A fuzzy video content representation for video summarization and content-based retrieval Anastasios D. Doulamis, Nikolaos D. Doulamis, Stefanos D. Kollias.

A fuzzy video content representation for video summarization and content-based

retrieval

Anastasios D. Doulamis, Nikolaos D. Doulamis, Stefanos D. Kollias

2000

Presented by Mohammed S. Al-Logmani

Agenda• Introduction

• Motivation/ Problem Statement

• Video Sequence Analysis

• Fuzzy Visual Content Representation

• Video Summarization

• Content-Based Retrieval

• Experimental Results

• Future Work

• Conclusion

Introduction• The increase amount of digital image &

video data requires new technologies for efficient searching, indexing, content-based retrieving & managing multimedia databases.

• Drawbacks with keyword annotations:• Large amount of effort for developing them.• Cannot efficiently characterize the rich visual

content using only text

Introduction Cont.

• Content-based algorithms• QBIC• VisualSeek• Virage

• Cannot easily applied to video DBs.• Perform queries on every frame is inefficient & time

consuming• Videos DBs. are distributed which impose large

storage & transmission requirements

Introduction Cont.

• Content-based sampling algorithms• Extract small but meaningful info. (summarization)

• Require a more meaningful representation of visual content than the traditional pixel-based one

• Related Work:• A hidden Markov model for color image retrieval

• An approach of image retrieval based on user sketches

• A hierarchical color clustering method

• Construction of a compact image map or image mosaics for video summarization

• A pictorial summary of video sequences based on story units

Motivation/ Problem Statement• Increase the flexibility of content-based

retrieval systems• Provide an interpretation closer to the human

perception

• Result a more robust description of visual content• possible instabilities of the segmentation are

reduced

fuzzy representation of visual content

• Video summarization• Performed by minimizing a cross correlation criterion

among the video frames using a GA.• The correlation is computed using several features

extracted using a color/ motion segmentation on a fuzzy feature vector formulation basis.

• Content-based indexing & retrieval• The user provides queries (images or sketches) which are

analyzed in the same way as video frames in video summarization scheme.

• A metric distance or similarity measure is then used to find a set of frames that best match the user's query.

Video Sequence Analysis• A color/motion segmentation algorithm is

applied for visual content description• Multiresolution Recursive Shortest Spanning

Tree (M-RSST)• recursively applies the RSST to images of increasing

resolution. (a truncated image pyramid is created)

• Produces same results as RSST with less time.

• Eliminates regions of small segments

• Factors affect the segmentation efficiency• The initial image resolution level

• selected to be 3 (downsampling by 8x8 pixels)

• The selection of threshold used for terminating the algorithm

• Euclidean distance of the color or motion intensities between two neighboring segments

• Terminate the segmentation if no segments are merged from one step to another.

Video Sequence Analysis cont.

Video Sequence Analysis cont.

Fuzzy visual content representation

• The size & location cannot be used directly• segments # is not constant for each video frame

• To overcome this problem, pre-determined classes of color/motion properties

• To avoid the possibility of classifying two similar segments to different classes, a degree of membership is allocated to each class• Resulting in a fuzzy classification formulation

• Create a fuzzy multidimensional histogram

Fuzzy visual content representation Cont.

•Example: property (s) is used for each segment.•s takes values in [0,1]•It is classified into Q classes using Q membership functions• • degree of membership of s in the nth class

•Assume a video frame consists of K segments•First, evaluate the degree of membership of feature

si = 1,2, … K, of the ith segment•Then, find the degree of membership of K in the nth class through the fuzzy histogram

Fuzzy visual content representation Cont.

Video summarization

Video summarization Cont.

• Extraction of key-frames• Key-frames are extracted by minimizing a cross-

correlation criterion, so that the selected frames are not similar to each other.

• The generic approach (GA)• Similarities to the traveling salesman problem (TSP).• Initially, a population of m chromosomes is created.• Evaluate the performance of all chromosomes in

population P(n) using a correlation measure.• Evaluate the chromosomes quality using fitness functions.• Select appropriate parent so that a fitter chromosome gives

a higher number of offspring• The GA terminates when the best chromosome fitness

remains constant for a large number of generations

• Examined about170 shot, # Kf=6 , Q=3

Video summarization Cont.

Content-based retrieval• Apply the previous scheme to discard all the

redundant temporal video information• The user can submit:

• Images (query by example)• Sketches (query by sketch)

• Analyze the query using M-RSST• Extract and classify the segments

• Apply a distance similarity measure

Experimental results

Experimental results Cont.

Experimental results Cont.

Future Work• Increase the system accuracy by

developing a fuzzy adaptive mechanism for estimating the distance weights.

Conclusion• Presented a fuzzy video content representation

• Efficient for:• Video summarization• Content-based image indexing & retrieval

• Experimental results indicate that this approach outperforms the other methods for both accuracy and computational efficiency