Arithmetic-Context Compression

Irina Bocharova, Kirill Yurkov,Mikhail Bogdanov, Roman Bolshakov, Alexander Buslaev,

Yuri Konoplev, Anrew Tereskin, Oleg Finkelshteyn

autumn 2010 - spring 2011

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Agenda

Purpose

Schemes of Encoder and decoder

Encoding DC

Encoding RUN’s and AC

Arithmetic Levenstein codec

Results

Problems

Map of boundary blocks

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Purpose

Realize a recoder of JPEG to reduce bit stream

Requirements: bit-to-bit corrsepondense

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Scheme of encoder

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Scheme of decoder

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Encoding DC (DC Prediction)

B

A

C

X?

?

P =

{

DCC , |DCB − DCA| < |DCB − DCC |

DCA, otherwise

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Encoding Run-lengths and AC (1)

here about RUN’s

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Encoding Run-lengths and AC (2)

and AC

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Arithmetic coding

Arith + Adaptive model

reference

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Levenstein code

Only Levenstein

reference

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Test images

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Result and Comparing

Picture.jpg Size PackJpg We (theory) We (practice)

A10 842 Kb 19.2 % 10.8 %

Afisha 213 Kb

Bird 82 Kb 17.7 % 16.8 %

Document 103 Kb 29.7 % 13.7 %

Flower 5 Kb

Monkey 30 Kb 30.5 % 26.8 %

Portrait 63 Kb

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Problems (1)

problem with parsing and bit-to-bit corrsepondense

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Problems (2)

problem with Arithmetic codec and Alphabet size

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Map of boundary blocks

Is it really necessary?

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Thanks

Questions ?

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References

links array

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