stk.ucoz. viewСОДЕРЖАНИЕ. ВВЕДЕНИЕ. 1. Компрессия (сжатие) данных, техника и типы. 1.1 Краткий обзор понятий

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1. () , .

1.1 .

1.2 / .

1.3 .

1.3.1 .

1.3.2 .

1.4 .

1.4.1 .

1.4.2 .

2. ( ).

2.1 - (LZ*).

2.1.1 .

2.1.2 .

2.1.3 .

2.1.4 LZ78.

2.2 (LZW).

2.2.1 .

2.2.2 .

2.2.3 .

2.2.4 .

2.2.5 .

2.2.6 .

2.2.7 Unisys, GIF PNG.

2.3 .

2.4 -.

2.5 -.

2.6 .

3. .

3.1 .

3.2 .

3.3 JPEG.

4. .

- . , , . -, ( , , ..), -, (- , , ). , . , . , . , , .

, . , - ( , , , ). . , , , .

.

1. () .

1.1 .

, . .

( ) ( ). . , - , .

, . (, ). (). , , , ( ). , (, ), . , .

1.2 / .

2 .

( , ), , . , .

. . , .

1.3 .

, , , - . , . . .

1.3.1 .

:

1) , , . .

2) / , . , , .

, .

1.3.2 .

1) :

JPEG

JPEG 2000

DjVu

2) :

Flash ( JPEG)

H.261

H.263

H.264/MPEG-4 AVC

MNG ( JPEG)

Motion JPEG

MPEG-1 Part 2

MPEG-2 Part 2

MPEG-4 Part 2

Ogg Theora ( )

Sorenson video codec

VC-1 Microsoft WMV

3) :

MP3 MPEG-1

Ogg Vorbis ( [1])

AAC, AAC+ , MPEG-2 MPEG-4, , , Apple Computer

eAAC+ , Sony, AAC AAC+

Musepack

WMA Microsoft

ADPCM

ATRAC

Dolby AC-3

DTS

MP2

VQF

4)

CELP

G.711

G.726

HILN

Speex ( )

1.4 .

(. Lossless data compression) , . . . , , .

. , ZIP Unix- Gzip. .

, . . , PNG GIF, ; (TIFF, MNG) , .

1.4.1 .

, . , . , ( , ) , . , , .

: , , ( ) , , . , , ( , . .) .

( , ) :

(- -, )

LZ77 LZ78 ( DEFLATE)

LZW

:

( DEFLATE)

1.4.2 .

1) :

, ,

LZW gif

Deflate gzip, zip PNG

2) :

Apple Lossless ALAC (Apple Lossless Audio Codec)

Audio Lossless Coding MPEG-4 ALS

Direct Stream Transfer DST

Dolby TrueHD

DTS-HD Master Audio

Free Lossless Audio Codec FLAC

Meridian Lossless Packing MLP

Monkey's Audio Monkeys Audio APE

OptimFROG

RealPlayer RealAudio Lossless

Shorten SHN

TTA True Audio Lossless

WavPack WavPack lossless

WMA Lossless Windows Media Lossless

3) :

ABO Adaptive Binary Optimization

GIF ( , )

JBIG2 ( / )

JPEG-LS ( / )

JPEG 2000 ( ; , Sunil Kumar, -)

PGF Progressive Graphics File ( / )

PNG Portable Network Graphics

Qbit Lossless Codec intra-frame ( )

TIFF

WMPhoto ( )

4) :

Animation codec

CamStudio Video Codec

CorePNG

FFV1

H.264/MPEG-4 AVC

Lagarith

LCL

MSU Lossless Video Codec

Qbit Lossless Codec

SheerVideo

TSCC TechSmith Screen Capture Codec

:

-

RLE (Run-length encoding )

:

Zip, 7-Zip, RAR, GZip, PAQ .

FLAC (Free Lossless Audio Codec), Monkeys Audio (APE), TTA (True Audio), TTE, LA (LosslessAudio), RealAudio Lossless, WavPack .

BMP, GIF, PNG

Huffyuv.

2. ( ).

. -, Stacker Doublespace .., .

, , , . , , , . ", ".

. (., ) . , - . . . .

, (., -). , ( ). . , . 2-32 , 400 .

: . . (, TCP/IP DECnet). , (., X.25 PPP), . .

, . , 4 . , ( ) , .

, , (RFC-1144). 64 K/. 50% 4800 /. . , . , , SMDS (Switched Multi-megabit Data Service), ATM, X.25 Frame Relay. -, - / , . , .

. , . , , -. , , /. , , .

, , . , . X.25, SMDS, Frame Relay ATM. CISCO / , .

, , . -.

2.1 - (LZ*).

1977 , LZ77. compress , lha , pkzip arj . , LZ* , RLE. : .

2.1.1 .

, , ( ).

LZ* . ( ), , . , LZ77 , , . 2 , 4 32 . , , .

, LZ77 . , LZ77 , .

2.1.2 .

, , ( . match). N . , , , , .

LZ77 :

(match length)

(offset) ( (distance))

, , LZ77, , : , .

, , , LZ77 . , - , , .

: 1 7 , . 7 , 1 ? : 7 () 1 . , , -. ( ) ( ) , RLE.

2.1.3 .

, ,

, ,

2.1.4 LZ78.

LZ77, , LZ78 , (LZ78 "" , ). , . , , , , , . . , .

2.2 (LZW).

(Lempel-Ziv-Welch, LZW) , (Abraham Lempel), (Jacob Ziv) (Terry Welch). 1984 , LZ78, 1978 . , , , .

LZW : , , , , , .

() : () ( 12-). 1- ( 8- 256 ). , , , 2- /, . 2- , . , , ; , .

, .

2.2.1 .

1) . w .

2) K .

3) _, w,

wK , wK 2, w, wK , K 2.

2.2.2 .

LZW , , . .

compress, - Unix- 1986 . - .

1987 GIF. () TIFF.

, Adobe Acrobat.

2.2.3 .

LZW , , , . , , . , , :

TOBEORNOTTOBEORTOBEORNOT#

# . , 27 (26 #). , 5- . , , . 5- 25 = 32 , , 33- , 6- . , , 00000, 33- 32. :

# = 00000

A = 00001

B = 00010

C = 00011

.

.

.

Z = 11010

2.2.4 .

LZW, 25 5 125 . , LZW:

: : :

( )

T 20 = 10100

O 15 = 01111 28: TO

B 2 = 00010 29: OB

E 5 = 00101 30: BE

O 15 = 01111 31: EO

R 18 = 010010 32: OR