JPEG Joint

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JPEG Joint Photographic Expert Group
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(No Transcript)
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Multiple components, interleaving and minimum
coded unit
A1
A2
B1
B2
C1
C2
An
Bn
Cn
non-interleaved MCU 1 data unit 8x8 pixels
A1
A2
An
B1
B2
Bn
C1
C2
Cn
scan1
scan2
scan3
MCU
interleaved MCU3 data units
A1
A2
An
B1
B2
Bn
C1
C2
Cn
scan1
4
Multiple components with different dimensions
A1
A2
B1
B2
C1
C2
An
Bn/2
Cn/2
MCU
interleaved MCU4 data units
A2
A3
An-1
B1
B2
Bn/2
C1
C2
Cn/2
A1
A4
An
scan1
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X number of horizontal samples in image Y
number of vertical samples in image xi number
of horizontal samples in component Ci yi number
of vertical samples in component Ci
C4
xi ceil(XHi/Hmax) yi ceil(YVi/Vmax)
C3
C2
C1
Example XY512 Hmax4 Vmax2 C1 H14 V11
x1512 y1256 C2 H22 V22 x2256 y2512 C3 H31
V31 x3128 y3256
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SOI APP lt ...gt DQT ltquantisation table 1gt DQT
ltquantisation table 2gt SOF ltimage info, size
gt DHT lthuffmann table 1gt DHT lthuffmann table
2gt DHT lthuffmann table 3gt DHT lthuffmann table
4gt SOS ltencoded datagt
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SOI Frame EOI
Quant. Tables Frame header Scan1 Scan2
Scann
SOF
DQT
Huffmann tables Scan header ECS
DHT
SOS
MCU1 MCU2 ... MCUn
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Frame header structure
Parameter size in bits Marker
(FFC0FFCF) 16 frame header length 16 sample
precision 8 number of lines 16 number of
samples/line 16 number of components in
frame 8 for each frame component component
identifier 8 horizontal sampling
factor 4 vertical sampling factor 4 quantizatio
n table destination selector 8
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Scan header structure
Parameter size in bits Marker
(FFDA) 16 scan header length 16 number of
components in scan 8 for each
component component selector 8 DC entropy
coding table selector 4 AC entropy coding table
selector 4 start of spectral selection or
predictor selection 8 end of spectral
selection 8 successive approximation bit
stream position high 4 successive approximation
bit stream position low 4
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DHT marker segment structure
Parameter size in bits Marker
(FFC4) 16 Huffman table definition
length 16 for each Huffman table table
class 4 Huffman table identifier
4 number of Huffman codes of length i
(Li) for i 1..16 8 value associated with
each Huffman code for i 1..16 j 1..Li 8
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Table for luminance DC difference (p. 509)
0 00 1 010 2 011 3 100 4 101 5 110 6 1110 7 11110
8 111110 9 1111110 10 11111110 11 111111110
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FF C4 0 1F 0 0 1 5 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1
2 3 4 5 6 7 8 9 A B
5 words of length 3
Length 31 B
values
1 words of length 2
Class ACDC
0 words of length 1
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DQT marker segment structure
Parameter size in bits Marker
(FFDE) 16 Quantization table definition
length 16 for each Quantization table
Quantization table element precision 4 Quantizat
ion table identifier 4 Quantization table
element (0..63) 8 or 16
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Structure of the Guerrier code
jpeg.c jpeg.h utils.c parse.c get_bits (
) get_next_MK ( ) load_quant_tables (
) init_MCU ( ) process_MCU (
) fast_idct.c idct_1d ( ) IDCT (
) color.c tree_vld.c load_huff_tables (
) get_symbol ( ) huffman.c unpack _block (
) spy.c unpack.c