Wavelet-Based Image Compression - Introduction to Data Compression - page 557

Parameter Size (bytes) Description

PLT 2 Marker (0xFF58)

Lplt 2 Length of segment in bytes

Zplt 1 Index relative to other PLT marker segments in the header

Iplt i variable Length of i th packet

...

SOC
0xFF4F

SOT Tile 1

markers

SOD Tile

Part 1

SOT Tile

Part n

EOC
OxFFD9

Main

0xFF90

0xFF93 0xFF90

SOC SIZ COD COC QCD QCC RGN

0xFF5E

POD
0xFF5F

TLM
0xFF60 0xFF55

PPM PLM

0xFF57

CME

0xFF4F 0xFF51 0xFF52 0xFF53 0xFF5C 0xFF5E 0xFF64

F I GU R E 16 . 24 Organization of markers in the main header. Optional markers

are shown in dashed boxes [ 219 ].

The packet headers can be organized in one of three ways. In the first approach, all the
packet headers can be placed together using a PPM marker so that multiple reads are not
required to decode the different headers. This organization can occur only in the main header
and is as follows:

Parameter Size (bytes) Description

PPM 2 Marker (0xFF60)

Lppm 2 Length of segment in bytes

Zppm 1 Index relative to other PPM

marker segments in the header

Nppm i 4 Number of bytes of Ippm infor-

mation for i th tile-part.
One value for each tile-part.

Ippm i , j variable Packet header for every packet in

order in the tile-part. The com-
ponent number, layer, and resolu-
tion are determined from method
of progression or POD. One value
for each packet in the tile-part.

The second approach is to place packed packet headers in the tile-part header using the marker
PPT. The structure of the segment is the same as that of the PPM except only the headers of
the packets in the tile-part are included.