do not segment?

• Imbalance between positive and negative examples

• Extremely large number of concepts for a general purpose MIR

Romance, couple, beach, sundown From: s163.photobucket.com

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A Template Relating Concepts with Pictures Concepts Image Tokens Images

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Feature Extraction Issues

Whole image based features. Easy to use but not very effective

Region based features. Both regular region structure and segmented regions are popular

Salient objects based features. Connected regions corresponding to dominant visual properties of objects in an image

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Scale Invariant Feature Transform (SIFT) Descriptors

SIFT descriptors or its variants are currently the most popular features in use. Each image generates thousands of features (key point descriptors) with each feature typically consisting of 128 values

http://www.vlfeat.org/

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D. G. Lowe, “Distinctive image features from scale-invariant keypoints,” IJCV, 2004.

Feature Discovery

Basic idea is to discover features that are best suitable for a given collection

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Mukhopadhyay, Ma, and Sethi, “Pathfinder Networks for Content Based Image Retrieval Based on Automated Shape Feature Discovery,” ISMSE 2004

Image Category Classifiers (ICC)

• Trained using both supervised and unsupervised learning methods (SVM, DT, AdaBoost, VQ etc)

• Early work limited to few tens of categories; however some of the current systems can work with thousands of categories/concepts

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VQ Based Image Category Classifier

Test Image

Best Codebook Label

Water Codebook

Sky Codebook

Fire Codebook

Mustafa & Sethi (2004)

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Object Detectors

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PASCAL Visual Object Classes Challenge

Project

http://labelme.csail.mit.edu/

Web-based annotation tool to segment and label image regions. Labeled objects in images are used as training images to build object detectors.

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IMARS provides a large number of built-in classifiers for visual categories that cover places, people, objects, settings, activities and events. It is easy to add new ones. IMARS can work on PC or laptop (trial version is available at IBM alphaWorks). IMARS can also work at large-scale for high-volume batch processing of millions and images and videos per day. Several demos of IMARS are available (see IMARS demos)

Image Category Classifiers Examples

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Semantic labeling. (a) An MPE semantic retrieval system groups images by semantic concept and learns a probabilistic model for each concept. (b) The system represents each image by a vector of posterior concept probabilities.

From Pixels to Semantic Spaces: Advances in Content-Based Image Retrieval (Nuno Vasconcelos, IEEE Computer, July 2007)

Image Classification via Probabilistic Modeling

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Retrieving Events in Videos

• An event in MIR implies an interesting spatiotemporal instance

• Considerable work in MIR community on events because of popularity of sports videos

• Also tremendous interest in detecting and recognizing events with potential homeland security applications

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Event Retrieval Examples: Supervised Approach

Mustafa & Sethi AVSS Conference 2005

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Unsupervised Learning for Event Retrieval

Mustafa & Sethi, ICTAI 2007

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Unsupervised Learning Based Event Retrieval

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Mustafa & Sethi, ICTAI 2007

Retrieval By Cross-Modal Associations

Approaches: Latent semantic indexing (LSI) Cross-modal factor analysis (CFA) Canonical correlation analysis (CCA)

- Using query from one modality (e.g. audio) to retrieve content on a different modality (e.g. video) - Directly on low-level features

Li, Dimitrova, Li and Sethi (ACM MM 03) 12/12/2010 37 ICMLA Talk

Talking Face Example

...

Feature

Extraction

Feature

Extraction

Query

Collection

of Image

Sequences

Retrieval Results

Cross-Modal

Association

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M. Li, D. Li, Dimitrova and Sethi, “Audio-Visual Talking Face Detection,” Proceedings, ICME, 2003

Tagging in MIR

All time most popular tags at Flickr

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About Tags

• User centered

• Imprecise and often overly personalized

• Tag distribution follows power law

• Most users use very few distinct tags while a small group of users works with extremely large set of tags

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How are Tags Being Used in MIR?

Relating tags in different languages through visual features

Aurnhammer, Hanappe and Steels Proc. WWW2006

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Tag Suggester

Kucuktunc, Sevil, Tosun, Zitouni, Duygulu, and Can (SAMT 08)

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Collaborative Tags

• Also known as Folksonomy, social tagging, and social classification

• Great for content characterization • The tag size represents the number of times the tag has

been applied to the same item by different users. It kind of represents the level of agreement /confidence in a tag.

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Decision Tree Based Tagger

• Uses social tags in binary/weighted mode

• Generates/suggests multiple tags through a single decision tree classifier

First, the label vectors associated with training vectors are clustered into two initial groups

Next, the SVM is used on training vectors to yield the split that best matches the clustering result

An impurity based measure is used to iteratively adjust the split, if needed

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Ma, Sethi, and Patel. “Multilabel Classification Method for Multimedia Tagging”. (IJMDEM, 2010)

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Current Status of MIR

• Extensive interest as evident from conferences, journals, and special issues

• Most in the MM community happy with the progress

• Gap between published results and results from publicly available systems on web. (http://www.theopavlidis.com/technology/CBIR/PaperB/icpr08.htm)

• Lack of application focus

• Plenty of scope for machine learning to help improve MIR systems performance

• Killer applications are beginning to emerge

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MIR Application Examples

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Tattoo-ID: Automatic Tattoo Image Retrieval for Suspect & Victim Identification (Anil K. Jain, Jung-Eun Lee, and Rong Jin)

Biological and Medical Data Retrieval

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http://www.cs.washington.edu/research/VACE/Multimedia/

Killer Apps?

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http://www.iqengines.com/applications.php

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http://www.iqengines.com/applications.php

http://www.thingd.com

Bloomberg Businessweek, Nov29, 2010 12/12/2010 53 ICMLA Talk

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Take Home Message

• MIR is emerging in the commercial domain. Lot more activity is expected in near future

• MIR community is obsessed with general purpose retrieval engine; a folly pursued by computer vision community for a long time

• ML is playing a vital role in MIR

• Approaches combining social search and visual search techniques are expected to gain prominence

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Acknowledgement

• This presentation is based on the work of numerous researchers from the MIR/ML/CVPR community. I have tried to give credit/references wherever possible. Any omission is unintentional and I apologize for that.

• Also want to thank my present and past students and collaborators.

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Questions?

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