Video Summarization Ppt

7/31/2019 Video Summarization Ppt

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Video summarization as the name implies, is a short

summary of the content of a longer video

The purpose of video summarization is to extract froma video, a limited number of key frames that convey themeaning of the whole video at a glance.

This project proposes to formulate videosummarization as a search problem and to use Genetic

Algorithms as the search algorithm.


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Genetic algorithms belong to the class of

evolutionary algorithms (EA), which generate

solutions for problems using techniques

inspired by natural evolution, such asinheritance, mutation, selection, and crossover.


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An original video consists of the following

components- Scenes, Shots and frames, in a

hierarchical order

The original video is split up into scenes and then to

shots which finally give frames.

In the video summarization process, only the frames

are considered. A group of selected frames are

combined together to form candidate summaries.


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Selection/Crossover/Mutation

Candidate Summaries

User

Summarized Video

Original Video

Scenes

Shots

Frames


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This forms the first step of thevideo summarization process

where the whole video is split upinto frames


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Defining the population size (CandidateSummaries)

User analysis of the generated summaries by givinga score to each of them

Generating the next set of summaries through theGA procedures of crossover and mutation, basedon the user given scores

Iterating the process until a preferable summary isobtained
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A text field is associated with each of the candidate summarieswhere the user can rate the summary by giving it a score of hischoice.

It is assumed that the one with the highest score forms the most

optimal summary.

This experimentation was carried out with four candidatesummaries. Four corresponding scores are given for each of the fourcandidate summaries.

The algorithm proceeds in such a way that top three scores aretaken and the summary with the highest score is crossed over andmutated with the other two to form a new set of candidate

summaries.


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The GA proceeds through the following stages

Selection Crossover Mutation

The population size is fixed as 4

Based on the user scores for each of thesummaries, the highest 3 scores are selectedand the last one is ignored

The crossover and mutation operations areperformed based on these 3 scores to generatethe next set of summaries

The mutation and crossover probabilities arerandomly generated and a threshold is set,above which mutation and crossover happens


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Once the scores are generated, the summaries are

processed by the genetic algorithm based on the

following two factors:

Crossover

Mutation


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Crossover is a genetic operator

It is analogous to reproduction and biological crossover,upon which genetic algorithms are based.

The first and the second summaries are taken and they are

combined together so that the frames of both the summariesare arranged in the temporal order.

Two new summaries are generated from this combinationsuch that the new summaries will have the alternate values

of the combination, i.e. the first value of the combinationgoes to the first summary, and second value goes to thesecond summary and so on.


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84 128 297199

32 117 312176

32 84 128117 176 199 312297

32 117 297176

84 128 312199


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Mutation is a genetic operator used to maintain geneticdiversity from one generation of a population of algorithm

chromosomes to the next. It is analogous to biologicalmutation.

The purpose of mutation in GAs is to prevent the

population of chromosomes from becoming too similar toeach other, thus slowing or even stopping evolution. Thisexperiment implements mutation after the crossover.

After the generation of a new set of summaries after

crossover, the elements in it are mutated, i.e. values withinare replaced by a new set of values and are arranged in thetemporal order to preserve the semantics.


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Video surveillance: In surveillance video, instead of

viewing the whole video summary of video can be of

use.

Internet: In internet, before downloading a full video,

download the summary video and check if the video is

relevant or not in that case download the video

In movie trailers

In cricket highlights etc


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Video Summarization Ppt

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