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A Review of Data Compression Techniques Presented by Sudeepta Mishra Roll# CS200117052 At NIST,Berhampur Under the guidance of Mr. Rowdra Ghatak

Introduction ,[object Object],[object Object]

Different Compression Techniques ,[object Object],[object Object],[object Object],[object Object],[object Object]

Types of Loss less data Compression ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Dictionary-Based Compression ,[object Object],[object Object],[object Object]

Types of Dictionary ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Dictionary-Based Compression: Example

Lempel Ziv ,[object Object],LZ77 LZ78 LZR LZH LZSS LZB LZFG LZC LZT LZMW LZW LZJ

LZW Algorithm ,[object Object],[object Object],[object Object]

The LZW Algorithm (Compression) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The LZW Algorithm (Compression) Flow Chart START W= NULL IS EOF ? K=NEXT INPUT IS WK FOUND? W=WK OUTPUT INDEX OF W ADD WK TO DICTIONARY STOP W=K YES NO YES NO

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],a b d c a d a c a 1 b 2 c 3 d 4

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],K a b d c a d a c a 1 b 2 c 3 d 4

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],K a b d c a d a c 1 ab 5 a 1 b 2 c 3 d 4

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],K a b d c a d a c 1 2 ab 5 a 1 b 2 c 3 d 4 bd 6

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],K a b d a b d a c 1 2 4 ab 5 a 1 b 2 c 3 d 4 bd 6 da 7

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],K a b d a b d a c 1 2 4 ab 5 a 1 b 2 c 3 d 4 bd 6 da 7

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],K a b d a b d a c 1 2 4 5 ab 5 a 1 b 2 c 3 d 4 bd 6 da 7 abd 8

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],K a b d a b d a c 1 2 4 5 ab 5 a 1 b 2 c 3 d 4 bd 6 da 7 abd 8

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],K a b d a b d a c 1 2 4 5 ab 5 a 1 b 2 c 3 d 4 bd 6 da 7 abd 8 7 dac 9

The LZW Algorithm (Compression) Example ,[object Object],[object Object],[object Object],K c a d b a d b a 1 2 4 5 5 ab 4 d 3 c 2 b 1 a 6 bd 7 da 8 abd 7 9 dac 3

LZW Decompression Algorithm read a character k; output k; w = k; while ( read a character k ) /* k could be a character or a code. */ { entry = dictionary entry for k; output entry; add w + entry[0] to dictionary; w = entry; }

LZW Decompression Algorithm Flow Chart START Output K IS EOF ? K=NEXT INPUT ENTRY=DICTIONARY INDEX (K) ADD W+ENTRY[0] TO DICTIONARY STOP W=ENTRY K=INPUT W=K YES NO Output ENTRY

The LZW Algorithm (Decompression) Example ,[object Object],[object Object],[object Object],K 1 2 4 5 4 d 3 c 2 b 1 a 7 3 a

The LZW Algorithm (Decompression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],K 1 2 4 5 4 d 3 c 2 b 1 a 7 3 a b 5 ab

The LZW Algorithm (Decompression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],K 1 2 4 5 4 d 3 c 2 b 1 a 7 3 a b 5 ab 6 bd d

The LZW Algorithm (Decompression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],K 1 2 4 5 4 d 3 c 2 b 1 a 7 3 a b 5 ab 6 bd d a b 7 da

The LZW Algorithm (Decompression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],K 1 2 4 5 4 d 3 c 2 b 1 a 7 3 a b 5 ab 6 bd d a b 7 da d a 8 abd

The LZW Algorithm (Decompression) Example ,[object Object],[object Object],[object Object],[object Object],[object Object],K 1 2 4 5 4 d 3 c 2 b 1 a 7 3 a b 5 ab 6 bd d a b 7 da d a 8 abd c 9 dac

Advantages ,[object Object],[object Object],[object Object]

Problems with the encoder ,[object Object],[object Object],[object Object]

Conclusion ,[object Object],[object Object],[object Object]

REFERENCES ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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