JPEG Standard

JPEG standard 

JPEG: “Joint Photographic Experts Group”

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Formally:

ISO/IEC JTC1/SC29/WG10

International Organization for Standardization International Electrotechnical Commission

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Working Group 10 (JBIG, JPEG) Joint ISO/IEC Technical Committee (Information Technology)

Subcommittee 29 (Coding of Audio, Picture, Multimedia and Hypermedia Information)

Joint effort with CCITT (International Telephone and Telegraph Consultative Committee, now ITU-T) Study Group VIII Work commenced in 1986 International standard ISO/IEC 10918-1 and CCITT Rec. T.81 in 1992 Widely used for image exchange, WWW, and digital photography Motion-JPEG is de facto standard for digital video editing Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 1

JPEG: image partition into 8x8 block

8x8 blocks

Padding of right boundary blocks

Padding of lower boundary blocks Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 2

Baseline JPEG coder DC Huffman tables dc quantization indices

input image

Level offset

8x8 DCT

Uniform scalar quantization

Differential coding

Zig-zag scan

Run-level coding

VLC

Compressed image data

VLC

ac quantization indices

Quantization tables

Bernd Girod: EE398A Image and Video Compression

Compressed image data

AC Huffman tables

JPEG standard no. 3

Recommended quantization tables  

Based on psychovisual threshold experiments Luminance  Chrominance, subsampled 2:1 16 12 14 14 18 24 49 72

11 12 13 17 22 36 64 92

10 14 16 22 37 55 78 95

16 19 24 29 56 64 87 98

24 26 40 51 68 81 103 112

40 58 57 87 109 104 121 100

51 60 69 80 103 113 120 103

61 55 56 62 77 92 101 99

17 18 24 47 99 99 99 99

18 21 26 66 99 99 99 99

24 26 56 99 99 99 99 99

47 66 99 99 99 99 99 99

99 99 99 99 99 99 99 99

99 99 99 99 99 99 99 99

99 99 99 99 99 99 99 99

99 99 99 99 99 99 99 99

[JPEG Standard, Annex K] Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 4

intensity

contrast sensitivity (@ 500 cd/m2)

Contrast sensitivity of human vision

position spatial frequency (cpd)

Bernd Girod: EE398A Image and Video Compression

L2  L1 contrast ratio L2  L1 JPEG standard no. 5

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 6

Differential coding of DC coefficients

Q

DC coefficients

+ -

VLC

VL Decoder

One-block delay

+

Q-1

+ One-block delay

Encoder

Decoder

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 7

DC difference categories

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 8

Suggested Huffman code for DC differences JPEG Standard, Table K3 - Luminance

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 9

JPEG run-level coding 

RRRR – four bits value specifying ac coefficient zero-run of length 0…15

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SSSS – four bits specifying a range of magnitudes of the following coefficient (“category”)

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Joint Huffman encoding for 8-bit value RRRRSSSS Append bits for sign and exact magnitude

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 10

JPEG coefficient coding categories

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 11

JPEG suggested AC code for luminance

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 12

JPEG suggested AC code for luminance (cont.)

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 13

AC coefficient probabilities Test image Lena Default quantization matrix

• PMF decays more rapidly for larger run lengths • Almost independent of bitrate (except EOB)

[Kingsbury, 2006] Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 14

AC coefficient probabilities (cont.) Test image Lena Default quantization matrix

• PMF decays more rapidly for larger run lengths • Almost independent of bitrate (except EOB)

[Kingsbury, 2006] Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 15

JPEG compression results

231 kb, uncompressed, 320x240x3x8 bit Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 16

JPEG compression results

74 kb, compressed 3.24:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 17

JPEG compression results

51 kb, compressed 4.53:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 18

JPEG compression results

38 kb, compressed 6.08:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 19

JPEG compression results

31 kb, compressed 7.45:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 20

JPEG compression results

26 kb, compressed 8.88:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 21

JPEG compression results

22 kb, compressed 10.5:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 22

JPEG compression results

21 kb, compressed 11:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 23

JPEG compression results

18 kb, compressed 12.83:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 24

JPEG compression results

17 kb, compressed 13.59:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 25

JPEG compression results

15 kb, compressed 15.4:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 26

JPEG compression results

13 kb, compressed 17.77:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 27

JPEG compression results

11 kb, compressed 21:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 28

JPEG compression results

11 kb, compressed 21:1 Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 29

Beyond Baseline JPEG 

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Huffman code tables can be optionally replaced by arithmetic coder (rarely supported) Hierarchical mode for progressive image transmission No predefined color spaces: up to 255 image components Lossless mode: prediction with Huffman coding of residual (not to be confused with JPEG-LS) Additional information (e.g. date/time, camera, exposure, aperture etc.) may be embedded into JPEG file (e.g., EXIF, DCF used by digital cameras)

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 30

Reading  

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Taubman, Marcellin, Chapter 19 G. K. Wallace, “The JPEG still picture compression standard,” IEEE Trans. Consumer Electronics, vol. 38, no. 1, pp. xviii-xxxiv, Feb. 1992. ITU-T Rec. T.81

Bernd Girod: EE398A Image and Video Compression

JPEG standard no. 31