Offset Length Contents
0 3 bytes "GIF"
3 3 bytes "87a" or "89a"
6 2 bytes <Logical Screen Width>
8 2 bytes <Logical Screen Height>
10 1 byte bit 0: Global Color Table Flag (GCTF)
bit 1..3: Color Resolution
bit 4: Sort Flag to Global Color Table
bit 5..7: Size of Global Color Table: 2^(1+n)
11 1 byte <Background Color Index>
12 1 byte <Pixel Aspect Ratio>
13 ? bytes <Global Color Table(0..255 x 3 bytes) if GCTF is one>
? bytes <Blocks (optional)>
1 bytes <Trailer> (0x3b)
Offset Length Contents
0 1 byte Image Separator (0x2c)
1 2 bytes Image Left Position
3 2 bytes Image Top Position
5 2 bytes Image Width
7 2 bytes Image Height
8 1 byte bit 0: Local Color Table Flag (LCTF)
bit 1: Interlace Flag
bit 2: Sort Flag
bit 2..3: Reserved
bit 4..7: Size of Local Color Table: 2^(1+n)
? bytes Local Color Table(0..255 x 3 bytes) if LCTF is one
1 byte LZW Minimum Code Size
[ // Blocks
1 byte Block Size (s)
(s)bytes Image Data
]*
1 byte Block Terminator(0x00)
Offset Length Contents
0 1 byte Extension Introducer (0x21)
1 1 byte Graphic Control Label (0xf9)
2 1 byte Block Size (0x04)
3 1 byte bit 0..2: Reserved
bit 3..5: Disposal Method
bit 6: User Input Flag
bit 7: Transparent Color Flag
4 2 bytes Delay Time (1/100ths of a second)
6 1 byte Transparent Color Index
7 1 byte Block Terminator(0x00)
Offset Length Contents
0 1 byte Extension Introducer (0x21)
1 1 byte Comment Label (0xfe)
[
1 byte Block Size (s)
(s)bytes Comment Data
]*
1 byte Block Terminator(0x00)
Offset Length Contents
0 1 byte Extension Introducer (0x21)
1 1 byte Plain Text Label (0x01)
2 1 byte Block Size (0x0c)
3 2 bytes Text Grid Left Position
5 2 bytes Text Grid Top Position
7 2 bytes Text Grid Width
9 2 bytes Text Grid Height
10 1 byte Character Cell Width(
11 1 byte Character Cell Height
12 1 byte Text Foreground Color Index(
13 1 byte Text Background Color Index(
[
1 byte Block Size (s)
(s)bytes Plain Text Data
]*
1 byte Block Terminator(0x00)
Offset Length Contents
0 1 byte Extension Introducer (0x21)
1 1 byte Application Label (0xff)
2 1 byte Block Size (0x0b)
3 8 bytes Application Identifire
[
1 byte Block Size (s)
(s)bytes Application Data
]*
1 byte Block Terminator(0x00)
GIF87a: GIF Header Image Block Trailer
GIF89a: GIF Header Graphic Control Extension Image Block Trailer
GIF Animation GIF Header Application Extension [ Graphic Control Extension Image Block ]* Trailer
See also:
| file: /techref/fileext/gif/index.htm, 4KB, , updated: 2007/7/27 14:10, local time: 2009/11/7 16:07,
38.107.191.111:LOG IN
|
| ©2009 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? Please DO link to this page! Digg it! <A HREF="http://piclist.com/techref/fileext/gif/index.htm"> GIF: Graphics Interchange Format</A> |
| Did you find what you needed? |
|
|
|
.