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Advanced JPEG. Dinesh Ganotra. Organizations Involved. Joint Photographic Experts Group ISO International Organization for Standards CCITT International Telegraph and Telephone Consultative Committee IEC International Electro-technical Commission. Recap. Contrast Sensitivity of the Eye.

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Advanced jpeg

Advanced JPEG

DineshGanotra


Organizations involved
Organizations Involved

  • Joint Photographic Experts Group

  • ISO International Organization for Standards

  • CCITT International Telegraph and Telephone Consultative Committee

  • IEC International Electro-technical Commission



Contrast sensitivity of the eye
Contrast Sensitivity of the Eye

  • At a 1 meter viewing distance an ideal digital image 40cm wide should have about 4,000 pixels.

  • The contrast sensitivity curve for luminance is different from chrominance.


Quantization table
Quantization Table

Luminance Quantization Table

Chrominance Quantization Table


Zero shift
ZERO SHIFT

The 8-bit image data is zero-shifted by subtracting 128 from the data before the DCT is calculated. For 12-bit data the zero shift is accomplished by subtracting 2048. This reduces the internal precision requirement for DCT calculation.


DCT

One multiplication and nine additions per coefficient


Entropy
Entropy

001

0

10

11

100

101


lossless

Sequential

DPCM

lossy

Progressive

DCT

Huffman

Arithmetic

Hierarchical


Huffman

Arithmetic

Computationally Simpler

Higher Performance ( 10%)

code book adapts dynamically

to the data being coded.

Requires code tables to be known


Sequential

Progressive

encodes the image in two or more scans or passes through the data, first coding an approximation of the entire image with each succeeding scan.

codes the image in a single scan or passes through the data.

decoder follows the same order in decoding, first reconstructing the approximating of the image, and then adding finer detail with each succeeding scan

The decoder necessarily follows the same order in decoding the data


Progressive

magnitude bit plane

AC band 3

DC band 1

AC band 2

AC band 1

2

1

AC band 4

AC band 5

DC band 4

AC band 6

0

Progressive


Hierarchical
Hierarchical

progressive coding with increasing spatial resolution between progressive stages


Data unit

Y1

Y1

Y2

Y2

Y3

Y4

Cb1

Cb1

Cb2

Cb2

Cr1

Cr1

Cr2

Cr2

Y3

Y5

Y6

Y4

Y7

Y8

Cb3

Cb3

Cb4

Cb4

Cr3

Cr3

Cr4

Cr4

Y5

Y6

Y7

Y8

Data Unit

Vertically interleaved data units

Horizontally interleaved data units


Non interleaved horizontal and vertical interleaved
Non interleaved, horizontal , and vertical interleaved

Scan1 : Y1 , Y2 , Y3 , Y4 , Y5 , Y6 , Y7 , Y8 Scan2 : Cb1 , Cb2 , Cb3 , Cb4 Scan3 : Cr1 , Cr2 , Cr3 , Cr4

Scan1 : Y1 , Y2 , Cb1 , Cr1, Y3 , Y4 , Cb2 , Cr2, Y5 , Y6 , Cb3 , Cr3 , Y7 , Y8 , Cb4 , Cr4

Scan1 : Y1 , Y3 , Cb1 , Cr1, , Y2 , Y4 , Y5 , Y7 , Cb3 , Cr3 , Y6 , Y8 , Y7 , Y8 , Cb4 , Cr4


Example
Example

FFD8

FFC9 00 11 08 00 80 00 80 03 01 11 00 02 11 00 03 11 00

FFCC 00 06 00 10 10 05

FFDA 00 08 01 01 01 00 00 3F 00 …

FFCC 00 06 01 10 11 05

FFDA 00 08 01 02 11 00 3F 00 …

FFDA 00 08 01 03 11 00 3F 00 …

FFD9


Markers
Markers

Code Name Category

FF01 TEM For temporary use in arithmetic coding

FF02-FFBF RES Reserved

FFC0 SOF0Nondifferential Huffman –coding frames Baseline DCT

FFC1 SOF1Nondifferential Huffman –coding frames Extended sequential DCT

FFC2 SOF2Nondifferential Huffman –coding frames Progressive DCT

FFC3 SOF3Nondifferential Huffman –coding frames Lossless sequential

FFC4 DHT Define Huffman Table(s)

FFC5 SOF5 Differential Huffman –coding frames differential sequential DCT

FFC6 SOF6 Differential Huffman –coding frames differential progressive DCT

FFC7 SOF7 Differential Huffman –coding frames differential lossless

FFC8 JPG Reserved for JPEG extension

FFC9 SOF9Nondifferential arithmetic–coding frames Extended sequential DCT

FFCA SOF10Nondifferential arithmetic–coding frames Progressive DCT

FFCB SOF11Nondifferential arithmetic–coding frames Lossless sequential


Markers cont
Markers Cont..

FFCC DAC Define Arithmatic Coding

FFCD SOF13 Differential arithmetic- coding frames differential sequential

FFCE SOF14 Differential arithmetic- coding frames differential progressive

FFCF SOF15 Differential arithmetic- coding frames differential lossless

FFD0-FFD7 RSTm Restart with modulo 8 counter m

FFD8 SOI Start of image

FFD9 EOI End of Image

FFDA SOS Start of Scan

FFDB DQT Define quantization table

FFDC DNL Define number of lines

FFDD DRI Define restart interval

FFDE DHP Define Hierarchical progression

FFDF EXP Expand reference images

FFE0-FFEF APPn Reserved for application use (two different applications may have conflicting usage of APPn)

FFF0-FFFD JPGn Reserved for JPEG extension

FFFE COM Comment


Frames and scans
Frames and Scans

Frame Header SOFn

Parameter Symbol Size

Marker ( FFC0-3, 5-7, 9-B,D-F) SOFn 16

Frame header length Lf 16

Sample precision P 8

Number of lines Y 16

Number of samples per line X 16

Number of components in frame Nf 8

Frame component specification

Component identifier Ci 8

Horizontal sampling factor Hi 4

Vertical sampling factor Vi 4

Quantization table destination selector Tqi 8

The above example shows a three component system. YCrCbwith identical sampling for all components in the vertical direction and twice as many Y samples as Cr or Cb samples in the horizontal direction. Let the first component use quantization table 0 and the rest use quantization table 1. If Y, Cr and Cb are numbered 0, 1, and 2 respectively, the components specification is as given above.


Other header structures
Other Header Structures

Scan Header

DHT Marker Segment

DAC Marker Segment

DQT Marker Segment

Restart Segment


References
References

  • JPEG still image data compression standard,

  • William B Pennebaker, JL Mitchell,

  • VNR , International Thomson Publishing Inc.


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