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April 2004

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2004.04.15 00:26 "Large TIFF files", by Lynn Quam
2004.04.15 01:57 "Re: Large TIFF files", by Frank Warmerdam
2004.04.15 02:17 "Re: Large TIFF files", by Lynn Quam
2004.04.15 04:41 "Re: Large TIFF files", by Chris Cox
2004.04.15 06:05 "Re: Large TIFF files", by Rob Tillaart
2004.04.15 12:23 "Re: Large TIFF files", by Dan Smith
2004.04.15 13:33 "Re: Large TIFF files", by Frank Warmerdam
2004.04.15 21:51 "Re: Large TIFF files", by Chris Cox
2004.04.16 17:23 "Re: Large TIFF files", by Joris Van Damme
2004.04.17 02:50 "Re: Large TIFF files", by Joris Van Damme
2004.04.20 08:29 "Re: Large TIFF files", by Rob Tillaart
2004.04.20 14:20 "Re: Large TIFF files", by Joris Van Damme
2004.04.21 07:06 "Re: Large TIFF files", by Rob Tillaart
2004.04.20 20:44 "Re: Large TIFF files", by Chris Cox
2004.04.21 07:30 "Re: Large TIFF files", by Rob Tillaart
2004.04.21 17:54 "Re: Large TIFF files", by Chris Cox
2004.04.22 07:38 "Re: Large TIFF files", by Rob Tillaart
2004.04.22 18:21 "Re: Large TIFF files", by Chris Cox
2004.04.22 18:34 "Re: Large TIFF files", by Thomas J Kacvinsky
2004.04.22 18:43 "Re: Large TIFF files", by Chris Cox
2004.04.22 18:49 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 19:52 "Re: Large TIFF files", by Phillip Crews
2004.04.22 20:45 "Re: Large TIFF files", by Andrey Kiselev
2004.04.22 21:06 "Re: Large TIFF files", by Chris Cox
2004.04.22 21:35 "Re: Large TIFF files", by Joris Van Damme
2004.04.22 21:49 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 21:59 "Re: Large TIFF files", by Chris Cox
2004.04.22 22:23 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 22:31 "Re: Large TIFF files", by Joris Van Damme
2004.04.22 22:34 "Re: Large TIFF files", by Chris Cox
2004.04.22 23:03 "Re: Large TIFF files", by Joris Van Damme
2004.04.22 23:17 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 23:59 "Re: Large TIFF files", by Chris Cox
2004.04.23 15:58 "Re: Large TIFF files", by Leonard Rosenthol
2004.04.26 14:50 "Re: Large TIFF files", by Marco Schmidt
2004.04.23 12:45 "Re: Large TIFF files", by John Aldridge
2004.04.23 13:12 "Re: Large TIFF files", by Joris Van Damme
2004.04.23 20:37 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.23 22:31 "Re: Large TIFF files", by Chris Cox
2004.04.23 22:38 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.23 22:58 "Re: Large TIFF files", by Chris Cox
2004.04.26 10:03 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 14:32 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.26 07:30 "Re: Large TIFF files", by Rob Tillaart
2004.04.26 09:58 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 11:06 "Re: Large TIFF files", by Rob Tillaart
2004.04.26 11:28 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 12:05 "Re: Large TIFF files", by John Aldridge
2004.04.26 12:33 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 12:53 "Re: Large TIFF files: explicitly different format", by Dan Smith
2004.04.26 13:16 "Re: Large TIFF files: explicitly different format", by Joris Van Damme
2004.04.26 17:10 "Re: Large TIFF files: explicitly different format", by Chris Cox
2004.04.26 11:38 "Re: Large TIFF files", by Gerben Vos
2004.04.26 12:50 "Re: Large TIFF files", by Joris Van Damme
2004.04.27 06:12 "Re: Large TIFF files", by Rob Tillaart
2004.04.26 16:54 "Re: Large TIFF files", by Chris Cox
2004.04.23 13:16 "Re: Large TIFF files", by Phillip Crews
2004.04.23 20:28 "Re: Large TIFF files", by Andrey Kiselev
2004.04.23 15:54 "Re: Large TIFF files", by Leonard Rosenthol
2004.04.22 10:32 "Re: Large TIFF files", by Gerben Vos
2004.04.22 18:41 "Re: Large TIFF files", by Chris Cox
2004.04.22 19:45 "Re: Large TIFF files", by Dan Smith
2004.04.22 20:08 "Re: Large TIFF files", by Chris Cox

2004.04.20 08:29 "Re: Large TIFF files", by Rob Tillaart

[the discussion continues]

Hi,

The discussions of the 64 bit TIFF bring up some good insights
(requirements?)

There are in essence only 2 routes for 64 bit tiff
- compatibility with existing
- breaking with existing (but keeping as many good things as possible)

The first leads to all kinds of trouble as mentioned in earlier mails.
Frank proposed a new 64 bit format BTIFF (or BIF: Big Image File or BIg
File) and 
for now this seems to me the most promissing way. BIF could inherit the 
tag structure of TIFF with some 'minor' changes.

Who are the stakeholders for 64 bit.
1) applications that make huge images or (eg www.jumboscan.com)
2) applications that make huge multipage images (eg highres video
camera)
3) applications that do both.

It seems to me that many applications will not need 64 bit. 


PRELIM. PROPOSAL BIF
-----------------------
All types will be mapped upon signed 64 bit, 
alignment to 64 bit or 8 bytes

TYPES
-----
1 	= ASCII		string 0 terminated 
2	= BLOB		bytearray		
3 	= DOUBLE
4	= LONG64	
5	= RATIONAL64	LONG64/LONG64	(16 bytes)
6 	= COMPLEX	LONG64-LONG64	(16 bytes)

All nummeric types are signed, this would make files max. 2^63 bytes in
stead of 2^64
seems large enough for now. 2^63 = 9.223.372.036.854.775.808
All (tiff32) types are mapped upon long64 (even boolean)
This seems a waste of bytes but if we talk about files >> 4GB these few
bytes 
won't matter too much I assume.


HEADER
---------
Bytes 0-1: endianess 		// must we keep this ?
Bytes 2-7: SAM 64		// in ASCII 
Bytes 8-15: 64 bit IFD offset	// 0000000 for last IFD


The number of directory entries is also a LONG64;


TAGS
-----
Byte 0-7: 	tag
Byte 8-15:	type
Byte 16-23:	value 		(type=3-6)	length 		(type=1,2)
Byte 24-31:	opt. value 	(type=5,6)	64bit offset 	(type=1,2)


Tag's are the same as in the TIFF 6.0 spec. preceded with 0's.
The range with the first 32 bit a 0 are reserved for this
'compatibility'
The range with the first 32 bit a 1 are reserved for 'the commitee'
(whoever ...)


METATAG
----------
There is one new TAG the metaTAG
	FFFFFFFF-00000001	// Metatag
	00000000-00000001	// ASCII
	some length
	offset --> data

	data = "XXXXXXXX-XXXXXXXX:description"
	X = value of a new tag used in this file

	example data: "11111111-00000001: A tag for internal use of application
X only."

this way applications can extend the metadata in a documented way. Note
that the tag is not registered in any way and only valid for this file. 

END PRELIM PROPOSAL

I didn't think about the image data yet but for now compressions are
just same, 
tiles and stripes are just as usual only they have a 64 bit
offset/count. I think 
it is good practice to keep tiles small. 
	
So far my thinking about the large tiff files for now,

Please shoot: comments, remarks, questions, ideas, improvements,
alternatives, ... 

best regards,
rob tillaart

[and the discussion continues ...]