Navidgator. Similarity Based Browsing for Image & Video Databases. Damian Borth, Christian Schulze, Adrian Ulges, Thomas M. Breuel

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1 Navidgator Similarity Based Browsing for Image & Video Databases Damian Borth, Christian Schulze, Adrian Ulges, Thomas M. Breuel Image Understanding and Pattern Recognition DFKI & TU Kaiserslautern 25.Sep.2008 Borth: KI Sep.2008

2 Outline Borth: KI Sep.2008

3 Motivation How to retrieve & browse in large databases of images or videos? I I I Movie scene finder provide global view browse through all images of last year find scenes of Batcave form The Dark Knight I TV network archives find visual similar images find all pictures with a beach Borth: KI2008 need a desert video clip for news report 3 25.Sep.2008

4 Browsing Metaphor: Stack of images Start Browsing no query is selected a random set of image is displayed user selects image which roughly represents this query Borth: KI Sep.2008

5 Browsing Metaphor: Stack of images Zooming & Panning zooms into the database i.r.t. selected query displays a more detailed cluster of images panning = refinement of query further zooms will lead to different results Borth: KI Sep.2008

6 Related Work Query-by-Example [Flickner95] database is searched according to given image tend to provide a localized view of the database How to get an overview? ViBE System [Chen04] browsing based on Similarity Pyramids browsing performed only at shoot level shot = one keyframe loosing visual details Borth: KI Sep.2008

7 Our Approach System Pipeline Keyframe Extraction only for video databases Feature Extraction Balanced Hierarchical Clustering User Interface Borth: KI Sep.2008

8 Keyframe Extraction Notation video database DB video = X 1,..., X n every video X i DB video is represented by a set of {x i1,..., x im } keyframes resulting in a total set of {x 1,..., x k } keyframes for the entire DB video Borth: KI Sep.2008

9 Keyframe Extraction Two Step Method Shot Boundary Detection Color Layout Desc. (CLD) differences Adaptive Thresholding [Lienhart01] Intra-Shot Clustering [Hammoud00] CLD feature space K-Means Number of clusters: Bayesian Information Criterion (BIC) Borth: KI Sep.2008

10 Feature Extraction & Hierarchical Clustering Feature Extraction a feature vector z j R D is extracted for every keyframe x j {x 1,..., x k } z j R D consists of equally weighted color & texture features Color Histograms binning of RGB Cube Tamura Texture Histograms [Tamura78] Borth: KI Sep.2008

11 Feature Extraction & Hierarchical Clustering Feature Extraction a feature vector z j R D is extracted for every keyframe x j {x 1,..., x k } z j R D consists of equally weighted color & texture features Color Histograms binning of RGB Cube Tamura Texture Histograms [Tamura78] Clustering Overview (a) Feature Space of z j R D (c) Dendrogram (b) Clustering Result (d) Generated Binary Tree Borth: KI Sep.2008

12 Balanced Hierarchical Clustering (cont) Agglomerative Hierarchical Clustering 1. initialization: - each feature vector z j {z 1...z k } represents a singelton cluster c j {c 1...c k } - compute Euclidean distance for singeltons 2. merge two nearest clusters: {c i } {c j } {c i, c j } 3. update distances i.r.t. merged clusters 4. go to step 2 until c = 1 Borth: KI Sep.2008

13 Balanced Hierarchical Clustering (cont) Agglomerative Hierarchical Clustering 1. initialization: - each feature vector z j {z 1...z k } represents a singelton cluster c j {c 1...c k } - compute Euclidean distance for singeltons 2. merge two nearest clusters: {c i } {c j } {c i, c j } 3. update distances i.r.t. merged clusters 4. go to step 2 until c = 1 Nearest = Used Linkage Method Singelton Linkage Complete Linkage Average Linkage Borth: KI Sep.2008

14 Balanced Hierarchical Clustering (cont) Average Linkage d(c i, c j ) = 1 c i c j z i c i z j c j d(z i, z j ) distance between means of cluster pairs Borth: KI Sep.2008

15 Balanced Hierarchical Clustering (cont) Average Linkage d(c i, c j ) = 1 c i c j z i c i z j c j d(z i, z j ) distance between means of cluster pairs Clustering Result binary tree is linearized not usable for browsing Borth: KI Sep.2008

16 Balanced Hierarchical Clustering (cont) Modified Average Linkage d(c i, c j ) = 1 c i c j z i c i z j c j d(z i, z j ) + α ( c i + c j ) Balancing Term: α ( c i + c j ), where 0 α empirically gave best results with α = 0.01 Borth: KI Sep.2008

17 Balanced Hierarchical Clustering (cont) Modified Average Linkage d(c i, c j ) = 1 c i c j z i c i z j c j d(z i, z j ) + α ( c i + c j ) Balancing Term: α ( c i + c j ), where 0 α empirically gave best results with α = 0.01 Clustering with Balancing Term balancing term forces clustering to prefer small clusters binary tree is more balanced preferred browsing structure Borth: KI Sep.2008

18 Balanced Hierarchical Clustering (tree building) Binary Tree Generation postprocessing of dendrogram structure into a binary tree neglecting similarity measurement given by dendrogram singelton clusters c i define leafs of binary tree merging points {c i, c j } define inner nodes of binary tree Borth: KI Sep.2008

19 Balanced Hierarchical Clustering (tree building) Question: How to arrange keyframes within a cluster? Elements within a cluster do not have a spatial arrangement Additional processing to provide spatial organization Quad-Tree to Pyramid Mapping [Chen98] Our Approach: Use the already available cluster hierarchy Inorder Traversal of tree structure Borth: KI Sep.2008

20 Navidgator User Interface Borth: KI Sep.2008

21 Navidgator User Interface User Interface 1. Selected Query 2. Similarity Cluster (if query refinement is needed) 3. Navigation Menu 4. Browser History 5. Restart Browsing Borth: KI Sep.2008

22 Live Demo...do we have Internet access here?... (demo also available at the DFKI-IUPR booth) Borth: KI Sep.2008

23 Summary Typical Browsing Scenario annotation (tags) are not always available user has a rough visual concept of the query in mind Navidgator Prototype browsing with query by example paradigm use of dynamic query refinement allows to zoom into different levels of detail Further Work dealing with growing databases online clustering tree merging Borth: KI Sep.2008

24 References [Flickner95]: M. Flickner et al. Query by image and video content: the QBIC system. IEEE Computer Journal, [Lienhart01]: R. Lienhart. Reliable Transition Detection in Videos: A Survey and Practitioner s Guide. IJIG, [Hammoud00]: R. Hammoud, R. Mohr. A Probabilistic Framework of Selecting Effective Key-Frames for Video Browsing and Indexing [Tamura78]: H. Tamura, S. Mori, T. Yamawaki. Textural features corresponding to visual perception. IEEE-SMC, [Chen04]: J.Y. Chen, C. Taskiran, A. Albiol, E.J.Delp, C.A. Bouman. Vibe: A compressed video database structured for active browsing and search, IEEE Transactions on Multimedia [Chen98]: J. Chen, C.A. Bouman, J.C. Dalton. Similarity pyramids for browsing and organization of large image databases, SPIE Borth: KI Sep.2008

25 Questions? Borth: KI Sep.2008